On the Syntheses and Reactions of Boroles and Boraindenes

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2014-10-08 On the Syntheses and Reactions of Boroles and Boraindenes

Houghton, Adrian Yuri

Houghton, A. Y. (2014). On the Syntheses and Reactions of Boroles and Boraindenes (Unpublished doctoral thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/27197 http://hdl.handle.net/11023/1925 doctoral thesis

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On the Syntheses and Reactions of Boroles and Boraindenes

Adrian Yuri Houghton

A THESIS

SUBMITTED TO THE FACULTY OF GRADUATE STUDIES

IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE

DEGREE OF DOCTOR OF PHILOSOPHY

Department of Chemistry

CALGARY, ALBERTA

September, 2014

Abstract

Highly Lewis-acidic boranes are an important class of compounds in both fundamental and applied chemistry. Recently, a sub-class of boranes known as boroles – five-membered unsaturated boracycles – has begun to receive attention due to the interesting properties afforded by the anti-aromatic nature of these compounds.

We synthesized and characterized a new class of boroles wherein the borole ring is fused to a benzene ring. These “boraindenes” were found to be highly Lewis acidic by the Gutmann-

Beckett method, even more so than the ubiquitous tris-pentafluorophenylborane. Structural and computational evidence supports the notion that these compounds are anti-aromatic, which likely contributes to their Lewis acidity. A series of six derivatives was synthesized, and it was found that they had only marginally different absorption spectra.

Previous work in our group showed that perproteo and perfluoro-pentaphenylboroles are capable of irreversibly activating dihydrogen. The mechanism of this reaction was investigated both experimentally and computationally, and it was found that the reaction was bimolecular in nature. Furthermore, the reaction involves the formation of a transient dihydrogen-borole adduct which quickly adds dihydrogen across the boron-carbon bond. A 1,2-hydride shift can lead to a cisoid product, and cleavage of the boron-carbon bond results in a ring-opened intermediate that ultimately rearranges to give the transoid product; independent synthesis of this ring-opened intermediate confirms that it does indeed give the transoid product.

The most Lewis acidic of the boraindenes, perfluoro-1,2,3-triphenyl-1-boraindene, appears to react reversibly with dihydrogen gas. This compound has proven capable of

ii mediating the hydrogenation of cyclohexene, though its precise role remains obscured in part due to the fact that it reacts with cyclohexene itself.

Perfluoro-1,2,3-triphenyl-1-boraindene was found to reversibly form an adduct with triethylsilane in solution, an adduct that was also isolated in the solid state. The solution-phase equilibrium was characterized by a titration followed by nuclear magnetic resonance spectroscopy, which revealed that the equilibrium is nearly thermoneutral at room temperature but favours adduct formation at lower temperatures. Infrared spectroscopy and X-ray diffraction analysis on solid samples confirm that the adduct is formed via a three-centre, two-electron silicon-hydrogen-boron bonding interaction. Perfluoro-1,2,3-triphenyl-1-boraindene was also found to be an active catalyst for the hydrosilation of olefins.

iii Acknowledgements

This doctoral thesis represents the culmination of five years of hard work, and I would be remiss were I not to acknowledge all those who aided me throughout this endeavour. First and foremost

I would like to thank my supervisor Professor Warren Edward Piers, without whom none of this would have been possible. His keen insights and intense dedication are aspects I have tried to incorporate into myself, and working in his group has moulded me into the scientist that I am today.

I would like to thank the members of my supervisory committee, Dr. Todd Sutherland and Dr. Thomas Baumgartner, for their additional support throughout my degree. I would also like to thank the other members of my examination committee, Dr. Peter Tieleman and Dr. T.

Don Tilley, for taking the time to evaluate my thesis. Gratitude is extended to Dr. Roland

Roesler and Dr. David Schriemer for serving on my candidacy committee.

All the members of the Piers group, past and present, have helped me in some way or another, whether it be through showing me a new technique, discussing experiments or teaching me something new. I would like to thank Master Juan Felipe Araneda in particular, who has been a fellow boron chemist from the beginning, for his help, friendship, and aid in maintaining the air- and moisture- free working paradise that is the Boron Box. In addition to his help in the lab, Dr. Francis A. Leblanc introduced me to Crossfit and helped me get into some of the best shape in my life. I would also like to thank Dr. Tracy Griffin (Lohr), Dr. Rich Burford, Master

Terry Chu, Dr. Lauren Mercier, Dr. Adam Marwitz, Dr. Andrey Khaliman, Dr. Dmitry

Gutsulyak, Dr. Erin Leitao, Dr. Thomas Wood, Dr. Matt Sloan, Dr. Andreas Berkefeldt, Dr.

Benedikt Neue and Dr. Cheng Fan.

iv There are a number of people to whom I owe thanks for the development of my abilities as a crystallographer (if I can presume to call myself one). Dr. Masood Parvez taught me the principles of crystallography and showed me how to use the instruments, and I have received additional support from Doctors Javier Borau-Garcia, Jason Dutton, Michael Sgro, and Denis

Spasyuk.

The instrumentation staff at the University of Calgary provide and maintain the excellent facilities that make much of our work possible. Dr. Michelle Forgeron has done an excellent job of leading her team while also providing support to our lab during the move. Qiao Wu, Wade

White, Dorothy Fox and Jian Jun Li have also been incredibly helpful and pleasant to work with.

Additional support from around the department has been exemplary. Mark Toonen is a truly gifted and hard-working glassblower without whom I would likely be graduating much later. The machine shops and electrical shops have been instrumental in keeping our lab functioning, and I would like to thank them all for their efforts. Bonnie King and Janice

Crawford have been a great help keeping me on track and aiding in scholarship applications, for which I am very grateful.

My parents, Dean and Anne Houghton, have been unwaveringly loving and supportive throughout my entire life. My little sister Vanessa has been an excellent friend and confidante, of whom I am very proud. I am happy to have had them so close throughout this degree, for they have surely made it easier.

My friends, both within and outside the department, have each certainly made things more fun and enjoyable than if they had been absent during this time in my life. Dustin Pearson kept me going to the gym in the mornings for two years and I am stronger because of it. I would

v like especially to thank Ryan Bebb, Leah Kilvert and Mari Boesen. I would also like to offer a heartfelt thanks to the Burner community as a whole, for showing me just how rad life can be.

vi Table of Contents

Abstract...... ii Acknowledgements...... iv Table of Contents...... vii List of Tables ...... x List of Figures...... xiv List of Schemes...... xviii List of Symbols, Abbreviations and Nomenclature...... xxi List of Numbered Compounds in Chapters 1 and 2...... xxvi List of Numbered Compounds in Chapters 3 and 4...... xxvii List of Numbered Compounds in Chapter 5...... xxviii List of Numbered Intermediates ...... xxviii

CHAPTER ONE: INTRODUCTION...... 1 1.1 Lewis Acids and Bases ...... 1 1.2 Lewis Acidity Scales ...... 5 1.3 Applications of Boron Lewis Acids...... 8 1.4 Boroles ...... 14 1.4.1 Aromaticity and Anti-aromaticity ...... 15 1.4.2 Borole Lewis Acids ...... 18 1.5 Scope of the Thesis ...... 22

CHAPTER TWO: SYNTHESIS AND PROPERTIES OF PENTAARYLBOROLES AND 1- BORAINDENES...... 23 2.1 Introduction: Synthesis of Pentaphenylborole and Perfluoropentaphenylborole ... 23 2.2 Synthesis and Characterization of 1-boraindenes...... 25 2.2.1 Synthesis of 1,2,3-triphenyl-1-boraindene ...... 27 2.2.2 Synthesis of perfluoro-1,2,3-triphenyl-1-boraindene ...... 29 2.3 Assessing the antiaromaticity of 1-1, 1-2, 1-3 and 1-4...... 38 2.4 Assessment of Lewis acidity...... 40 2.5 Synthesis of Boraindene Derivatives...... 42 2.6 Electronic Properties of Boraindenes ...... 49 2.7 Conclusions...... 54

CHAPTER THREE: THE ACTIVATION OF DIHYDROGEN BY BOROLES AND BORAINDENES...... 55 3.1 Introduction: Activation of Dihydrogen by Pentaarylboroles ...... 55 3.2 Proposed Mechanism...... 59 3.3 Experimental Elucidation of the Mechanism of H2 Activation by Boroles...... 60 3.3.1 Rational Synthesis of the Ring-opened Intermediate ...... 65 3.4 DFT Studies ...... 69 3.5 Activation of Dihydrogen by Boraindenes ...... 73 3.6 The Boraindene-Mediated Hydrogenation of Cyclohexene ...... 78 3.6.1 The reaction of 1-4 and cyclohexene...... 80 3.6.2 Summary of the thermal decomposition of 3-5...... 82 3.6.3 Catalytic Hydrogenation Experiments ...... 84

vii 3.7 DFT Studies on the Activation of Hydrogen and Hydrogenation of Olefins by 1-485 3.8 Conclusions...... 87

CHAPTER FOUR: THE ACTIVATION OF TRIETHYLSILANE BY PERFLUORO-1,2,3- TRIPHENYL-1-BORAINDENE...... 89 4.1 Introduction...... 89 4.2 Solution-phase behaviour of the Silane-Boraindene equilibrium...... 93 4.2.1 Thermodynamics of the Boraindene-Silane equilibrium ...... 94 4.2.2 Structural Characterization of the Boraindene-Silane Adduct 4-1...... 100 4.3 Reactions of the Silane-Boraindene Adduct...... 104 4.3.1 Reactions of the Boraindene-Silane Adduct with the Chloride Ion ...... 104 4.3.2 Boraindene-catalyzed Hydrosilations of Olefins...... 107 4.4 Conclusions...... 109

CHAPTER FIVE: CONCLUSIONS AND FUTURE WORK ...... 110 5.1 Conclusions...... 110 5.2 Future Work...... 111 5.2.1 Boraindene Derivatives ...... 111 5.2.2 A New Direction for Anti-Aromatic Boron Chemistry: “B-N Boraindenes”113

CHAPTER SIX: EXPERIMENTAL DETAILS ...... 118 6.1 General Considerations...... 118 6.2 Instrumentation ...... 118 6.2.1 NMR Data Reporting ...... 119 6.2.2 Quantum Chemical Calculations...... 119 6.3 Experimental Details for Chapter 2 ...... 120 6.3.1 Synthesis of Boraindene 1-3 & Derivatives ...... 120 6.3.1.1 Synthesis of Cp2ZrPh2 ...... 120 6.3.1.2 Synthesis of Zirconaindenes ...... 121 6.3.1.3 Synthesis of Stannaindenes...... 124 6.3.1.4 Synthesis of Boraindenes...... 128 6.3.2 Synthesis of Boraindene 1-4...... 132 6.3.2.1 Synthesis of Cp2Zr(o-C6HF4)2...... 132 6.3.2.2 Synthesis of 1,1-bis(cyclopentadienyl)-2,3-bis(pentafluorophenyl)-4,5,6,7- tetrafluoro-1-zirconaindene 2-10...... 133 6.3.2.3 Synthesis of 1,1-dimethyl-2,3-bis(pentafluorophenyl)-4,5,6,7-tetrafluoro-1- stannaindene 2-8 ...... 134 6.3.2.4 Synthesis of 1-bromo-2,3-bis(pentafluorophenyl)-4,5,6,7-tetrafluoro-1- boraindene 2-11...... 135 6.3.2.5 Synthesis of 1,2,3-tris(pentafluorophenyl)-4,5,6,7-tetrafluoro-1-boraindene 1-4 ...... 136 6.3.3 Gutmann-Beckett Experiments ...... 137 6.4 Experimental Details for Chapter 3 ...... 138 6.4.1 Synthesis...... 138 6.4.1.1 Synthesis of 3-3 ...... 138 6.4.1.2 Synthesis of 3-4 ...... 139 6.4.1.3 Synthesis of 3-5 ...... 140

viii 6.4.1.4 Synthesis of 3-6 ...... 141 6.4.2 Kinetics experiments for the Activation of Dihydrogen by Boroles...... 142 6.4.2.1 Kinetic Isotope Effects...... 142 6.4.3 NMR Tube Experiments...... 143 6.4.3.1 Reaction of 3-3 with DiBAl-H...... 143 6.4.3.2 Reaction of 1-4 with H2 ...... 143 6.4.3.3 Reaction of 3-4 with Me2Si(H)Cl ...... 144 6.4.3.4 Thermal Decomposition of 3-5...... 144 6.4.3.5 Thermal Decomposition of 3-5 under Deuterium...... 144 6.4.4 Hydrogenation Experiments...... 144 6.4.4.1 Hydrogenation of cyclohexene (20% loading) ...... 144 6.4.4.2 Hydrogenation of cyclohexene (10% loading)...... 145 6.5 Experimental Details for Chapter 4 ...... 145 6.5.1 Thermodynamics Experiments...... 145 6.5.1.1 Room Temperature NMR Titrations...... 145 6.5.1.2 Variable Temperature NMR Titrations...... 146 6.5.2 Equilibrium Isotope Effect Measurements...... 147 6.5.3 Variable Temperature 1H NMR measurements...... 148 6.5.4 Synthesis...... 148 6.5.4.1 Synthesis of (Et3Si)2O...... 148 6.5.4.2 Synthesis of 4-2 ...... 148 6.5.4.3 Synthesis of 4-3 ...... 149 6.5.5 Other NMR tube Experiments...... 150 6.5.5.1 Stoichiometric reaction of 1-4 with Et3SiH and PPNCl...... 150 6.5.6 Hydrosilation Experments ...... 150 6.5.6.1 1-triethylsilyl-3,3-dimethylbutane (4-4) ...... 151 6.5.6.2 1-triethylsilyl-2,2-diphenylethane (4-5)...... 151 6.5.6.3 Cyclohexyltriethylsilane (4-6) ...... 151 References...... 152

APPENDIX A: CRYSTALLOGRAPHIC DATA TABLES, ATOMIC COORDINATES AND METRICAL DATA ...... 165

APPENDIX B: CALCULATED GEOMETRIES...... 217

ix List of Tables

Table 1: Comparative bond lengths (Å) of the calculated structures of 1-3 and 1-4, and of the X-ray structure of 1-4...... 39

Table 2: Gutmann-Beckett Lewis Acid Strengths and NICS(1)zz of 1-1, 1-2, 1-3, and 1-4...... 41

Table 3. Onsets of absorption, HOMO-LUMO gap energies, λmax and of boraindene derivatives ...... 51

Table 4: Total chemical shifts (Δδtot) and equilibrium constants (Ka) from the NMR titration of boraindene 1-4 with Et3SiH...... 98

19 Table 5: Data for the F NMR titration of 1-4 with Et3SiH at 300K...... 146

19 Table 6: Data for the F NMR titration of 1-4 with Et3SiH at lower temperatures ...... 147

Table 7: Data for the determination of the Ka-D for 1-4 and Et3SiD ...... 147

Table A1. Crystal data and structure refinement for Cp2Zr(o-C6HF4)2...... 165

Table A3. Bond lengths [Å] and angles [°] for Cp2Zr(o-C6HF4)2...... 166

Table A4: Crystal data and structure refinement for 1-3C6F5...... 168

Table A5: Atomic coordinates (x 104) and equivalent isotropic displacements parameters (Å2 3 x 10 ) for 1-3C6F5. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 169

Table A6: Bond lengths (Å) and angles (˚)for 1-3C6F...... 169

Table A7. Crystal data and structure refinement for 1-4...... 171

Table A8. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 1-4. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 171

Table A9. Bond lengths [Å] and angles [°] for 1-4...... 172

Table A10. Crystal data and structure refinement for 2-7CH3...... 173

x Table A11. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters

(Å2x 103) for 2-7CH3. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 174

Table A12. Bond lengths [Å] and angles [°] for 2-7CH3...... 175

Table A13. Crystal data and structure refinement for 2-7CF3...... 176

Table A14. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters

(Å2x 103) for 2-7CF3. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 177

Table A15. Bond lengths [Å] and angles [°] for 2-7CF3...... 177

Table A16. Crystal data and structure refinement for 2-7F...... 179

Table A17. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 2-7F. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 179

Table A18. Bond lengths [Å] and angles [°] for 2-7F...... 180

Table A19. Crystal data and structure refinement for 2-7C6F5...... 181

Table A20. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters

(Å2x 103) for 2-7C6F5. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 182

Table A21. Bond lengths [Å] and angles [°] for 2-7C6F5...... 183

Table A22. Crystal data and structure refinement for 2-8...... 186

Table A23. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 2-8. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 186

Table A24. Bond lengths [Å] and angles [°] for 2-8...... 187

Table A25. Crystal data and structure refinement for 2-9CH3...... 188

Table A26. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103)for 2-9CH3. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 189

Table A27. Bond lengths [Å] and angles [°] for 2-9CH3...... 190

xi Table A28. Crystal data and structure refinement for 2-9C6F5...... 192

Table A29. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters

(Å2x 103) for 2-9C6F5. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 193

Table A30. Bond lengths [Å] and angles [°] for 2-9C6F5...... 194

Table A31. Crystal data and structure refinement for 2-10...... 196

Table A32. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 2-10. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 197

Table A33. Bond lengths [Å] and angles [˚] for 2-10...... 198

Table A34. Crystal data and structure refinement for 2-11...... 200

Table A35. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 2-11. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 201

Table A36. Bond lengths [Å] and angles [°] for 2-11...... 201

Table A37. Crystal data and structure refinement for 3-3...... 203

Table A38. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 3-3. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 203

Table A39. Bond lengths [Å] and angles [°] for 3-3...... 204

Table A40. Crystal data and structure refinement for 3-4...... 206

Table A41. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 3-4. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 207

Table A42. Bond lengths [Å] and angles [°] for 3-4...... 208

Table A43: Crystal data and structure refinement for 3-6 ...... 209

Table A44: Atomic coordinates (x 104) and equivalent isotropic displacements parameters 2 3 (Å x 10 ) for 3-6. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 210

xii Table A45: Bond lengths (Å) and angles (˚) for 3-6...... 211

Table A46: Crystal data and structure refinement for 4-1 ...... 213

Table A47: Atomic coordinates (x 104) and equivalent isotropic displacements parameters 2 3 (Å x 10 ) for 4-1. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor...... 213

Table A48: Bond lengths (Å) and angles (˚) for 4-1...... 214

Table A49: Atomic coordinates (Å) for 1-1 ...... 217

Table A50: Atomic coordinates (Å) for 1-2 ...... 218

Table A51: Atomic coordinates (Å) for 1-3 ...... 219

Table A52: Atomic coordinates (Å) for 1-4 ...... 220

xiii List of Figures

Figure 1. Molecular orbital (MO) depiction of Lewis acid-base adduct bond formation...... 3

Figure 2: Comparison of the hardness, electronegativity and orbital overlap of the trihaloboranes...... 4

Figure 3: Magnetic shielding lines for benzene and borole. Shielded regions (diatropic shift) are denoted by blue dots and deshielded regions (paratropic shift) are denoted by red dots...... 18

Figure 4. Thermal ellipsoid (50%) diagram of bis(2,3,4,5-tetrafluorophenyl) zirconocene. Selected bond lengths (Å): Zr1-C11 2.348(5), Zr1-C17 2.336(5); Selected bond angle (˚): C11-Zr1-C17 101.19(17) ...... 31

Figure 5. Depiction of the face-to-face interaction between two phenyl rings on different molecules of Cp2Zr(o-C6HF4)2...... 31

Figure 6. Thermal ellipsoid (50%) diagram of 2-10. Selected bond lengths (Å): Zr1-C14 2.282(4), C14-C13 1.414(5), C13-C12 1.483(5), C12-C11 1.350(5), Zr1-C11 2.307(4); Selected bond angles (˚)C14-Zr1-C11 75.14(14), C12-C11-Zr1 114.1(3), C11-C12-C13 119.1(3), C14-C13-C12 117.4(3), C13-C14-Zr1 113.1(3); Selected torsion angle (˚): C11-C12-C13-C14 10.10...... 32

Figure 7. Thermal ellipsoid (50%) diagram of stannaindene 2-8. Selected bond lengths (Å): Sn1-C3 2.162(3), C3-C4 1.335(5), C4-C5 1.493(6), C5-C6 1.403(5) Sn1-C6 2.138(4); Selected bond angles (˚): C6-Sn1-C3 81.71(14), C4-C3-Sn1 110.7(3), C3-C4-C5 119.5(3), C4-C5-C6 118.1(3), C5-C6-Sn1 109.8(3); Selected torsion angle (˚): C3-C4- C5-C6 3.27...... 33

Figure 8. Thermal ellipsoid (50%) diagram of boraindene 2-11. Selected bond lengths (Å): B15-C1 1.562(4), C2-C1 1.352(3), C3-C2 1.492(3), C3-C4 1.417(3), B15-C4 1.548(4), Br1-B15 1.878(3); Selected bond angles (˚):C4-B15-C1 105.2(2), C2-C1-B15 107.4(2), C1-C2-C3 111.7(2), C2-C3-C4 109.7(2), C3-C4-B15 106.1(2); Selected torsion angle (˚): C1-C2-C3-C4 1.47...... 34

Figure 9. Thermal ellipsoid (50%) diagram of 1-4. Selected bond lengths (Å): B1–C1 1.575(5), C1–C2 1.353(5), C2–C3 1.483(5), C3–C8 1.415(5), B1–C8 1.553(6); Selected bond angles (º): B1–C1–C2 108.3(3), C1–C2–C3 111.1(3), C2–C3–C8 109.9(3) C3– C8–B1 106.8(3), C8–B1–C1 103.5(3); Selected torsion (º): 5.2...... 35

Figure 10. Depiction of the bond length alternation in the indenyl moiety of 1-4 with measured bond lengths in blue and typical bond lengths in red (Å)...... 36

Figure 11: Depiction of the B-F contacts of 1-4 in the solid state. Selected B-F contact distances (Å) F5-B1 2.873, F9-B1 2.917, F11-B1 2.895, F18-B1 3.482, F19-B1 3.118. ... 37

Figure 12. Optimized structures of 1-4 (left) and 1-3 (right)...... 38

xiv Figure 13. Thermal ellipsoid (50%) diagram of 2-9CH3. Selected bond lengths (Å): Zr1-C4 2.2697, Zr1-C1 2.2729, C1-C2 1.3655, C2-C3 1.4880, C3-C4 1.4183; Selected bond angles (º): C1-Zr1-C4 78.9, Zr1-C1-C2 111.0, C1-C2-C3 120.3, C2-C3-C4 119.8, C3- C4-Zr1 109.7; Selected torsion (º): C1-C2-C3-C4 6.9...... 43

Figure 15. Thermal ellipsoid (50%) diagram of 2-7CH3. Selected bond lengths (Å): Sn1-C1 2.147(5), C2-C1 1.355(8), C3-C2 1.512(7), C3-C4 1.414(8), Sn1-C4 2.134(6); Selected bond angles (˚): C4-Sn1-C1 84.0(2), C2-C1-Sn1 109.6(4), C1-C2-C3 119.0(5), C2-C3- C4 119.5(5), C3-C4-Sn1 107.5(4) ; Selected torsion angle (˚): C1-C2-C3-C4 3.5...... 45

Figure 16. Thermal ellipsoid (50%) diagram of 2-7CF3. Selected bond lengths (Å): Sn1-C2 2.145(7), C2-C7 1.408(10), C7-C8 1.478(10), C8-C9 1.347(10), Sn1-C9 2.152(7); Selected bond angles (˚): C2-Sn1-C9 82.9(3), C7-C2-Sn1 108.1(5), C2-C7-C8 119.3(6), C7-C8-C9 120.1(6), C8-C9-Sn1 109.6(5) ; Selected torsion angle (˚): C1-C2-C3-C4 0. .... 45

Figure 17. Thermal ellipsoid (50%) diagram of 2-7F. Selected bond lengths (Å): Sn1-C1 2.153(5), C2-C1 1.330(7), C3-C2 1.503(7), C3-C4 1.398(7), Sn1-C4 2.135(6); Selected bond angles (˚): C4-Sn1-C1 82.7(2), C2-C1-Sn1 110.1(4), C1-C2-C3119.8(5), C2-C3- C4 118.5(5), C3-C4-Sn1 108.9(4) ; Selected torsion angle (˚): C1-C2-C3-C4 1.65...... 46

Figure 18. Thermal ellipsoid (50%) diagram of 2-7C6F5. Selected bond lengths (Å): Sn1-C3 2.162(5), C3-C4 1.349(6), C4-C5 1.476(7), C5-C6 1.407(7), Sn1-C6 2.130(5); Selected bond angles (˚): C3-Sn1-C6 82.75(19), C4-C3-Sn1 108.5(4), C5-C4-C3 121.4(4), C6- C5-C4 117.8(4), C5-C6-Sn1 109.3(4) ; Selected torsion angle (˚): C1-C2-C3-C4 1.7...... 46

Figure 19. Thermal ellipsoid (50%) diagram of 1-3C6F5. Selected bond lengths (Å): B1–C1 1.585(5), C1–C2 1.349(5), C2–C3 1.491(4), C3–C8 1.416(5), B1–C8 1.561(6); Selected bond angles (º): B1–C1–C2 108.4(3), C1–C2–C3 111.6(3), C2–C3–C8 109.6(3) C3– C8–B1 107.4(3), C8–B1–C1 103.1(3); Selected torsion (º): 0.02...... 47

Figure 20. Depiction of the dimeric, face-to-face stacking of 1-3C6F5 in the solid state...... 48

Figure 21. UV/Vis spectra of boraindenes 1-4, 1-3, 1-3CH3, 1-3F, 1-3CF3 and 1-3C6F5 in CH2Cl2. Inset: expanded region from 400-650 nm...... 50

Figure 22. Calculated (top) and measured (bottom) UV/Vis spectra of 1-3 and Kohn-Sham orbital surfaces of the HOMO and LUMO of 1-3...... 52

Figure 23: Pseudo first-order plots of the repeat trials of the reaction between 1-1 ([1-1]o = 0.016 M) and H2 (ca. 1 atm) in CD2Cl2...... 61

xv Figure 24: Pseudo first-order kinetic plots of the reaction of 1-1 ([1-1]o = 0.016 M) with various pressures of H2 in CD2Cl2. Inset: Isolation method plot for the determination of reaction order in [H2] ...... 62

n Figure 25: Comparative plots of kobs against [H2] for n = 0.5, 1, 1.5 ...... 63

Figure 26: Pseudo first-order plots of the reaction between 1-1 and H2 (red) and D2 (blue) ...... 64

Figure 27: Eyring plot for the reaction of 1-1 with H2 (ca. 1 atm) in CD2Cl2 at 283, 298, 309 and 316 K. Inset: Calculated ∆G‡ at 283, 298, 309 and 316 K...... 65

Figure 28: Thermal ellipsoid diagram (50%) of 3-3. Selected bond lengths (Å) and angles (°): C1−C2 1.361(3), C2−C3 1.486(3), C3−C4 1.354(3), B1−C1 1.571(3), B1−O1 1.367(3), B1−C11 1.568(3); C1−B1−C11 122.05(17), C1−B1−O1 122.99(18), C11−B1−O1 114.76(17), and C1−C2−C3−C4 35.47...... 67

Figure 30: Calculated Gibbs free energies of the activation of H2 by boroles 1-2 (blue) and 1- 1 (pink). Adapted with permission from J. Am. Chem. Soc. 2013 135, 941. Copyright 2013 American Chemical Society...... 69

Figure 31: Computed structures for the H2 adduct I for the fully fluorinated borole 1-2 (top) and the transition state TS1 (bottom) for addition of H2 across the internal B(1)−C(1) bond to form cis-II. Selected bond lengths (Å): (left) H(1)−H(2) 0.814, F(1)−H(1) 2.166, F(2)−H(2) 2.309, C(1)−H(1) 2.056, C(2)−H(2) 2.111, B(1)−H(1) 1.438, B(1)−H(2) 1.443; (right) H(1)−H(2) 1.057,F(1)−H(1) 2.266, F(2)−H(2) 2.391, C(1)−H(1) 1.450, C(2)−H(2) 2.142, B(1)−H(1) 1.328, B(1)−H(2) 1.304. Adapted with permission from J. Am. Chem. Soc. 2013 135, 941. Copyright 2013 American Chemical Society...... 71

19 1 Figure 32. F{ H} spectra of 1-4 in toluene-d8 (top) and of 1-4 after 20 hours under 1 atm H2 at 125˚C...... 74

Figure 33. Thermal ellipsoid (50%) diagram of 3-4. Selected bond lengths (Å) and angles (1): B1–C1 1.575(5), C1–C2 1.353(5), C2–C3 1.483(5), C3–C8 1.415(5), B1–C8 1.553(6); B1–C1–C2 108.3(3), C1–C2–C3 111.1(3), C2–C3–C8 109.9(3), C3–C8–B1 106.8(3), C8–B1–C1 103.5(3)...... 76

1 Figure 34. H NMR spectrum (tol-d8) of the reaction mixture of 3-4 and Me2Si(H)Cl after 24 hrs...... 77

19 1 Figure 35. F{ H} spectra in toluene-d8 of: 3-4 (top), the reaction mixture of 3-4 and Me2Si(H)Cl after 2.5 hrs (second from top), the reaction mixture of 3-4 and Me2Si(H)Cl after 24 hrs (second from bottom) and 1-4 for reference (bottom)...... 77

xvi Figure 36. Thermal ellipsoid (50%) diagram of 3-5...... 79

1 Figure 37: H NMR spectrum (C6D6) of 3-5 after heating at 140 ˚C for 2.5 hours...... 79

Figure 38. Thermal ellipsoid (50%) diagram of 3-6 with fluorine and hydrogen atoms excluded for clarity. Selected bond lengths (Å) , angles (˚) and torsion angles (˚): C1- B1 1.578(3) C14-B1 1.554(3) C28A-B1 1.583(3); C14-B1-C1 115.79(18), C14-B1- C28A 121.14(17), C1-B1-C28A 122.64(18); C7-C1-B1-C14 -43.73...... 81

19 Figure 39. F NMR spectra (C6D6) of 3-5 (top), 3-5 after heating at 140˚C for 2.5 hours (second from top), 1-4 after heating in the presence of excess cyclohexene for 1.5 hours (second from bottom) and 1-4 for reference (bottom)...... 83

Figure 40. Calculated Gibbs free energies (kJ mol-1 ; PBE1PBE/TZVP) for the reaction of 1- 4 with H2 and the subsequent addition of ethylene and elimination of ethane...... 86

19 Figure 41. F NMR spectra of a solution (tol-d8) of 1-4 (0.026 M) with varying [Et3SiH] at 273 K (left) and at varying temperature with a fixed [Et3SiH] = 0.051 M (right)...... 96

19 Figure 42. Scatter plots of the Δδ in the F NMR spectra of 1-4 on titrating with Et3SiH at various temperatures and their fitted curves from the binding isotherm ...... 97

o Figure 43. Van’t Hoff plot for the 1-4/Et3SiH adduct equilibrium with ΔH = -29.7(3) kJ mol-1, ΔSo = 100(1) J mol-1 K-1, and R2 = 0.9995...... 99

1 Figure 44. H NMR spectra of a solution of 1-4 (0.065 M) and Et3SiH (0.052 M) in tol-d8 at variable temperatures (right), overlayed Et3Si-H resonances referenced to the chemical 1 shift of free Et3SiH to highlight decreasing JSiH (centre)...... 101

Figure 45. Infrared spectra (KBr pellet) of Et3SiH (top left), 1-4 (top right), 4-1 (bottom left) and 4-1D (bottom right). Baselines were corrected manually...... 102

Figure 46. Thermal ellipsoid (50%) diagram of 4-1. Selected bond lengths (Å) and angles (˚): Si1-H1 1.51(2), B1-H1 1.46(2), B1-C1 1.616(3), B1-C8 1.608(3), B1-C9 1.605(3); Si1-H1-B1 156.79(19), C1-B1-C9 122.89(16), C1-B1-C8 100.58(15), C8-B1-C9 120.84 (17). Short contacts (Å): F19-C28 3.471(2), F9-C28 3.336(3), F9-C30 3.805(3), F9-C27 3.138(3), F4-C29 3.262(2), F14-C31 3.973(2), Si1-F9 3.391(3), Si1-F4 3.980(3), Si1- F19 4.378(3)...... 103

1 Figure 47. H NMR spectra (toluene-d8) of: Et3SiCl (top) and the stoichiometric reaction mixture of 1-4, Et3SiH, and PPNCl (bottom). *Unreacted Et3SiH...... 106

19 Figure 48. F NMR spectra (toluene-d8) of 4-3 (top), 4-2 (middle), and the stoichiometric reaction of 1-4, Et3SiH, and PPNCl (bottom)...... 107

xvii List of Schemes

Scheme 1. Depiction of a generic three-coordinate borane reacting with a Lewis base...... 2

Scheme 2. Adduct formation between crotonaldehyde and a Lewis Acid ...... 6

Scheme 3. Comparison of the CA and AN trends for (F5C6O)nB(C6F5)3-n where n = 0, 1, 2, 3.... 7

Scheme 4. General reaction scheme for 1,1-carboboration of alkynes...... 9

Scheme 5. Formation of boron allylation reagents from propargyl esters and their diastereoselective reactions with aldehydes...... 10

Scheme 6. Cyclizations of propargyl amides and esters promoted by B(C6F5)3...... 11

Scheme 7. Conversion of trans-4-octene to 1-octene using HB(C6F5)2 ...... 12

Scheme 8. Activation of CO and NO by an intramolecular FLP...... 13

Scheme 9. Activation of Si-H and H-H bonds by HB(C6F5)2...... 13

Scheme 10. Proposed catalytic cycle for the hydrogenation of olefins by HB(C6F5)2 ...... 14

Scheme 11. 5-, 6-, and 7-membered unsaturated boracycles...... 15

Scheme 12. Examples of monocyclic aromatic and antiaromatic compounds...... 16

Scheme 13. Borole-containing compounds featured in this thesis...... 18

Scheme 14. Competition reaction between 1-1, 1-1mes and 4-methylpyridine.92 ...... 20

Scheme 15. Examples of arene- and heteroarene-fused boroles93-97 ...... 20

Scheme 16. Formation of 1-2CO from 1-2 and CO.98 ...... 21

Scheme 17. Synthesis of 1-1...... 23

Scheme 18. Synthesis of 1-2...... 24

Scheme 19. Retrosynthesis of boraindenes 1-3 and 1-4...... 25

Scheme 20. Previously reported stannaindenes ...... 26

Scheme 21. Mechanism of the formation of zirconaindene 2-9 from Cp2ZrPh2 and PhCCPh ... 27

Scheme 22. Synthesis of 1-3...... 28

Scheme 23. Synthesis of 1-4...... 30

xviii Scheme 24. Retrosynthesis of boraindene derivatives...... 42

Scheme 25. Synthesis of boraindene derivatives...... 43

Scheme 26. Modes of activation of dihydrogen by metals...... 55

Scheme 27. FLP-type activation of dihydrogen by B(C6F5)3 and P(t-Bu)3 ...... 57

Scheme 28. Activation of dihydrogen by boroles 1-1 and 1-2...... 58

Scheme 30. Rational synthesis of intermediate trans-III from 3-3...... 66

Scheme 31. Cleavage of the external B-C bond by dihydrogen ...... 73

Scheme 32. Reactions of borole 1-2, borafluorene 1-6 and boraindene with 1-4...... 74

Scheme 33. In situ generation of intermediate IV from chloroborane 3-4 and Me2Si(H)Cl...... 75

Scheme 34. Potential catalytic cycle for the hydrogenation of cyclohexene by boraindene 1-4.. 78

Scheme 35. Reaction of 1-4 with diphenylacetylene...... 80

Scheme 36. Reaction of cyclohexene with 1-4 to form 3-6...... 81

Scheme 37. Proposed mechanism for the formation of 3-6 from 1-4 and cyclohexene...... 82

Scheme 38. Alternate mechanisms for the 1-4-mediated hydrogenation of cyclohexene...... 84

Scheme 39. General hydrosilation of unsaturated organic compounds...... 89

Scheme 40. Mechanism for the B(C6F5)3-catalyzed hydrosilation of unsaturated organic compounds ...... 91

99 Scheme 41. Activation of Et3SiH by borole 1-1 ...... 93

Scheme 42. Formation of the boraindne-silane adduct 4-1...... 94

Scheme 43. Wrackmeyer B-H-Si compound214...... 102

Scheme 44. Reactions of 1-4 with PPNCl in both the presence and absence of Et3SiH ...... 105

Scheme 45. Hydrosilation of t-butylethylene, 1,1-diphenylethylene, and cyclohexene...... 108

Scheme 46. Proposed synthesis of 5-3...... 112

Scheme 47. Retrosynthesis and suggested synthesis of 5-4...... 113

Scheme 48. Comparison of the photophysical properties of phenantrene, 9-aza-10- boraphenanthrene and 4a-aza-4b-boraphenanthrene...... 114

xix Scheme 49. Previously reported “B-N Boraindnes”...... 115

Scheme 50. Hypothetical reaction of 5-7 with H2 compared to reaction of 1-4 with H2...... 116

Scheme 51. Retrosynthesis of 5-7...... 117

xx List of Symbols, Abbreviations and Nomenclature

[X] concentration of X

[X]o initial concentration of X

{1H} proton-decoupled

˚ degrees

6-311 g(d) basis set with 6 core Gaussians, d-type functions

6-311+G(d,p) As above, with diffuse functions and p-type functions on hydrogen

Å angstrom

AN Acceptor Number (Gutmann-Beckett)

Ar aryl group

ASE aromatic stabilization energy atm atmosphere (pressure)

B3LYP Becke, three-parameter, Lee-Yang-Parr exchange-correlation functional br broad

Bu Butyl (-CH2CH2CH2CH3)

C Celsius

CA Child's Acidity ca. circa (approximately)

Calc'd calculated cf. confer (compare)

Cp cyclopentadienyl

Cp* pentamethylcyclopentadienyl

xxi δ Chemical shift in ppm (NMR)

Δ Deuterium d doublet

Δδ change in chemical shift

DEPT-Q Distortionless Enhancement by Polarization Transfer + Quaternary (carbons)

DFT Density Functional Theory

ΔG‡ Gibb's free energy of activation

ΔGo Gibb's free energy change

ΔH‡ enthalpy of activation

ΔHo enthalpy change

DiBAl Di-isobutyl aluminum

ΔS‡ entropy of activation

ΔSo entropy change

E Energy e.g. exempli gratia (for example)

EI electron impact

ε molar extinction coefficient

Et ethyl (-CH2CH3) et al. et alii (and others) etc. et cetera (and the others)

FIA fluoride ion affinity

FLP frustrated lewis pair

GCMS gas chromatography mass spectrometry

xxii h Planck's constant

HOMO highest occupied molecular orbital

HRMS high-resolution mass spectrometry

HSAB hard and soft acids and bases i.e. id est (that is) iPr isopropyl (-CH(CH3)2)

IR infrared

J joules

K Kelvin

Ka association equilibrium constant kB Boltzmann's constant kJ kilojoules kobs observed rate constant l wavelength

L Litre

λmax wavelength of maximum absorption

LUMO Lowest Unoccupied Molecular Orbital

M molar (moles per litre)

M metal (in a chemical formula) m multiplet m- meta-

MALDI Matrix-assisted laser-desorption ionization

Me Methyl (-CH3)

xxiii Mes Mesityl (2,4,6-trimethylphenyl)

MHz Megahertz min. minutes

µL microlitre mL millilitre mmHg millimetres of mercury (pressure) mmol millimoles mol moles

MS Mass spectrometry n- normal

NICS Nucleus-Independent Chemical Shift

NIR Near-infrared n JXY n-bond coupling constant for atoms X and Y nm nanometre

NMR Nuclear Magnetic Resonance o- ortho- p- para-

PAH polyaromatic hydrocarbon

PBE1PBE Perdew, Burke, Ernzerhof functional, modified by Adamo

Ph Phenyl (-C6H5) ppm parts per million

PPN+ bis(triphenylphosphine)iminium py pyridine

xxiv q quartet

R ideal gas constant

R typically an alkyl or aryl group, sometimes H (chemical formula)

ρ density

RT room temperature s seconds s singlet

SN2 2nd-order nucleophilic substitution t time in seconds t triplet t-Bu tertiary-butyl (-C(CH3)3)

TD-DFT Time-Dependent Density Functional Theory

THF tetrahydrofuran

TiPP 2,4,6-triisopropylphenyl

TOF time-of-flight tol-d8 toluene-d8

TZVP basis set

UV ultraviolet

Vis visual (light)

xxv List of Numbered Compounds in Chapters 1 and 2

O Me C6F5 Ph Ph F5C6 C6F5 C F C Ph Ph 5 6 F C B Ph B Ph B Me 5 6 B C6F5 F C Ph 5 6 C6F5 Ph 1-2 C F C6F5 1-1 Ph 1-1mes Me 6 5 1-2CO

F Ph Ar F F5C6 Ph Ar F B B B F5C6 B F 1-3 Ph Ph 1-5 Ph 1-4 C6F5

1-3CH3, Ar = p-C6H4CH3, 1-3CF3, Ar = p-C6H4CF3, 1-3F, Ar = p-C6H4F, 1-3C6F5 Ar = C6F5

F F F F Ph Ph Ph Me Ph SiMe3 F F Ph Ph Ph Sn Ph Zr SiMe B py 3 F F Li 2-1 2-2 1-6 C6F5 Li Me 2-3

F5C6 C6F5 F5C6 C6F5 F5C6 C6F5 Ph Me Ph F5C6 C6F5 F C C F F C Sn Zr 5 6 Sn 6 5 5 6 B C6F5 Cp Me 2-7 Cp Me Me Br 2-6 2-4 2-5

Me Ar Me F5C6 Ph Cp Cp F4 Ar Ar F5C6 Sn Ph Sn Zr Ar Zr 2-8 2-9 Me Me Cp Cp Ar = p-C H CH , 2-7CH , 6 4 3 3 Ar = p-C6H4CH3, 2-9CH3, Ar = p-C H CF 2-7CF 6 4 3, 3, Ar = p-C6H4CF3, 2-9CF3, Ar = p-C H F, 2-7F, 6 4 Ar = p-C6H4F, 2-9F, Ar = p-C H OMe 2-7OMe 6 4 Ar = p-C6H4OMe 2-9OMe Ar = C F 2-7C F , 6 5 6 5 Ar = C6F5 2-9C6F5

F C Cp 5 6 F F5C6 4 F4 F C 5 6 Zr F5C6 B 2-10 2-11 Cp Br

xxvi List of Numbered Compounds in Chapters 3 and 4

Ph Ph Ph Ph Ph Ph Ph Ph D D Ph H H Ph H D B B B Ph D B Ph Ph H Ph Ph Ph Ph Ph Ph Ph

cis-3-1 trans-3-1 cis-3-1D2 trans-3-1D2

F C C F Ph py Ph Ph py Ph 5 6 6 5 F5C6 C6F5 H H Ph H F5C6 H H H B B B Ph H B Ph Ph H C6F5 F5C6 C6F5 C F Ph Ph 6 5 C6F5 cis-3-1•py trans-3-1•py cis-3-2 trans-3-2

F5C6 F C F C F 5 6 F Ph Ph F5C6 F 5 6 F F F5C6 F F5C6 C6F5 F Ph Ph Ph Cl F H H B F B F B H B F F H C F OPh 3-3 3-4 3-5 3-6 6 5 C6F5

F F F F F F F F PPN F PPN F5C6 F5C6 F5C6 F F Si F SiEt3 B B B H F C F5C6 F5C6 5 6 H Cl H C F C6F5 C6F5 4-1 6 5 4-2 4-3 4-4

H Ph SiEt3 H Ph SiEt3 4-5 4-6

xxvii List of Numbered Compounds in Chapter 5

Ar C6F5 Ar I B C6F5 Ar F4 Ar C6F5 Ar B Zr B Ar B Cp Cp I 5-3 C F 5-1 5-2 6 5 F5 5-4 Br SnMe F 3 R' B Br 4 R' F4 Br B R H B R SnMe 1-4 H 1-4 Sn 3 N N B R" B B B Me Me R" 5-5 Br 5-7 5-8 Br 5-6 R' R'

R1-4 Br2B R' R' Br2B 5-12 B R1-4 SnMe3 B R1-4 R" N S R" N B R H B SnMe3 X 1-4 5-11 H R' 5-9 5-10 5-13 R' X

List of Numbered Intermediates

Ar Ar Ar Ar H Ar Ar H H H Ar Ar Ar H Ar Ar Ar B B Ar Ar B Ar H Ar Ar Ar B H Ar H I cis-II trans-II Ar cis-III

Ar Ar F Ar F ArF 4 F4 ArF F F Ar Ar Ar Ar Ar H F H Ar H H F4 B H B H B ArF B H ArF H ArF trans-III trans-IV cis-IV V

ArF ArF F F4 F4 Ar H F4 F F F H Ar Ar Ar Et Ar = -C6H5, -C6F5 H H ArF B B B F F Ar Et ArF Ar = -C6F5 VI trans-VII cis-VII

xxviii Chapter One: Introduction

1.1 Lewis Acids and Bases

“We are inclined to think of substances as possessing acid or basic properties, without having a particular solvent in mind. It seems to me that with complete generality we may say that a basic substance is one which has a lone pair of electrons which may be used to complete the stable group of another atom, and that an acid substance is one which can employ a lone pair from another molecule in completing the stable group of one of its own atoms. In other words, the basic substance furnishes a pair of electrons for a chemical bond, the acid substance accepts such a pair.”

- Gilbert N. Lewis, 1923

With these words Gilbert N. Lewis set forth a theory of acidity and basicity that has remained essential to the science of chemistry to this day.1 This idea was born out of the need for a more generalized concept than that of Brønsted-Lowry acids and bases, which was limited to the transfer of a proton, typically in aqueous solution.1-2 Since then, the idea has been further developed and enriched,2 but the basic principle remains the same: a Lewis base is an electron pair donor, and a Lewis acid is an electron pair acceptor.

Boron compounds of the type BX3 (X = H, F, Cl, Br, I, alkyl) were among the examples discussed by Lewis in the development of this theory,1 a consequence of their un-filled valence shells requiring a fourth pair of electrons to satisfy the octet rule. These Lewis-acidic boranes possess an empty p-orbital located on the boron atom into which a Lewis base may donate its electron pair to form a σ-bond, and the resulting compound is referred to as a Lewis acid-base adduct, or just an adduct. The basic electron pair most often originates from some non-bonding orbital, as in the cases of ethers, alcohols, amines, phosphines, sulfides, halides, etc. It is not

1 uncommon for the basic electron pair to come from a π-bonding orbital such as in olefins, alkynes3 and aryl groups,4 but these adducts tend to be reactive intermediates. Examples of boron adducts where the Lewis-basic electron pair originates from a σ-bond are also known.5-6

A simple depiction of the reaction between a borane and a Lewis base can be seen in

Scheme 1. Upon formation of the adduct the geometry of the borane changes from trigonal planar (where the average bond angle is 120˚) to tetrahedral (where the average bond angle is

109.5˚), bringing the boron-bonded groups closer together. This induces a certain amount of

“back strain” as these groups experience greater steric repulsion, so it follows that larger groups would make adduct formation less favourable than smaller groups. Steric repulsion is also possible between the groups on the base and on the acid (“front strain”), which can both slow the formation of the adduct as well as destabilize it. Therefore, front strain affects both the kinetics and thermodynamics of adduct formation.

B A B A

front back strain strain

Scheme 1. Depiction of a generic three-coordinate borane reacting with a Lewis base.

Another important aspect of adduct formation is the strength of the bond that is produced.2 In this instance a frontier orbital diagram is instructive: the electron pair to be donated by the Lewis base is located in its highest occupied molecular orbital (HOMO), which

2 combines with the lowest unoccupied molecular orbital (LUMO) to give a new filled bonding orbital and an empty anti-bonding orbital. For this combination to occur at all, the HOMO of the base and LUMO of the acid must have the appropriate symmetry. For example: a pz orbital would have a net zero overlap with a dxy orbital, and so a bond would not form; whereas a pz orbital would have a good overlap with a dz2 orbital, and so a bond would form. When symmetry does allow for bond formation, the strength of this bond is a function of the energy difference between the HOMO of the base and the LUMO of the acid; the greater this difference, the weaker the bond (Figure 1).

HOMO LUMO HOMO LUMO (base) (acid) (base) (acid)

strong adduct bond weak adduct bond

Figure 1. Molecular orbital (MO) depiction of Lewis acid-base adduct bond formation

Pearson’s hard and soft acids and bases (HSAB) theory7-8 provides a means to assess the relative energies of a base HOMO and an acid LUMO; by extension, it provides a means to assess the relative strength of the resulting acid-base bond. A “hard” acid or base is defined by high charge, small volume and low polarizability at the acidic or basic segment of the molecule; a “soft” acid or base is defined by low charge, large volume and high polarizability at the acidic

3 or basic segment. The charge at acidic centres is by definition positive, and basic centres are necessarily negatively charged. Hard acids prefer adduct formation with hard bases, and soft acids prefer soft bases; the closer an acid and base are in hardness, the closer their relative energies will be, favouring a more stable adduct.

Another feature of “hardness” is that it involves ionic bonding about the acidic or basic centre, while softness involves covalent bonding. In the context of Lewis acids, B-C and B-H bonds make for softer acids due to their high covalent character, while B-O, B-N, B-F, B-Cl and

B-Br bonds make for harder acids due to their high ionic character. Therefore trialkylboranes, triarylboranes and BH3 are considered soft, while B(OMe)3, BF3 and BCl3 are considered hard.

One must be cautioned against only considering electronegativity differences between atoms however, because the empty p-orbital on boron allows for π-bonding with lone pairs on adjacent atoms (increasing covalent character). For example, the trihaloboranes BX3 (X = F, Cl, Br, I) have a smaller difference in the B and X atoms proceeding from X = F to X = I, but the π- bonding interaction also becomes weaker as overlap between the orbitals on B and X worsens

9-10 (Figure 2). The net effect is that BX3 becomes a harder acid proceeding from X = F to X = I.

I F Cl Br B F B Cl B Br B I F Cl Br I

Hardness

Electronegativity Difference

Figure 2: Comparison of the hardness, electronegativity and orbital overlap of the trihaloboranes

4 1.2 Lewis Acidity Scales

In most cases it is easy to identify a Lewis acid, but the concept of Lewis acid strength is much more nebulous.9-11 Presumably stronger Lewis acids make more stable adducts, or are more capable of reacting with weaker Lewis bases. Unfortunately, the factors discussed above confound nearly every attempt to establish a universal scale of Lewis acid strength. Measuring it against adduct formation with a single Lewis base does somewhat dampen the impact of differences in steric factors (front strain in particular), but it is still complicated by the principles of HSAB theory. For example, BF3 forms more stable adducts with ethers than BH3, but for thioethers the opposite is the case;12 the choice of base can therefore affect the relative ordering of Lewis acid strength. For these reasons it has been argued that the strength of a Lewis acid should correspond to its ability to accept only an electron pair (i.e. electron pair affinity)9-10, but this is not necessarily a meaningful parameter for real Lewis acid/base reactions.

Despite the multi-dimensional nature of Lewis acidity, three semi-quantitative scales employing different reference bases have come into use over the past two decades. Fluoride ion affinity (FIA) is determined primarily through quantum-chemical calculations on energy of the

- - 13 reaction F3CO + LA → F2CO + LAF (where LA is a Lewis acid). Fluoride is chosen because its small size and high basicity make it reactive with nearly all Lewis acids, but the difficulty in calculating the electron affinity of F necessitates the use of the aforementioned F- exchange reaction. The scale is also adjusted for the experimentally known fluoride affinity of F2CO (49.9 kcal mol-1).

The other two Lewis acidity scales are based on nuclear magnetic resonance (NMR) methods. The Child’s acidity (CA) method consists of measuring the change in chemical shift

5 (Δδ) of the β-hydrogen in crotonaldehyde upon adduct formation (through the carbonyl oxygen)

14-15 with a Lewis acid (Scheme 2). This scale is referenced to BBr3, which is arbitrarily given a value of 1.00. The β-hydrogen chemical shift is the most sensitive to adduct formation, and is sufficiently removed from the centre of adduct formation so that the Δδ should result primarily from the change in the electronic environment, with the idea that stronger Lewis acids should remove more electron density and cause a larger Δδ. This notion is borne out by thermochemical measurements, which show a good correlation between observed heats of adduct formation and the Child’s Lewis acidity scale for a small set of Lewis acids.15

H3C

β-hydrogen H O H LA

Scheme 2. Adduct formation between crotonaldehyde and a Lewis Acid

Perhaps the most widely used Lewis acidity scale for boron Lewis acids11 is the

16-17 31 Gutmann-Beckett scale, which is based on the P Δδ of triethylphosphine oxide (Et3PO) upon adduct formation. This scale was created out of the application of the Gutmann Acceptor

Number (AN)16 scale, originally used to quantify the electrophilic properties of solvents, to

17 31 Lewis acids. The AN scale uses two reference points: the P δ of Et3PO in hexane (-41.0 ppm,

AN = 0) and in SbCl5 (-86.1 ppm, AN = 100), from which an acceptor number can be calculated.16 Alternatively, the 31P Δδ can be simply measured in the same solvent and used for comparison; this has the advantage of negating any differences in spectrometer calibration.

The agreement between the Gutmann-Beckett and Child’s acidity scales depends on the relative hardness of the acids being tested. Crotonaldehyde contains a C=O pπ - pπ double bond

6 that is highly covalent, whereas Et3PO contains a P=O dπ - pπ double bond that is much more ionic in character, making it a harder base. In cases where the hardness of a series of acids is variable, the two scales have shown opposite trends. A good example of this is shown by the

18 series of compounds of type (F5C6O)nB(C6F5)3-n where n = 0, 1, 2, 3 (Scheme 3); as the number of B-C bonds are exchanged for B-O bonds (n increases), the “hardness” of the Lewis acid increases because B-O bonds are more ionic in nature. Therefore the hard base Et3PO is able to form more stable adducts with higher values of n (AN increases with n), while the soft base crotonaldehyde forms less stable adducts (CA decreases with n). In cases where the hardness of the Lewis acids remains relatively constant, the two acidity scales typically agree. Taken together, these two scales can offer a good assessment of Lewis acidity with respect to both hard and soft bases.

F F F F O B F F F 3-n F F F n

n = 0 1 2 3

Scheme 3. Comparison of the CA and AN trends for (F5C6O)nB(C6F5)3-n where n = 0, 1, 2, 3

These methods tend to ignore the impact of back strain, so they overestimate the acidity of more sterically demanding Lewis acids. Marks et al. have shown that for larger boranes, the

Childs acidity values run counter to the enthalpies of adduct formation with crotonaldehyde.19

While calorimetric methods may provide the most accurate measurement of Lewis acidity, they are cumbersome to perform. A more convenient assessment comes from competition

7 experiments, wherein two Lewis acids compete for the same base. Assuming the activation barrier to the exchange is low enough, the equilibrium will unambiguously reflect the relative thermodynamic changes of the two Lewis acids on adduct formation. Furthermore, competition experiments are specific to the base in question, but this makes broader comparisons more difficult.

1.3 Applications of Boron Lewis Acids

It is difficult to overstate the importance of Lewis acids to organic chemistry, as they are employed in a wide variety of organic transformations.4, 20 Boron trifluoride alone has been used in the cleavage of ethers, Friedel-Crafts alkylations and acylations, cyclizations, rearrangements, aldol reactions, desilylations and destannylations.4 The other boron trihalides are used in the cleavage of ethers, acetals and esters. Boronic acids (RB(OH)2) and esters (RB(OR’)2) are used in Suzuki-Miyaura cross-coupling reactions,21-22 reactions which form carbon-carbon bonds and are among the most common chemical transformations performed in modern chemistry.21

Hydridoboranes (boranes containing a B-H bond) are used in hydroboration reactions,23-27 another very useful transformation since the B-C bonds can be elaborated into a myriad of functional groups.

Boron trihalides are very strong Lewis acids, but require very careful handling due to their volatility and the hydrolytic sensitivity of the boron-halogen bond. Early attempts to synthesize boranes of comparable Lewis acidity and easier usability focused on perfluoroalkyl

28-30 boranes (eg. B(CF3)3). Unfortunately these attempts failed because of the thermally-induced migration of a fluoride onto the boron centre, resulting in the release of a fluoro alkene or a reactive difluorocarbene. In 1963 Massey, Park and Stone reported 8 31-33 tris(pentafluorophenyl)borane, B(C6F5)3, an isolable white solid that is unreactive towards oxygen, tolerant to moisture, soluble in organic solvents and stable up to 270 ˚C. It is also a

11 strong Lewis acid, with a comparable Gutmann-Beckett AN to BF3.

Despite being an “ideal” Lewis acid, the chemical community did not recognise the potential of B(C6F5)3 until 1991 when Marks and Ewan independently reported its use as an initiator for group 4 metallocene-catalyzed olefin polymerization reactions. The early Massey and Park papers were cited only 25 times (excluding self-citations) until the 1990’s, but now a

Scifinder™ search turns up over 2700 citations, over 1000 of which are patents! As such, the

28, 34- applications of B(C6F5)3 are varied, and include: activation of transition metal pre-catalysts,

36 carboboration reactions,3, 37 catalysis of organic transformations,38 and “frustrated Lewis pair”

(FLP) chemistry39-40 (which will be discussed in more detail in Chapter 3).

Many of these uses for B(C6F5)3 have been discussed in several reviews, so the following discussion will focus on the most recent applications. A particularly intriguing one is the 1,1- carboboration of alkynes,3 wherein one of the alkyne carbons is inserted into a B-C bond of

B(C6F5)3 with concomitant migration of the substituent onto the other alkyne carbon (Scheme 4).

The first step of the mechanism is the adduct formation between the weakly basic alkyne and

B(C6F5)3, testifying to the strength of this Lewis acid. With larger alkyne substituents (e.g. R, R’

= aryl, alkyl), this transformation can take extended periods of time at elevated temperature to achieve even moderate conversion.41 However for terminal alkynes (i.e. R = H), 1,1- carboboration can take only a few minutes at room temperature.42-43

1,1-carboboration F5C6 R R R' + B(C6F5)3 (F5C6)2B R'

Scheme 4. General reaction scheme for 1,1-carboboration of alkynes 9

This reactivity was very recently applied to terminal propargyl esters with very interesting results.44 In this scenario, 1,1-carboboration is accompanied by a rearrangement to give the cyclic product shown in Scheme 5, with the carbonyl oxygen co-ordinated to the –

B(C6F5)2 group. If the resulting olefin is terminal (i.e. R’ = H), this compound can then be thermally rearranged to give what is formally a “1,3-carboboration” product. Both of these cyclic compounds can be used as allylation reagents with aldehydes to give almost exclusively anti-diastereomers. In this way a C6F5-substituted C3 fragment can be diastereoselectively coupled to aldehydes, though the necessity of installing the C6F5 group does limit the applicability of these transformations somewhat. It may yet be possible to install other functional groups with reagents of the type RB(C6F5)2, which have also been shown to undergo

1,1-carboboration reactions.

1,1-carboboration "1,3-carboboration" product product

F5C6 C6F5 F5C6 C6F5 O R' B(C F ) B C6F5 Δ B H 6 5 3 O O R O H R O R' = H R O R' C6F5

R"CHO R"CHO

OH O2CH2R OH O2CR R" R" R' C F 6 5 C6F5

Scheme 5. Formation of boron allylation reagents from propargyl esters and their diastereoselective reactions with aldehydes.

10 45 46 Cyclization of propargyl amides and esters in the presence of B(C6F5)3 has also been very recently reported, indicating the potential application to the preparation of heterocycles.

Terminal propargyl amides undergo cyclization (without 1,1-carboboration) at lower temperatures to form the zwitterionic oxazolium species shown in Scheme 6; at elevated temperatures (and if R’ = H), these can undergo a proton shift to give the B(C6F5)3 adducts of aromatic oxazoles.45 In the case of propargyl esters, cyclization occurs quickly at room temperature to give zwitterionic 1,3-dioxolium-borates.46 All of these reactions finish with the

B(C6F5)3 moiety coordinated to the cyclized product, indicating that it may be possible to make this process catalytic if B(C6F5)3 could somehow be released.

O R = alkyl, aryl O O B(C6F5)3 R 45-60 ˚C R Me R N B(C6F5)3 N R' = H R' 20-45 ˚C N R' = H, Me R' (F5C6)3B

O R' R = p-Tol, tBu B(C F ) R' = alkyl 6 5 3 O R O B(C6F5)3 20 ˚C R R' O

Scheme 6. Cyclizations of propargyl amides and esters promoted by B(C6F5)3.

Bis(pentafluorophenyl)boranes (RB(C6F5)2, R = H, halogen, alkyl, aryl) are another sub- class of fluoroarylboranes that have received much attention since their discovery. Foremost

47-49 among these is Piers’ borane, HB(C6F5)2, a powerful hydroboration reagent. In the solid state it exists as a dimer with the formula [(F5C6)B(µ-H)]2, but in solution it partially dissociates into

49 the monomeric form HB(C6F5)2. Piers’ borane has proven capable of quantitatively hydroborating even electron poor and sterically encumbered olefins that more traditional hydroborating reagents are unable to react with, due to its high Lewis acidity. However, the difficulty and cost49-52 of preparing Piers’ borane make it best suited for special cases only.

11 The alkylboranes that result from hydroboration with Piers’ borane are known to undergo retrohydroboration48 at mildly elevated temperatures (ca. 60 ˚C). Recently Dow Global

Technologies exploited this phenomenon to convert internal olefins to terminal olefins,52 which are important co-monomers in polyolefin plastics. An example of this is the conversion of trans-

4-octene to 1-octene (Scheme 7): after quantitative hydroboration of trans-4-octene with

HB(C6F5)2, the resulting alkylborane is isomerized (via retrohydroboration/hydroboration) at 60

˚C for 10 hours, giving almost exclusively the terminal alkylborane (the thermodynamically favoured product). This is then converted to 1-octene by heating in the presence of limonene, giving 1-octene in 45% yield.

limonene F F F F F F F F F

F F F F F F 60 ˚C F B F F 60 ˚C H F B B F F F F F F F F F + F F 1-octene F C trans-4-octene 5 6 B F5C6 + isomer

Scheme 7. Conversion of trans-4-octene to 1-octene using HB(C6F5)2

Another use of HB(C6F5)2 is the installation of –B(C6F5)2 units into different compounds.

Recent efforts have focused on the creation of vicinal phosphine-boranes from HB(C6F5)2 and a vinyl phosphine,53-56 resulting in an intramolecular (frustrated) Lewis acid-base pair (Scheme 8).

A particularly interesting example is endo-2-(dimesitylphosphino)-exo-3- bis(pentafluorophenyl)boryl-norbornane, depicted in Scheme 8; this compound has been shown

12 to readily activate both CO53 and NO54 gases to form a cyclic carbonyl and nitrosyl radical, respectively.

C6F5 C6F5 B CO C O Mes P B(C6F5)2 Mes + HB(C6F5)2

P(Mes)2 C6F5 P(Mes)2 C6F5 NO B endo-2-(dimesitylphosphino)- N exo-3-bis(pentafluorophenyl) P O boryl-norbornane Mes Mes

Scheme 8. Activation of CO and NO by an intramolecular FLP.

Piers’ borane has also revealed some fundamental bond activations that are possible with

57 B-H bonds. In an elegant study by Nikonov et al., it was shown that HB(C6F5)2 is capable of activating both Si-H and H-H bonds via σ–bond metathesis mechanism (Scheme 9), making it a catalyst for hydride exchange between silanes and dihydrogen. The same study also showed that the BD3-THF adduct is capable of these transformations.

F F F F F F F F F F F F H F F F R B R H + H B R H + H B F F F H F F F R = H, Et3Si F F F F F F F F F

Scheme 9. Activation of Si-H and H-H bonds by HB(C6F5)2

13 In a similar vein, it has been shown that H2 can add across the (alkyl)C-B bond of

58 RB(C6F5)2 (where R is an alkyl group). This was exploited to catalytically hydrogenate olefins using HB(C6F5)2: hydroboration of an olefin leads to the alkylborane RB(C6F5)2, which then reacts with H2 to release an alkane and regenerate HB(C6F5)2 (Scheme 10). The reaction conditions require high catalyst loading (20%), harsh conditions (140 ˚C, ~5 atm H2) and long reaction times (3-5 days), so this “metal-free” catalysis is still less attractive than transition metal-catalyzed hydrogenations. However, this study does provide a proof-of-principle for borane-catalyzed hydrogenation.

C6F5 H B

3 1 R R C6F5 4 1 R4 R R R2 R3 R2 H H

H2 3 R 1 R4 R R2 H B(C6F5)2

Scheme 10. Proposed catalytic cycle for the hydrogenation of olefins by HB(C6F5)2

1.4 Boroles

As the list of known organoboron compounds grew, chemists inevitably set their attention on cyclic boron compounds. Indeed, the insertion of this electron-deficient element into unsaturated organic frameworks has proven very fruitful, and there now exists much literature on borabenzenes59-65 (6-membered rings), borepines66-67 (7-membered rings), and their derivatives

(Scheme 11). Much of the interest in these compounds relates to their photophysical

14 properties61, 67-68 or use as ligands in transition metal complexes,69 but from the perspective of designing a strong Lewis acid, the 5-membered unsaturated boracycles known as boroles are much more appealing. This is because they feature an internal C-B-C bond angle of 108˚, close to the idealized bond angle of the tetrahedral centre (109.5˚) that would result from the formation of a borole adduct. In this way the “ring strain” in boroles provides a thermodynamic driving force for adduct formation, thus increasing its Lewis acid strength. Furthermore, boroles are anti-aromatic while their adducts are non-aromatic, meaning that the unfavourable aromatic stabilization energy of boroles is dissipated on the formation of an adduct, providing another thermodynamic driving force.

B B B

Borole Borabenzene Borepin

Scheme 11. 5-, 6-, and 7-membered unsaturated boracycles

1.4.1 Aromaticity and Anti-aromaticity

Because anti-aromaticity is a defining property of boroles it is necessary to introduce the concept of aromaticity, its measurement, and its impact on reactivity. Aromaticity is a phenomenon typically observed in conjugated organic ring systems that imparts them with a special stability beyond what is expected due to the resonance delocalization of electrons.70-71 Additionally, it results in the equalization of bond lengths,72-73 ring current effects in the NMR spectra of the compounds, and other special magnetic properties.70, 74 Aromatic compounds exhibit different reactivity from olefins and polyenes, such as electrophilic aromatic substitution rather than

15 addition. By a similar token, anti-aromatic systems possess a special instability, localized bonding that results in bond length alternation, and NMR and magnetic effects that are opposed to those of aromatic systems.

The Hückel rules offer a simple means by which to predict the aromatic status of a compound. The rules state that it must be planar, cyclic and fully conjugated (e.g. consisting of p-orbitals capable of overlapping with each other); if one or more of these conditions is not satisfied the compound will be non-aromatic. If all these conditions are met and the compound contains 4n+2 (where n is an integer) electrons in its π-system, it will be aromatic, and if it has

4n electrons it will be anti-aromatic. Therefore examples of aromatic systems include benzene, borabenzene, borepin, pyrrole, the cycloheptatrienyl cation and the cyclopentadienyl anion; examples of anti-aromatic systems include cyclobutadiene, borole, planar cyclooctatetraene, and the cyclopentadienyl cation (Scheme 12). These rules usually work well for monocyclic systems, but tend to break down for systems with more than three fused rings. In fact, the

Hückel rules are only theoretically justified for monocyclic systems.75

B B B H H

N H Aromatic Anti-aromatic

Scheme 12. Examples of monocyclic aromatic and antiaromatic compounds

16 The Hückel rules make the identification of aromatic and anti-aromatic systems straightforward in many cases, but the quantification of aromaticity is far more challenging.

There are several indices of aromaticity based on individual properties of aromatic compounds such as aromatic stabilization energy,74, 76 molecular geometry,72-73 and magnetic properties.

However the general consensus is that aromaticity is a multi-dimensional phenomenon because not all of these indices correlate with one another very well.72-74, 77 The most popular index of aromaticity is the nucleus-independent chemical shift (NICS)78 scale owing to the relative ease with which it can be computed.

NICS is a quantity that represents the shielding effects of aromatic compounds in an external magnetic field.74, 76, 78-79 When placed in a magnetic field, a “ring current” is induced in aromatic compounds and consequentially they receive an induced magnetic field (Figure 3);70 this occurs for anti-aromatic compounds as well, but the field lines are reversed. These fields can shield or deshield atoms depending on their position; NICS is a measure of the extent of shielding of a hypothetical nucleus at the centre of the ring system. For aromatic systems such as benzene this region is shielded, and the NICS value is negative (diatropic); for anti-aromatic systems such as borole this region is deshielded and the NICS value is positive (paratropic). The concept of NICS has undergone some refinement since its introduction, and it is now considered best to calculate the NICS of a nucleus 1 Å above the plane of the ring at the ring’s centre

(denoted NICS(1)). In this way, the paratropic contributions from the σ bonds are minimized.

This gives an isotropic NICS value that is an average of three diagonal shielding tensors (xx, yy, zz), but since the external magnetic field is applied perpendicularly to the plane of the ring (z direction), the out-of-plane component contains the most relevant information on aromaticity.80

17 induced induced magnetic magnetic field field H H H H H H H B H H H H

external magnetic field

Figure 3: Magnetic shielding lines for benzene and borole. Shielded regions (diatropic shift) are denoted by blue dots and deshielded regions (paratropic shift) are denoted by red dots.

1.4.2 Borole Lewis Acids

Returning to the discussion of boroles, there are several examples reported in the literature that have shown interesting reactivity as Lewis acids: pentaphenylborole (1-1),81-83 perfluoropentaphenylborole (1-2),84 1,2,3-triphenyl-1-boraindene (1-3) and perfluoro-1,2,3-triphenyl-1- boraindene (1-4),85 9-phenyl-9-boraindene (1-5)86 and perfluoro-9-phenyl-9-borafluorene (1-6),87 among others. Of these compounds, 1-1, 1-2, 1-3, and 1-4 are featured in this thesis, particularly

1-4.

Ph Ph Ph Ph Ph Ph B B B 1-1 Ph 1-3 Ph 1-5 Ph

F F F F C F F F F5C6 C6F5 5 6 F F C F5C6 F F 5 6 B C6F5 B B F F F C F C6F5 C F 1-2 6 5 1-4 1-6 6 5

Scheme 13. Borole-containing compounds featured in this thesis.

Not much chemistry has been done with 1-5, though it is known to form an η1-adduct with

Cp*Al(I).86 Its perfluorinated counterpart 1-6 does the same, though it has been explored more extensively due to its (assumed) greater Lewis acidity. By the Child’s acidity scale 1-6 is slightly more Lewis acidic than B(C6F5)3, which was confirmed with a competition experiment

88 88 with MeCN. Like B(C6F5)3 it is also capable of abstracting a methylide from both zirconium and scandium89 complexes.

Borole 1-1 was initially reported in the summer of 1969 by Eisch and co-workers,83 representing the first monomeric borole to be isolated.81 The anti-aromaticity of this compound was inferred from its generally high reactivity, and was confirmed by the much-later elucidation of its structure.90 One indication of the high Lewis acidity of 1-1 is its ability to form stable

81 adducts with weak bases such as diethyl ether (Et2O). In cases where adduct formation is not desired, such as the study of the redox and radical chemistry of boroles,91 this high Lewis acidity is more detrimental than it is beneficial. The Braunschweig group has shown that installing a mesityl (2,4,6-trimethylphenyl) group on the boron centre is an effective means by which to kinetically stabilize the borole ring. Borole 1-1mes does not form an ether adduct, though it is capable of forming adducts with stronger bases such as 4-methylpyridine (Scheme 14);92 a competition experiment with 1-1 shows that only the 1-1 adduct forms. These results demonstrate the impact of steric factors on Lewis acidity; the electronic structure of the borole rings in 1-1 and 1-1mes is very similar so the difference in Lewis acidity must originate in the greater size of the mesityl group.

19 Ph Ph Ph Ph Ph Ph Ph Ph Ph B Ph Ph Ph Ph + B Ph Ph Ph B Me Me B + Me N N Me 1-1 1-1mes Me Me

Scheme 14. Competition reaction between 1-1, 1-1mes and 4-methylpyridine.92 To be sure, this type of kinetic protection has been a popular strategy for stabilizing borole-containing compounds that are designed to have interesting photophysical properties.

Such compounds include the only known diborole compound,93-94 as well as a number of arene and heteroarene-fused boroles depicted in Scheme 15.95-97 In addition to the large mesityl group, the even larger TiPP group (2,4,6-triisopropylphenyl) has been successfully employed in some compounds. The Yamaguchi group recognised an additional advantage to the TiPP group on boron: it can serve as a real probe by which to verify NICS calculations.96 The methyne proton of the ortho isopropyl groups on TiPP is oriented above the borole ring, close to where the

“dummy atom” in NICS(1) calculations is positioned. It was found that the NICS values did in fact correlate with the measured 1H chemical shifts of the methyne protons for some of the compounds below, providing a rare experimental verification of the NICS method.

S S S TiPP R R B B H H B H B H H H H B H

O N

Piers, Araneda B B Mes Yamaguchi Mes

Scheme 15. Examples of arene- and heteroarene-fused boroles93-97

20 In an attempt to make an even more Lewis acidic borole, the Piers group synthesized perfluoro-pentaphenylborole 1-2, a deep purple, insoluble, moisture-sensitive solid.84 One of the most impressive demonstrations of this compound’s Lewis acidity came from its formation of an adduct with carbon monoxide (Scheme 16).98 This is significant not just because CO is an extremely weak σ-base, but also because reaction of CO with organoboranes nearly always results in insertion into the B-C bond to form a carbonyl. Though there are prior examples of organoborane-carbonyl adducts ((F3C)3BCO, (F5C2)3BCO, and (F7C3)3BCO), only 1-2CO can be generated by reaction by direct reaction of a Lewis acid with CO gas. Furthermore, 1-2CO is a stable solid at room temperature, compared to (F5C6)BCO which decomposes at -120 ˚C.

Adduct formation can be reversed by placing 1-2CO under vacuum or heating it to 60˚C.

Infrared (IR) and X-ray structural data indicate that the C-O bond in 1-2CO is shorter than in free CO, suggesting that the bonding to 1-2 is of a σ-type only. This contrasts to transition metal carbonyl complexes, which characteristically exhibit π-back donation into the π* orbital of the

CO ligand, resulting in a longer C-O bond. It is also worth noting that borole 1-1 forms an adduct with CO at -78 ˚C, but it decomposes even at -20 ˚C.

O + CO C F C6F5 6 5 C F5C6 (rt) F5C6 B C6F5 B F5C6 F C - CO 5 6 C6F5 C6F5 vac or 60 ˚C C6F5 1-2 1-2CO

Scheme 16. Formation of 1-2CO from 1-2 and CO.98

21 1.5 Scope of the Thesis

At this point there remains much literature to discuss so as to provide a complete context for the contents of this thesis. However, it is better to leave these discussions to the introductory sections of the chapters in which they are more specifically relevant. The work in this thesis is focused on the synthesis and reactions of boroles and boraindenes, with a heavier emphasis on the latter as they are the newer class of compounds.

Chapter 2 details the synthesis of boroles 1-1 and 1-2, and boraindenes 1-3 and 1-4.

Furthermore, a comparative assessment of the structure, Lewis acidity and anti-aromaticity of these compounds is discussed. The chapter finishes with an examination of the synthesis and

UV/Vis spectra of a series of boraindene derivatives, with an emphasis on the impact of various substituents on the electronic structure of the boraindene framework.

Chapter 3 begins with an investigation of the mechanism of dihydrogen activation by boroles 1-1 and 1-2. The outcomes from this are then applied to boraindene 1-4, which eventually leads to the study of this compound’s mediation of the hydrogenation of cyclohexene, as well as the reactivity of 1-4 towards cyclohexene.

Chapter 4 focuses on the activation of the Si-H bond in triethylsilane by boraindene 1-4 in both the solution and solid states. The chapter concludes with a preliminary catalytic study of hydrosilations of olefins by 1-4.

Chapter 5 is a summary of the major conclusions of the thesis as well as a short proposal for future directions with boraindene chemistry.

22 Chapter Two: Synthesis and Properties of Pentaarylboroles and 1-boraindenes

2.1 Introduction: Synthesis of Pentaphenylborole and Perfluoropentaphenylborole

The synthetic sequence for pentaphenylborole 1-1 reported by Eisch and co-workers in 198681 is still used today.90, 99 It begins with a reductive coupling of two diphenylacetylene molecules with lithium metal to give the dilithiated butadiene 2-1 (Scheme 17). While 2-1 may be isolated

83 as a yellow solid, it is synthetically more efficient to simply add Me2SnCl2 to give the stannole

2-2, an air- and moisture-stable crystalline solid. A stoichiometric transmetallation with PhBCl2 proceeds at room temperature over the course of a few hours to give the desired borole 1-1 as a deep blue solid. So long as air and moisture are excluded when necessary, this is a straightforward and high-yielding synthesis, with overall yields being typically 48-56% in our hands.

Ph Ph Ph Me Ph Ph Ph 2 Ph Ph Ph Ph Me2SnCl2 PhBCl2 Ph Ph Ph Ph + Li Sn B -2 LiCl -Me2SnCl2 Et2O 2 Li Li Me Ph 2-1 2-2 1-1

Scheme 17. Synthesis of 1-1 On the other hand, the synthesis of perfluoro-pentaphenylborole 1-2 is much less straightforward and requires significantly more effort.84 The necessary diarylacetylene

100-101 (C6F5)CC(C6F5) is not commercially available and must be prepared from C6F5MgBr and di-iodoacetylene,102 a volatile, toxic, shock-sensitive solid (Scheme 18).103 The reaction of

(C6F5)CC(C6F5) with lithium metal was avoided because of the potentially explosive loss of LiF that complicates the use of such lithiated organofluorine reagents. The necessary C4(C6F5)4

23 framework is thus constructed from the reaction of (C6F5)CC(C6F5) with Rosenthal’s pyridine- stabilized bis-trimethylsilyl acetylene zirconocene 2-3104-105 to give zirconacyclopentadiene 2-4.

Such zirconocenes are typically very good transmetallating reagents, but the extent of fluorination in 2-4 significantly attenuates the nucleophilicity of its Zr-C bonds. As a result, one of the few available synthetic paths forward is a copper-mediated transmetallation106 to tin using

Me2SnCl2. While this gives the fluorinated stannole 2-5 in good yield, the low nucleophilicity of the Sn-C(sp2) bonds remains problematic in the next synthetic step as well. Normally, boron-tin transmetallations proceed stoichiometrically under mild conditions,61-62, 107 as demonstrated in the synthesis of 1-1. But in this case it is necessary to heat 2-5 to 120 ºC in neat BBr3, a powerful Lewis acid, for two days in order to generate the bromoborole 2-6. Finally, treatment

108 of this compound with half an equivalent of Zn(C6F5)2 yields borole 1-2 as a deep purple solid.

It is of paramount importance that Zn(C6F5)2 be free of any donor solvents (such as diethyl ether) to ensure a clean reaction; not only could a donor solvent coordinate both bromoborole 2-6 and the target 1-2, but the B-Br of 2-6 is bond is susceptible to cleavage by ethers to form B-OR species.

TMS TMS Cl F C 2 n-BuLi pyridine 5 6 C6F5 + Zr Zr TMS py Cl THF F C C F TMS 2-3 5 6 Zr 6 5 - pyridine + Cp - TMS TMS Cp I I 2-4 CoCl2 C F C F + 6 5 6 5 Me2SnCl2 -Cp ZrCl 2 C6F5MgBr Et2O (2 eq) CuCl 2 2 THF, 80ºC

F C F C C F 5 6 C6F5 BBr3 5 6 6 5 F5C6 C6F5 0.5 [Zn(C6F5)2] (neat) F5C6 C F F C F C C F B 6 5 5 6 B C6F5 120ºC 5 6 Sn 6 5 -ZnBr2 1-2 C6F5 Br Me Me 2-6 2-5

Scheme 18. Synthesis of 1-2 24 2.2 Synthesis and Characterization of 1-boraindenes

The interesting properties and high reactivity of boroles 1-182, 99, 109-111 and 1-298, 110-112 (see chapters 1 and 3) prompted us to develop synthetic routes to new anti-aromatic organoboron species, namely boraindenes 1-3 and 1-4 (Scheme 19).85 Given the transmetallation-based syntheses of 1-1 and 1-2, it seemed obvious to adopt a similar strategy for the boraindene systems. One could envision generating boraindenes from either stannaindenes (2-7 and 2-8) or from zirconaindenes (2-9 and 2-10); zirconaindenes would potentially allow for synthesis of boraindenes either directly113 or via stannaindenes.

Ar Ar Me X4 X4 Ar Ar M Sn M Me + Me2SnCl2

Ar Ar = C6H5, X = H: 2-7 M = Li, MgBr X4 Ar = C6F5, X = F: 2-8 Ar B Ar

Ar = C6H5, X = H: 1-3 Ar X4 Ar = C F , X = F: 1-4 Ar Cp 6 5 X4 Ar Zr + Ar " " Cp ZrII Ar = C6H5, X = H: 2-9 Ar = C6F5, X = F: 2-10

Scheme 19. Retrosynthesis of boraindenes 1-3 and 1-4.

Because both boroles 1-1 and 1-2 involve tin – to – boron transmetallations, stannaindenes 2-7 and 2-8 are attractive targets. Several stannaindene frameworks are known,114-

116 all of which are generated from the appropriate styrenyl dilithium species (Scheme 20).

25 Unfortunately, the Tsuchiya115 and Saito114 systems involve the generation of the dilithium species at temperatures well above those required for the explosive elimination of LiF from flouroaryl lithium reagents, so 2-8 could not be reached this way. The synthesis of the Ashe stannaindenes116 is not conducive to installing the desired aryl substituents at the 2- and 3- positions, which are needed to prevent dimerization in the boraindene targets 1-3 and 1-4.113, 117-

118 Considering these limitations, the best route to the desired stannaindenes 2-7 and 2-8 is apparently from the zirconaindenes 2-9 and 2-10.

R Li Li

H Me H Me Bu Me

H Sn Me3Si Sn Ph Sn Me Me Me Ashe Tsuchiya Saito 1993 1993 2006

Scheme 20. Previously reported stannaindenes

Zirconacyclopentadiene moieties113, 119 are well-known in the literature and are frequently

II 120 generated from two alkynes plus a source of “Cp2Zr ” such as Negishi’s reagent; in the case of zirconaindenes 2-9 and 2-10, the alkynes would be a diarylacetylene and an aryne (Scheme 19).

Thermal decomposition of diaryl group IV metallocene complexes is known to generate the corresponding metallocene-aryne complex via abstraction of an ortho proton (Scheme 21),121-127 which can be converted to the metalloindenyl species by in situ reaction with an acetylene. In fact, 2-9 has been previously synthesized this way, using diphenylzirconocene and diphenylacetylene (vide infra).128 It was not known whether this reactivity could be applied to

26 the perfluorinated system 2-10, but it appeared that the reaction only required the availability of an ortho proton on the initial metallocene. Therefore Cp2Zr(o-C6HF4)2 was selected as a starting point for the synthesis of 1-4.

Ph Cp2Zr Ph Cp Ph Zr Cp2Zr H Ph Zr H 2 Cp2Zr Cp 2-9

Scheme 21. Mechanism of the formation of zirconaindene 2-9 from Cp2ZrPh2 and PhCCPh

2.2.1 Synthesis of 1,2,3-triphenyl-1-boraindene

With a procedure for the preparation of 2-9 in hand, the synthesis of 1-3 seemed imminently achievable. Diphenylzirconocene (Cp2ZrPh2) was first prepared from zirconocene dichloride and phenyllithium121 in essentially the same yield as reported (Scheme 22). Thermal decomposition of Cp2ZrPh2 in the presence of diphenylacetylene over the course of 24 hours gave 2-9 as a crystalline orange solid in good yield.128 It is worth noting that zirconocene aryne complexes have been shown to activate the C(sp2)-H bonds of toluene to give both para- and meta- (but not ortho) tolyl zirconocenes,121 potentially leading to the incorporation of methyl groups into the 4, 5, 6, and 7 positions of the zirconaindene framework. However, the lack of spectroscopic evidence for this indicated that this reaction pathway is not significantly competitive with the insertion of diphenylacetylene.

27 2 PhLi -40ºC -RT Cl Ph Cp THF Ph Ph Ph Zr Zr Ph Zr Cl -2 LiCl Ph 110 ºC toluene 78% 2-9 78% Cp

- Cp ZrCl Me2SnCl2 2 2 THF, 80ºC - Cp2ZrCl2

PhBCl2 Ph CH2Cl2, RT Ph Me Ph B Ph Sn 70% 1-3 - Me2SnCl2 50% 2-7 Ph Me

Scheme 22. Synthesis of 1-3

The target boraindene 1-3 was initially synthesized directly from 2-9 by the addition of

1.2 equivalents of PhBCl2. The solution immediately changed from orange to bright red, and after roughly 45 minutes at room temperature 1H NMR spectroscopy revealed that the only Cp resonance was that of Cp2ZrCl2. Removal of the solvent in vacuo gave a bright orange fluffy

solid. Unfortunately the Cp2ZrCl2 by-product proved too difficult to remove effectively; both 1-

3 and Cp2ZrCl2 sublimed around the same temperature (120 ºC) under dynamic vacuum (ca. 10 mtorr), and their solubilities turned out to be too similar for recrystallization to be efficient.

Additionally, 1-3 immediately loses its colour on contact with even dry Florisil™ (MgO:SiO2), presumably due to reaction with the surface –O-H bonds. Having exhausted the most obvious means of separation, the synthesis of 2-7 was sought instead.

Stannaindene 2-7 was synthesized by heating 2-9 in the presence of Me2SnCl2 (1.05 equivalents) for 24 hours. The Cp2ZrCl2 by-product was removed by passing the product mixture through Florisil, and pure 2-7 was obtained by re-crystallization from CH2Cl2/CH3OH.

The product is an air- and moisture-stable white solid, and it was characterized spectroscopically.

1 The H NMR spectrum (CD2Cl2) contains a single resonance for the SnMe2 protons at 0.60 ppm , 28 nearly identical to that for stannole 2-2 (0.64 ppm). The DEPT-Q spectrum is consistent with the structure of 2-7, displaying six resonances for quaternary carbons and ten resonances for aromatic C-H between 125 and 152 ppm; the SnMe2 signal is at -8.6 ppm. A single resonance in the 119Sn NMR spectrum can be found at -11 ppm.

Subsequently, 2-7 was combined with PhBCl2 in CH2Cl2 and the reaction stirred at room temperature for four hours. After removal of the solvent and Me2SnCl2 in vacuo, the crude product was re-crystallized from CH2Cl2 and hexanes, giving 1-3 as a fluffy orange solid in 70% yield. Unfortunately, crystals suitable for X-ray analysis could not be obtained, but spectroscopic data is consistent with the structure of 1-3. The 11B resonance contains a single, broad resonance at 58 ppm, close to that reported for 1-1 (65 ppm).90 The DEPT-Q spectrum contains thirteen C-H signals and seven quaternary carbon signals in the aromatic region, three of which are broadened (presumably) due to coupling with a neighbouring boron atom. The 1H

NMR spectrum consists of a series of multiplets in the aromatic region, and the relative integrations are consistent with the nineteen 1H nuclei in 1-3.

2.2.2 Synthesis of perfluoro-1,2,3-triphenyl-1-boraindene

85 As stated above, Cp2Zr(o-C6HF4)2 was selected as the starting point for the synthesis of 1-4 on the assumption that it should thermally decompose to a zirconocene-tetrafluorobenzyne complex.

The synthesis of Cp2Zr(o-C6HF4)2 was accomplished by first de-protonating 1,2,3,4- tetrafluorobenzene with n-butyllithium at -78ºC in THF, then slowly transferring this solution via cannula into a stirred, cold slurry of Cp2ZrCl2 (Scheme 23). Pure Cp2Zr(o-C6HF4)2 was obtained as an off-white solid in 46% yield following recrystallization from CH2Cl2/hexanes. It should be noted that crude Cp2Zr(o-C6HF4)2 of sufficient purity for the next synthetic step has been 29 obtained in greater than 80% yield on multiple occasions; recrystallization typically consumed nearly half of the crude yield and was often not worth the improvement in purity.

1/2 Cp ZrCl Cp 2 2 F5C6 o F4 F nBuLi -78 - 0 C (F5C6)CC(C6F5) 4 H Zr F5C6 -78oC Zr F Toleuene 4 H 110˚C 63 % 2-10 H THF - LiCl 2 46 % Cp

Me2SnCl2 CuCl THF, 80˚C - Cp2ZrCl2

F C BBr3 Me 5 6 0.5 Zn(C F ) F5C6 F5C6 F4 6 5 2 F4 CH2Cl2 F4 F C 5 6 B F5C6 B F5C6 Sn

95% C F 1-4 - 0.5 ZnBr2 92% 2-11 -Me2SnBr2 71% 2-8 6 5 Br Me

Scheme 23. Synthesis of 1-4

The structure of Cp2Zr(o-C6HF4)2 was confirmed both by NMR spectrometry and X-Ray crystallography. The 19F NMR spectrum contains the expected four signals of equal integration, and the 1H NMR spectrum contains only a singlet at 6.37 ppm (from the Cp rings) and a complex multiplet at 6.57 ppm (from the phenyl protons) that collapses to a singlet on decoupling fluorine. The structure determined from X-ray analysis is shown in Figure 4. The most notable feature is that the hydrogen atoms on the two phenyl rings are pointed towards each other, a somewhat unexpected result given the dipole moments of the rings. However, one of the rings is stacked in a face-to-face manner with another on a nearby molecule such that their dipoles are opposed (Figure 5); the shortest interatomic distance (3.5 Å) is between the para-fluorine of one ring and the ipso-carbon of the other. The angle between the planes of the two phenyl rings on the same molecule is 34º, and the remaining bond lengths and angles are otherwise unremarkable.

Figure 5. Depiction of the face-to-face interaction between two phenyl rings on different molecules of Cp2Zr(o-C6HF4)2

31 The synthesis of the fluorinated zirconaindene 2-1085 was accomplished by a method

128 nearly identical to that for unfluorinated 2-9. Heating Cp2Zr(o-C6HF4)2 and (C6F5)CC(C6F5) in toluene at 110˚C for forty hours gave 2-10 as the major product. Reduction of the solvent in vacuo allowed for direct crystallization from the reaction mixture, and after washing with hexanes, 2-10 was obtained as a yellow powder in 63% yield. The 19F NMR spectrum indicates

1 the presence of two inequivalent C6F5 rings in addition to four indenyl fluorines, and the H

NMR spectrum displays only the Cp signal at 6.57 ppm. Crystals suitable for X-ray diffraction analysis were obtained from toluene at -30ºC, and the structure is shown in Figure 6. The five- membered zirconacycle is somewhat distorted from planarity with a sum of internal angles of

538.8(6)º and a C11-C12-C13-C14 torsion angle of 10.10(4)º.

Figure 6. Thermal ellipsoid (50%) diagram of 2-10. Selected bond lengths (Å): Zr1-C14 2.282(4), C14-C13 1.414(5), C13-C12 1.483(5), C12-C11 1.350(5), Zr1-C11 2.307(4); Selected bond angles (˚)C14-Zr1-C11 75.14(14), C12-C11-Zr1 114.1(3), C11-C12-C13 119.1(3), C14- C13-C12 117.4(3), C13-C14-Zr1 113.1(3); Selected torsion angle (˚): C11-C12-C13-C14 10.10

With the difficulty of separating zirconocene dichloride from boraindene 1-3 in mind, the synthesis of stannaindene 2-885 was sought out. As expected, the Zr-C bonds of 2-10 proved too 32 weakly nucleophilic to undergo transmetallation with Me2SnCl2 unaided, so CuCl was included in the reaction mixture as a mediator. The excess Me2SnCl2 was removed by sublimation, and the Cp2ZrCl2 by-product was removed with Florisil. Pure stannaindene 2-8 was obtained after recrystallization from hexanes as an off-white solid in 71% yield. The 19F NMR spectrum contains a new set of ten signals corresponding to the two -C6F5 rings and the four indenyl

1 fluorine atoms of 2-8. The single H resonance for the Sn-Me2 group is found at 0.78 ppm, and the 119Sn resonance was not detected, likely due to extensive coupling to fluorine. X-ray crystallographic analysis was performed on crystals obtained by slow evaporation from CH2Cl2, and the structure is shown in Figure 7. The five-membered stannacycle is almost perfectly planar with a sum of internal angles of 539.8(6)˚. The indenyl fragment is also planar, with the largest torsion angle (C3-C4-C5-C6) being only 3.27º. The environment around tin is a distorted tetrahedron, stemming from the small C3-Sn1-C6 angle (81.71(14)˚) required to incorporate the

Sn atom into the ring.

Figure 7. Thermal ellipsoid (50%) diagram of stannaindene 2-8. Selected bond lengths (Å): Sn1- C3 2.162(3), C3-C4 1.335(5), C4-C5 1.493(6), C5-C6 1.403(5) Sn1-C6 2.138(4); Selected bond angles (˚): C6-Sn1-C3 81.71(14), C4-C3-Sn1 110.7(3), C3-C4-C5 119.5(3), C4-C5-C6 118.1(3), C5-C6-Sn1 109.8(3); Selected torsion angle (˚): C3-C4-C5-C6 3.27

The synthesis of boraindene 2-1185 was accomplished with a simple room-temperature transmetallation reaction between 2-8 and an excess of BBr3 in a minimal amount of solvent.

The unwanted Me2SnBr2 was removed by sublimation and 2-11 was obtained as a yellow powder after recrystallization from hexanes. The 19F NMR spectrum contains a new, yet familiar, set of ten signals, and the 11B NMR spectrum contains a single broad resonance at 61 ppm. Yellow crystals suitable for X-ray analysis were obtained from cold hexanes, permitting the elucidation of the structure of 2-8 (Figure 8).

Figure 8. Thermal ellipsoid (50%) diagram of boraindene 2-11. Selected bond lengths (Å): B15- C1 1.562(4), C2-C1 1.352(3), C3-C2 1.492(3), C3-C4 1.417(3), B15-C4 1.548(4), Br1-B15 1.878(3); Selected bond angles (˚):C4-B15-C1 105.2(2), C2-C1-B15 107.4(2), C1-C2-C3 111.7(2), C2-C3-C4 109.7(2), C3-C4-B15 106.1(2); Selected torsion angle (˚): C1-C2-C3-C4 1.47. Finally, the target boraindene 1-485 was made from the reaction of 2-11 with 0.5

108 equivalents of Zn(C6F5)2. Filtration was used to remove the resulting ZnBr2, and removal of the solvent yielded pure 1-4 in 95% yield. In cases where 1-4 was not pure, recrystallization

34 from hexanes was performed. Compound 1-4 is a red crystalline solid that, in contrast to 1-2, is readily soluble in a variety of organic solvents. The 19F NMR spectrum contains the expected

11 thirteen signals corresponding to the three -C6F5 groups plus the four indenyl fluorines. The B resonance is broad and appears at 62 ppm, a value intermediate between 1-2 (66 ppm)84 and perfluoro-9-phenyl-9-borafluorene (57 ppm).

Figure 9. Thermal ellipsoid (50%) diagram of 1-4. Selected bond lengths (Å): B1–C1 1.575(5), C1–C2 1.353(5), C2–C3 1.483(5), C3–C8 1.415(5), B1–C8 1.553(6); Selected bond angles (º): B1–C1–C2 108.3(3), C1–C2–C3 111.1(3), C2–C3–C8 109.9(3) C3–C8–B1 106.8(3), C8–B1–C1 103.5(3); Selected torsion (º): 5.2.

Crystals fit for X-ray diffraction were acquired from hexanes, and the structure is displayed in Figure 9. As with boroles 1-190 and 1-2,84 the aryl substituents are arrayed in a propeller-like fashion. The five-membered boracycle is in essence planar, with its sum of internal angles equalling 539.6(7)º. The fused six-membered ring is likewise planar with a sum of internal angles equal to 719.7º, and the angle between the planes of the rings is only 5.5º. The

35 area around the boron atom is also planar, with a sum of B-C angles equal to 359.9º. There is notable single-double bond alternation within the five-membered boracycle (Figure 10): the intraring B-C bonds (1.553 Å and 1.575 Å) are very similar in length to expected value (1.56 Å), the olefinic C=C bond (1.353 Å) is only slightly lengthened (1.32 Å), the C-C single bond

(1.483 Å) is slightly shortened (1.49 Å), and the fused C=C bond (1.415 Å) is slightly lengthened as well (1.40 Å). These deviations might appear to indicate a lack of delocalization around the five-membered ring, which is an expected property of anti-aromatic compounds.90, 95

In fact, a recent computational study has shown that for borole, artificially increased bond alternation corresponds to increased antiaromaticity as measured by nucleus independent chemical shift (NICS) values.95

1.398(5) 1.483(5) 4 2 1.49 1.40 1.353(5) 1.32 3 1.361(5) 5 1.415(5) 1.40 1.356(6) 1 1.40 1.369(5) 1.40 1.575(5) 8 1.40 6 1.56 B 1.553(6) 1.390(6) 1.56 7 1.40

Figure 10. Depiction of the bond length alternation in the indenyl moiety of 1-4 with measured bond lengths in blue and typical bond lengths in red (Å)

It is worth noting that the fused six-membered ring also displays some degree of C-C bond alternation. The longest bond is C3-C8 (1.415 Å), and going around the ring the rest are as follows (Figure 10): C3-C4 1.360, C4-C5 1.399, C5-C6 1.358, C6-C7 1.390, and C7-C8 1.369

Å. This implies that the electron delocalization around the ring is inhibited, and therefore its aromaticity is decreased. A similar phenomenon is observed for the fused six-membered rings of fluorinated borafluorenes.87

36 The bond length alternation seen in 1-4 stands in stark contrast to the solid-state structures of 1-1 and 1-2, both of which indicated some degree of delocalization around the borole rings. In the former case it has been shown that intermolecular π donation into the borole ring is the cause of the low bond length alternation;90 in the latter it is attributed to five-fold disorder in the crystal lattice.84 In the case of 1-4 however, the only significant intermolecular interactions are very short B-F contacts between each boron atom and three fluorine atoms (F11 and F19) on two different molecules: 2.90 Å and 3.12 Å, close in value to the intramolecular B-F contacts between boron and the ortho fluorines of the attached C6F5 group (2.87 Å and 2.92 Å)

(Figure 11). However, these short contacts do not seem to impact any bond lengths or induce pyramidalization about the boron center.

Figure 11: Depiction of the B-F contacts of 1-4 in the solid state. Selected B-F contact distances (Å) F5-B1 2.873, F9-B1 2.917, F11-B1 2.895, F18-B1 3.482, F19-B1 3.118. While the bond alternation observed in 1-4 is a predicted property of antiaromatic compounds,95 it should be noted the non-aromatic five-membered rings of the synthetic

37 precursors to 1-4 also exhibit such bond alternation; olefinic and C-C single bonds of zirconaindene 2-10 and stannaindene 2-8 are also very close to 1.35 Å and 1.48 Å, respectively.

We therefore endeavoured to probe the antiaromatic character of 1-4 (and 1-3) computationally using the established method of NICS calculations.74, 76, 80, 129

2.3 Assessing the antiaromaticity of 1-1, 1-2, 1-3 and 1-4

The structures of compounds 1-3 and 1-4 were optimized at the B3LYP/6-311g(d) level of theory using Gaussian 09, and the structures are depicted in Figure 12. The calculated structure of 1-4 is nearly identical to the one deduced from X-ray diffraction, and the calculated structure of 1-3 is also very similar. Both structures exhibit very similar bond-length alternation, with the bonds in 1-4 being slightly shorter than in 1-3 due to fluorination. Table 1 lists specific bond lengths in the indenyl moieties of the two compounds.

Figure 12. Optimized structures of 1-4 (left) and 1-3 (right)

38 Further evidence of the antiaromatic character of 1-3 and 1-4 was found by performing

76, 80, 130 NICS(1)zz calculations at the B3LYP/6-311+G(d,p) level of theory. NICS(1)zz calculations were chosen for computational simplicity and because they tend to correlate reasonably well with aromatic stabilization energies.80 The five-membered rings of both compounds were found to be slightly antiaromatic, with NICS(1)zz values of 28.1 ppm for 1-3 and 27.7 ppm for 1-4. For comparison, the same set of optimizations and NICS calculations were carried out on 1-1 and 1-2, yielding values of 25.3 and 32.0 ppm, respectively. The findings for the fluorinated systems 1-2 and 1-4 are qualitatively consistent with those of

Yamaguchi et al. who have shown that fusing benzene rings to boroles tends to dampen antiaromaticity;96 the findings for the unfluorinated systems 1-1 and 1-3 are not consistent with this. Furthermore, it seems that the aromaticity of the fused benzene ring is also diminished.

The fused six-membered rings of both compounds were also very weakly aromatic, having values of -14.7 ppm (1-3) and -8.5 ppm (1-4); for reference, the NICS(1)zz of benzene and hexafluorobenzene are -29.0 and -23.2 ppm, respectively.131

Table 1: Comparative bond lengths (Å) of the calculated structures of 1-3 and 1-4, and of the X- ray structure of 1-4

Bond 1-3 (calc) 1-4 (calc) 1-4 (meas) Δd (calc-meas) C8-B1 1.575 1.563 1.553 0.01 B1-C1 1.582 1.571 1.575 -0.004 C1-C2 1.369 1.362 1.352 0.01 C2-C3 1.499 1.492 1.483 0.009 C3-C8 1.416 1.422 1.415 0.007 C3-C4 1.384 1.374 1.360 0.014 C4-C5 1.408 1.410 1.399 0.011 C5-C6 1.386 1.379 1.356 0.023 C6-C7 1.408 1.408 1.390 0.018 C7-C8 1.386 1.374 1.369 0.005

39 While NICS values offer a convenient means by which to evaluate aromaticity and antiaromaticity from a theoretical standpoint, they should still be compared to experimental results. Antiaromaticity is expected to impart compounds with a significant degree of Lewis acidity in proportion to the aromatic stabilization energy (ASE); anti-aromatic Lewis acids form adducts that are necessarily non-aromatic, thereby losing the unfavourable ASE. Therefore a reasonable hypothesis is that NICS values (which correspond to ASE)74, 76 should correspond to an index of Lewis acidity such as the Gutmann-Beckett16-17 method.

2.4 Assessment of Lewis acidity

The Gutmann-Beckett16-17 and Childs14-15 methods provide simple, convenient ways to assess the

Lewis acid strength based on changes in chemical shifts (Δδ = δ(adduct) – δ(free base)) of a phosphine oxide and crotonaldehyde, respectively, on adduct formation with the compound in question. The greater the Lewis acidity, the more electron density is drawn away from the observed atom(s) in the acid-base adduct, resulting in a larger down-field shift in the NMR spectrum. As discussed in Chapter One, steric interactions can confound these measurements somewhat,34 but the borole and boraindene systems discussed here should be sterically similar enough that this is a non-issue.

Crotonaldehyde seemed to react with 1-3 and 1-4 in a more complicated way than simple adduct formation, so triethylphosphine oxide (Et3PO) was chosen to provide a consistent measurement of Lewis acid strength across compounds 1-1, 1-2, 1-3, and 1-4. In all cases,

31 Et3PO was combined with an excess of Lewis acid and the P spectra were recorded at room temperature in CD2Cl2. The ubiquitous acid B(C6F5)3 was also measured as a reference, giving a

40 132 Δδref = 26.6 ppm, consistent with that measured by Stephan et al. The order of Lewis acidity was found to be (from highest to lowest): 1-4 > 1-2 > 1-1 > 1-3; precise values are given in

Table 2. Perhaps the most significant result is that all four compounds displayed greater Lewis acidity than B(C6F5)3, even unfluorinated 1-1 and 1-3. This is likely due to both anti-aromaticity and the strain imposed by the five-membered ring. As expected, the fluorinated compounds 1-2 and 1-4 have higher Lewis acidities than their unfluorinated counterparts 1-1 and 1-3. However, the relative Lewis acidities of boroles 1-1 and 1-2 compared to boraindenes 1-3 and 1-4 are unexpected. Borole 1-1 is a stronger Lewis acid than boraindene 1-3, but the opposite is true in the fluorinated systems; boraindene 1-4 is a stronger Lewis acid than borole 1-2 using the

Gutmann-Beckett measure of LA strength. Steric considerations cannot explain this trend, nor do the NICS values discussed above.

Table 2: Gutmann-Beckett Lewis Acid Strengths and NICS(1)zz of 1-1, 1-2, 1-3, and 1-4 Compound 1-1 1-2 1-3 1-4 Δδ (ppm) 28.0 29.1 27.1 30.1 Δδ/ Δδref* 1.05 1.09 1.02 1.13 NICS(1)zz** 25.3 32.0 28.1 27.7 * Δδref = 26.6 ppm for B(C6F5)3 ** For the 5-membered ring, in ppm

The above indicates a lack of correlation between Lewis acidity and anti-aromaticity as measured by the Gutmann-Beckett and NICS(1)zz indices for boroles and boraindenes.

However, the high Lewis acidity and moderate anti-aromaticity of boraindenes warranted further investigation of this class of compounds, and so the next section discusses the manipulation of the electronic structure of boraindenes through chemical modification.

41 2.5 Synthesis of Boraindene Derivatives

The electronic properties of organic molecules can often be manipulated through modification of their structures. Indeed, the synthetic route described previously allow for such modification of boraindenes with relative ease due to its modular nature. Different groups at the 2- and 3- positions may be implemented with the appropriate choice of diarylacetylene, and different groups on boron may be introduced with the appropriate organometallic reagent (preferably an organozinc or organocuprate133) (Scheme 24). Modification of the 4 through 7 positions on the indenyl fragment is somewhat more limited, given the potential of asymmetric zirconocene- aryne complexes to give mixtures when reacted with acetylenes. Given the relative ease with which the substituents at the 2- and 3- positions may be modified and the potential impact on the electronic structure this might have, we began the extension of this class of compounds with the simple replacement of diphenylacetylene with para-substituted diarylacetylenes.

R R"2,4 R R" R R" M(R')n + R + M = Zn, n = 2 Zr B R B H M = Cu, n = 1 R 2 R' Cl/Br

Scheme 24. Retrosynthesis of boraindene derivatives A variety of para-substituted diaryl acetylenes were synthesized using a modified

Sonagashira coupling procedure, wherein calcium carbide (CaC2) and water were used to

134 generate acetylene gas. The para-substituents include both electron withdrawing (-F, -CF3) and electron donating (-CH3, -OCH3) groups (Scheme 25). In addition, (C6F5)CC(C6F5) was included in the acetylene “family” because of its availability in our lab. The zirconocene

Cp2ZrPh2 was chosen over Cp2Zr(o-C6HF4)2 because the former can be safely prepared on much

42 larger scales than the latter. The following synthetic steps followed virtually identical conditions utilized in the synthesis of 1-3.

Ar Ar Cp Ar Me Ar Cp2ZrPh2 Me2SnCl2 PhBCl2 Ar Ar Zr Sn CH Cl Ar B Tol, 110 oC o 2 2 Ar THF, 80 C, RT 20 hr Cp 24 h Me Ph

Ar = p-C6H4CH3, 2-9CH3, 83% 2-7CH3, 51% 1-3CH3, 65% Ar = p-C6H4CF3, 2-9CF3, 80% 2-7CF3, 64% 1-3CF3, 55% Ar = p-C6H4F, 2-9F, 98% 2-7F, 44% 1-3F, 61% Ar = p-C6H4OMe 2-9OMe 98% 2-7OMe 0% Ar = C F 2-9C F 93% 2-7C F , 72% 6 5 6 5 6 5 1-3C6F5 42%

Scheme 25. Synthesis of boraindene derivatives The zirconaindenes were all prepared in good to excellent yields, all of which were characterized by NMR spectroscopy. Crystals suitable for X-ray analysis were obtained for 2-

9CH3 and 2-9C6F5 derivatives (Figure 13 and Figure 14, respectively). The structures do not differ in any meaningful way from each other or from 2-10.

Figure 13. Thermal ellipsoid (50%) diagram of 2-9CH3. Selected bond lengths (Å): Zr1-C4 2.2697, Zr1-C1 2.2729, C1-C2 1.3655, C2-C3 1.4880, C3-C4 1.4183; Selected bond angles (º): C1-Zr1-C4 78.9, Zr1-C1-C2 111.0, C1-C2-C3 120.3, C2-C3-C4 119.8, C3-C4-Zr1 109.7; Selected torsion (º): C1-C2-C3-C4 6.9.

Figure 14. Thermal ellipsoid (50%) diagram of 2-9C6F5. Selected bond lengths (Å): Zr1-C2 2.2606(13), C2-C7 1.4051, C7-C14 1.4714, C14-C15 1.3565, Zr1-C15 2.2859(13); Selected bond angles (º): C2-Zr1-C15 76.6, Zr1-C2-C7 112.7, C2-C7-C14 117.7, C7-C14-C15 120.7, C14-C15-Zr1 112.1. Selected torsion (º): 4.0. The stannaindenes were synthesized in moderate yields, though analysis of the reaction mixtures indicated that conversions were nearly quantitative for all derivatives. The most probable cause of loss is therefore recrystallization, conditions for which have yet to be optimized. Additionally, isolation of 2-7OMe presented an unexpected challenge: this derivative in particular is apparently sensitive to –OH bonds. Even when the work-up for 2-7OMe was performed under inert, dry conditions, it decomposed on passing through Florisil. Given the acid sensitivity of Sn-C bonds,81 it seems that the –OMe groups impart enough basicity to the sp2 carbons next to the tin atoms to deprotonate the surface –OH groups of Fluorisil.

The other four stannaindene derivatives displayed NMR spectra that are consistent with

119 1 their structures. Of worthwhile note are the Sn{ H} spectra of 2-7F and 2-7CF3, which both

6 feature long-range coupling to fluorine; the signal for 2-7F at -11.9 ppm is a doublet with JSnF =

44 7 6.9 Hz and the signal for 2-7CF3 at -4.3 ppm is a quartet with JSnF = 4.6 Hz. All four of these derivatives were analyzed by X-ray diffraction, and their structures are depicted in Figure 15,

Figure 16, Figure 17, and Figure 18.

Figure 15. Thermal ellipsoid (50%) diagram of 2-7CH3. Selected bond lengths (Å): Sn1-C1 2.147(5), C2-C1 1.355(8), C3-C2 1.512(7), C3-C4 1.414(8), Sn1-C4 2.134(6); Selected bond angles (˚): C4-Sn1-C1 84.0(2), C2-C1-Sn1 109.6(4), C1-C2-C3 119.0(5), C2-C3-C4 119.5(5), C3-C4-Sn1 107.5(4) ; Selected torsion angle (˚): C1-C2-C3-C4 3.5.

Figure 17. Thermal ellipsoid (50%) diagram of 2-7F. Selected bond lengths (Å): Sn1-C1 2.153(5), C2-C1 1.330(7), C3-C2 1.503(7), C3-C4 1.398(7), Sn1-C4 2.135(6); Selected bond angles (˚): C4-Sn1-C1 82.7(2), C2-C1-Sn1 110.1(4), C1-C2-C3119.8(5), C2-C3-C4 118.5(5), C3-C4-Sn1 108.9(4) ; Selected torsion angle (˚): C1-C2-C3-C4 1.65.

Figure 18. Thermal ellipsoid (50%) diagram of 2-7C6F5. Selected bond lengths (Å): Sn1-C3 2.162(5), C3-C4 1.349(6), C4-C5 1.476(7), C5-C6 1.407(7), Sn1-C6 2.130(5); Selected bond angles (˚): C3-Sn1-C6 82.75(19), C4-C3-Sn1 108.5(4), C5-C4-C3 121.4(4), C6-C5-C4 117.8(4), C5-C6-Sn1 109.3(4) ; Selected torsion angle (˚): C1-C2-C3-C4 1.7.

46 The structural features of the stannaindene derivatives are largely what would be expected based on the earlier characterization of 2-8. Nevertheless, there are some interesting points to make about the above structures. The fluorine atoms of stannaindene 2-7CF3 are disordered across 1.33 positions in both –CF3 groups. This, in part, allowed the molecule to crystallize such that only half of a molecule constitutes the asymmetric unit, with a mirror plane splicing the molecule along the indenyl moiety. The unit cell (orthorhombic) is likewise more symmetric than those of the other stannaindenes (monoclinic). On the other hand, stannaindene

2-7C6F5 is the only derivative to crystallize with two molecules in the asymmetric unit, with the orientation of the –C6F5 rings being the only difference between them.

Figure 19. Thermal ellipsoid (50%) diagram of 1-3C6F5. Selected bond lengths (Å): B1–C1 1.585(5), C1–C2 1.349(5), C2–C3 1.491(4), C3–C8 1.416(5), B1–C8 1.561(6); Selected bond angles (º): B1–C1–C2 108.4(3), C1–C2–C3 111.6(3), C2–C3–C8 109.6(3) C3–C8–B1 107.4(3), C8–B1–C1 103.1(3); Selected torsion (º): 0.02.

47 The boraindenes were synthesized in moderate yields, again with recrystallization being the source of product loss. All of the derivatives except for 1-3C6F5 appeared as fluffy solids that were slightly different shades of red, as compared to the orange parent compound 1-3. The 11B resonance appeared as a broad signal at 65 ppm for all boraindene derivatives, except 1-3C6F5 which appeared at 63 ppm. It was also this yellow-orange derivative that was structurally characterized by X-ray diffraction, as shown Figure 19.

Figure 20. Depiction of the dimeric, face-to-face stacking of 1-3C6F5 in the solid state.

The structure of 1-3C6F5 is very similar to the structure of 1-4; the bond lengths in the five-membered boracycle are nearly identical between the two molecules, the indenyl moiety is planar, as is the environment around the boron atom. The fused six-membered ring exhibits some C-C bond length alternation, though not to the extent as seen in 1-4. There is a notable difference in the solid-state packing however; 1-3C6F5 crystallizes in a series of dimers with the

48 indenyl moieties aligned in an antiparallel, slip-stacked way with respect to each other (Figure

20). The shortest B-C contacts between molecules are 3.238 Å and 4.097 Å, the former being much shorter than the analogous contacts in the solid-state dimers of 1-1 (3.635 Å).

2.6 Electronic Properties of Boraindenes

The UV/Vis absorption spectra of organic compounds provide a simple means by which gain insight into their electronic properties. Molar absorption coefficients and HOMO-LUMO gap energies, two parameters that are of significance to organic electronic devices,79 can be readily quantified with this technique. Furthermore, by comparing the UV/Vis spectra of structurally similar compounds, one can infer the impact of small structural changes on the electronic properties of compounds. In this section the UV/Vis spectra of the aforementioned boraindenes are presented and the impact of their structural differences on their electronic properties is discussed.

-4 The UV/Vis spectra of 1-4, 1-3 and its derivatives were recorded at ~ 10 M in CH2Cl2 and are displayed in Figure 21; the extreme water sensitivity of these compounds thwarts measurements at lower concentrations. All six boraindenes have a low energy, weak transition with a λmax in the 440 – 500 nm region, comparable to the ladder dibenzodiborole reported by

Araneda and Piers.93 Such transitions are typical of borole-containing compounds,93, 95-97, 135-137 though all are blue-shifted relative to those of boroles 1-1 (560 nm)90 and 1-2 (530 nm).84 This indicates that the HOMO-LUMO gap of 1-boraindenes is larger than that of boroles, an interesting result given that the extension of π systems nearly always leads to a lowering of the

HOMO-LUMO gap in aromatic systems.79, 138 Upon further consideration this result should be

49 expected; aromatic systems achieve lower HOMO-LUMO energy when conjugation is extended because this increases the value of the resonance stabilization energy of the system.

Antiaromatic systems behave in the opposite way, as extending conjugation leads to less favourable resonance stabilization energy; extension of antiaromatic systems effectively increases the number of localized (or at least less-delocalized) double bonds, as evidenced by the bond alternation discussed above.

Figure 21. UV/Vis spectra of boraindenes 1-4, 1-3, 1-3CH3, 1-3F, 1-3CF3 and 1-3C6F5 in CH2Cl2. Inset: expanded region from 400-650 nm.

As with boroles 1-1 and 1-2, the λmax of the low-energy transition of fluorinated 1-4 is slightly blue-shifted relative to its unfluorinated analogue 1-3. The difference between the two

139 boraindenes’ λmax values is only 10 nm, compared to ca. 30 nm for boroles 1-1 and 1-2.

Regarding the other 1-3 derivatives, a notable trend emerges among the low-energy λmax (Table

50 3): as the electron-withdrawing ability of the aryl substituents increases, λmax shifts towards the blue. This is a commonly observed phenomenon among conjugated organic systems: increasing the degree of charge-transfer within a molecule upon light absorption lowers the energy of the

HOMO-LUMO transition. Boraindene 1-3CH3 serves as a good example in this series as the electron-rich tolyl groups would allow for the greatest degree of charge-transfer to the electron- deficient boron centre on which the LUMO is situated, and it indeed has the most red-shifted

λmax at 485 nm.

Table 3. Onsets of absorption, HOMO-LUMO gap energies, λmax and of boraindene derivatives

Compound Onset of HOMO-LUMO λmax εmax absorption /nm Energy /eV /nm /Lmol-1cm-1 1-4 565 2.19 465 900 1-3 580 2.14 475 1300 1-3CH3 600 2.07 485 1700 1-3F 590 2.10 475 850 1-3CF3 570 2.18 465 1000 1-3C6F5 535 2.32 445 860

The molar extinction coefficients were estimated from single concentrations, so precise conclusions about their relative values are not possible at this point. They are all small (ca. 850-

1700 Lmol-1cm-1), a typical feature of the symmetry-forbidden transitions of boroles. The low absorptivity of these compounds in the visible region precludes them from potential use in organic photovoltaic devices, though they may yet find use in organic field effect transistors.140

The HOMO-LUMO energies all occur in a narrow range of 2.1-2.3 eV, implying that they are semiconducting small molecules.

To gain further insight into the electronic structure of boraindenes we performed TD-

DFT calculations on 1-3 at the B3LYP/6311+G(d,p). The calculated and measured UV/Vis spectra both exhibit a very broad, weak low-energy absorption (ca. 400-600 nm) and two more 51 intense, high-energy absorption (ca. 300-400 nm and 250-300 nm) (Figure 22). The relative and absolute intensities of the absorptions are in good agreement between the two spectra; the most notable difference is that the absorptions in the calculated spectrum are red-shifted by about 30 nm relative to the measured spectrum.

Figure 22. Calculated (top) and measured (bottom) UV/Vis spectra of 1-3 and Kohn-Sham orbital surfaces of the HOMO and LUMO of 1-3.

The lowest energy transition corresponds to the HOMO to LUMO excitation, with a calculated energy of 2.35 eV, close to that measured from the onset of absorption in the experimental spectrum (2.14 eV). The HOMO is a π-type orbital that lies primarily on the indenyl moiety with significant contributions from the phenyl rings and the 2- and 3- positions

52 but no contributions from boron nor the attached phenyl ring. The LUMO is also a π-type orbital and shows a large contribution from the p orbital of boron with additional contributions from the rest of the indenyl moiety and the phenyl ring on boron. Because the HOMO and LUMO both lie on similar portions of the molecule we can rule out a charge-transfer absorption (which sometimes results in very broad bands). Furthermore, both the ground and excited states are singlet states, meaning that the transition between the two is spin-allowed. The transition may be symmetry forbidden, which would account for the weakness of the absorption, but not its broadness.

Nonetheless, the depictions of the HOMO and LUMO provide some insight as to why the energy of this transition was altered through substitution at the 2- and 3- positions on the indenyl moiety. Because the HOMO lies much more on the phenyl rings at the 2- and 3- positions than does the LUMO, we can surmise that the HOMO would be primarily affected by modifying these substituents. Electron-withdrawing substituents would be expected to lower the energy of the HOMO (as they often do for conjugated organic systems)141 and therefore increase the

HOMO-LUMO gap, which is consistent with our experimental observations.

Cyclic voltammetry would allow for the elucidation of the energies of the HOMO and

LUMO through measurement of the boraindenes’ redox potentials. Unfortunately, both 1-3 and

1-4 proved to react quickly with stoichiometric amounts of the electrolyte [Bu4N][PF6]. Another

142 electrolyte, [Bu4N][B(C6F5)4] was prepared according to modified literature procedures, and it showed much better stability towards the boraindenes. Unfortunately, under the CV cell conditions there was still a visible loss of the boraindene’s colour during the measurement, and so meaningful data could not be obtained.

53 2.7 Conclusions

A series of novel, five-membered unsaturated boracycles known as boraindenes were synthesized and characterized. Perfluorinated 1-4 and its unfluorinated counterpart 1-3 proved to be antiaromatic as evidenced by bond alternation in the indenyl moieties and NICS(1)zz calculations. The Lewis acidity of boraindenes 1-3 and 1-4, as well as boroles 1-1 and 1-2 was assessed by the Gutmann-Beckett method, and all four compounds proved to be stronger Lewis acids than B(C6F5)3. The order of Lewis acidity is 1-4 > 1-2 > 1-1 > 1-3, which does not correspond with the NICS(1)zz values. However, a more thorough study of the indices of antiaromaticity and Lewis acidity may yet reveal a relationship between the two phenomena.

A series of derivatives of 1-3 with varying aryl substituents at the 2- and 3- positions were also prepared and characterized. The UV/Vis spectra of these derivatives indicated a marginal impact of said aryl substituents on the HOMO-LUMO energy difference, with more electron-withdrawing substituents leading to higher energy differences. This series of compounds could also serve to expand the investigation of boraindene antiaromaticity and Lewis acidity.

Chapter Three: The Activation of Dihydrogen by Boroles and Boraindenes

3.1 Introduction: Activation of Dihydrogen by Pentaarylboroles

The simplest molecule consists only of the most abundant element in the universe, and as such dihydrogen (H2) has drawn the attention of scientists across many disciplines. Chemists in particular have spent an enormous effort studying how and why H2 may be used in bond- transforming reactions, namely its addition to unsaturated organic functions as well as the hydrogenolysis of many metal-element single bonds.143 The high bond strength and low polarity of dihydrogen has presented chemists with the interesting challenge with regard to its cleavage and delivery, a challenge that has largely been met using transition metal compounds. These compounds are known to activate dihydrogen by a variety of mechanisms, including oxidative addition, 144-145 σ-bond metathesis,146-147 electrophilic 1,2-addition148-149 and deprotonation150-152

(Scheme 26).

H H2 + Mn Mn+2 oxidative addition H

H2 + M L M H + H L σ-bond metathesis

H H H2 + M E electrophilic 1,2-addition M E

H M + B M H + BH deprotonation H

Scheme 26. Modes of activation of dihydrogen by metals

55 While the high catalytic activity of transition metal compounds towards H2 utilization has earned them a significant place in the chemical industry, they are plagued by high costs and toxicity issues. The response of the chemical community has thus been to seek “metal-free”

153 methods for the activation and delivery of H2 to substrates of interest. Main group element compounds that do this are less common, but a recent body of literature has grown out of the seminal discoveries of Power et al.154 which suggests that such compounds can cleave dihydrogen. Such activation commonly involves the synergistic depopulation of the H-H σ bonding orbital and the population of the H-H σ* antibonding orbital. Take the example of stable singlet carbenes that Bertrand and co-workers have investigated.155 These compounds heterolytically cleave the H-H bond, which is polarized by donation of carbene electrons into the

σ* orbital followed by transfer of hydride to the carbene carbon. Unfortunately, the irreversible nature these reactions thwarts the catalytic delivery of dihydrogen to other substrates.

Another approach to the problem of metal-free dihydrogen activation relies on the combination of a Lewis acid and Lewis base that are both too sterically encumbered to form an adduct.39 Termed “frustrated Lewis pairs” (FLPs), these systems have gained widespread

156 attention since the initial report of their reversible H2 activation. The acids are nearly always perfluoroaryl boranes of high Lewis acid strength (namely tris(pentafluorophenyl)borane,

32, 157 B(C6F5)3), but the bases allow for a great degree of variability and now many examples

39 t exist in the literature. When the base is a bulky phosphine, PR3 (e.g. R = Bu, Mes), computational investigations into the mechanism support the idea that the acid-base pair forms an “encounter complex” held together by weak van der Waals interactions (Scheme 27).158-161

This complex features a pocket into which H2 can diffuse and then be heterolytically cleaved by an electron-transfer mechanism.161 There are only a few experimental investigations into this

56 mechanism,162-163 none of which have found evidence for (nor against) the encounter complex, though the computational support is strong.

F F F F F F CH3 CH3 H3C CH F F 3 F F H3C CH CH 3 σ∗ 3 F CH F 3 B H H P CH3 B H F σ H + P CH3 F CH3 F F F F CH3 FF CH F F H3C 3 CH CH H3C 3 F F 3 CH F 3 F F F F F

Scheme 27. FLP-type activation of dihydrogen by B(C6F5)3 and P(t-Bu)3

One could envision another mechanism in which H2 first interacts with the empty orbital on a strong Lewis acid, and is subsequently deprotonated by a base in the second step. Such a

164 borane-H2 “adduct” has been shown to be energetically feasible for B(C6F5)3 and may indeed play a role in FLP systems where the encounter complex would be less favoured than for borane/phosphine systems. Examples of these systems include those where the base is an

165 166 imine or a carbene, which feature lower symmetric compatibility with B(C6F5)3 and as such have fewer van der Waals interactions. It is also worth pointing out that this process is reminiscent of the binding of H2 and subsequent de-protonation from transition metal complexes

(Scheme 26).150-152

The notion of Lewis acid-H2 adduct formation received solid experimental support when the Piers group observed that pentaphenylborole83, 118, 167 (1-1) and perfluoropentaphenylborole84

(1-2) react with H2 to form mixtures of cis- and trans-pentaphenyl-1-boracyclopenta-3-enes (3-1

110 and 3-2) (Scheme 28). In the absence of a base, the most obvious explanation is that the H2

57 must first interact with the empty orbital on boron. The Lewis acidity of the compound also seems to play a role, given that perfluorinated 1-2 reacts nearly instantly while unfluorinated 1-1 reacts over the course of 4-5 hours at room temperature.110 Perhaps the most surprising feature of this reaction was that the trans isomers were the major products (ratios given in Scheme 28), raising the question as to how H2 could end up on opposite faces of the ring. It was also noted that solid samples of 1-2 could be reacted with H2 to give cis-3-2 as the major product in a 10:1 ratio over trans-3-2. The product mixtures appeared to be kinetic in nature as no interconversion between cis and trans isomers was observed even after extended periods of heating.

Interconversion from cis-3-2 to trans-3-2 was observed when the mixture was irradiated with

254 nm light, confirming that the trans isomer is more stable. These observations lead to the proposition that, following adduct formation, hydrogenolysis of an intraring B-C bond takes place to give a 1-bora-2,4-pentadiene type intermediate (for a more detailed discussion of the mechanism, vide infra). Ensuing electrocyclic ring closure followed by 1,2-hydride migration168-

169 gives the observed cis- and trans- products.

Ar Ar Ar Ar H2 Ar Ar 1 atm H H Ar H Ar + Ar B Ar B Ar B CD2Cl2 H Ar Ar Ar Ar

Ar = C6H5 : 1-1 Ar = C6H5 : cis-3-1 (1.0) trans-3-1 (4.3) Ar = C6F5 : 1-2 Ar = C6F5 : cis-3-2 (1.0) trans-3-2 (2.1)

Scheme 28. Activation of dihydrogen by boroles 1-1 and 1-2.

58 3.2 Proposed Mechanism

The mechanism of dihydrogen activation by boroles 1-1 and 1-2 has been probed via kinetic studies, the rational synthesis of a key intermediate, and DFT studies. Scheme 29 depicts a mechanism that is consistent with the results of these studies. The first step is the reversible formation of a dihydrogen-borole adduct (I), which is faster for the more Lewis acidic perfluorinated borole 1-2. This explains the much greater rate of reaction of 1-2 with H2 compared to its unfluorinated counterpart 1-1. The H2 adduct I proved be elusive to observation by NMR spectrometry, owing primarily to the low solubility of 1-1 and 1-2 at low temperatures.

The next step is the addition of the coordinated H2 across an intra-ring B-C bond (step b) via a four-centred, two-electron transition state TS1. The resulting zwitterionic intermediate cis-II features a carbocation that is both allylic and benzylic, granting it a degree of stability through charge delocalization.71 This intermediate is not observed either, as a result of the low-energy pathways leading either directly to cis-3-1/3-2 via 1,2-hydride migration (step c) or to the ring- opened intermediate III via B-C bond cleavage (step d). Significantly, this is the only route by which trans-3-1/3-2 can form since step c leads only to cis-3-1/3-2. Since the trans isomers are the major products of the reactions, step d must be lower energy than the seemingly more direct step c, perhaps as a result of relieving the steric strain caused by the two aryl rings. Ring- opening leads to rotamers cis- and trans-III which would be in rapid exchange via rotation about the B-C bond. Each rotamer leads to the corresponding product isomer by conrotatory ring closure (step f) to form the zwitterionic cis/trans-II, followed by 1,2-hydride migration to form the observed products. Again, the pathway leading to trans isomers would likely be lower in energy as a result of the reduced steric strain in the trans intermediates.

59 Ar Ar Ar H H Ar Ar H Ar H2 b H Ar B Ar Ar B Ar Ar δ+ B Ar a δ- Ar Ar Ar I b TS1

Ar Ar Ar Ar c Ar H Ar Ar Ar H Ar Ar Ar e Ar H Ar d c H H H e H Ar B d B B f Ar hν Ar B Ar H trans-III Ar cis-III Ar Ar f d cis-II cis-3-1/3-2

Ar Ar a: H2 adduct formation Ar Ar Ar b: addition of H across B-C bond H c Ar H 2 c: 1,2-hydride migration Ar B d B Ar H Ar d: ring opening to 1-bora-2,4-pentadienes e: bond rotation c H Ar f: conrotatory ring closure trans-II trans-3-1/3-2

3.3 Experimental Elucidation of the Mechanism of H2 Activation by Boroles

The low solubility of borole 1-2 and the speed of its reaction with H2 precluded a kinetic examination by NMR spectroscopy. Fortunately, the less Lewis-acidic borole 1-1 exhibits both greater solubility and lower reactivity towards H2, allowing the reaction to be monitored for more than four half-lives over the course of 3 – 6 hours by 1H NMR spectrometry. A method similar to that used by Parkin et al.170 was employed wherein a sample in a J. Young NMR tube is placed under an atmosphere of dihydrogen and agitated, periodically recording the NMR spectra. Agitation proved to be necessary because of the slow rate of diffusion of dihydrogen into solution, so in between recording spectra the NMR tube was attached to a modified Kugelrohr distillation apparatus and inverted at a consistent rate. Typically, a J. Young NMR tube was 60 charged with a solution of 1-1 and mesitylene (internal standard) in CD2Cl2 and subjected to three freeze-pump-thaw cycles. Dry H2 was then admitted at a known temperature, from which the pressure could be estimated. A more accurate [H2] in solution was determined from the

171 signal at 4.61 ppm with the assumption that 25% of the H2 existed as para-hydrogen. It is important to note that the [H2] in solution was measured to be approximately equal to that of [1-

1]o, but the total H2 in the 2.7 mL NMR tube was in excess by at least a factor of ten. Therefore a critical assumption of this method is that the agitation of the sample replenished the dissolved

H2 fast enough that the [H2] in solution remained relatively constant. Every trial obeyed a pseudo first-order rate law, indicating that this is a valid assumption. Furthermore, repeat trials for which the pressure of H2 was ca. 1 atm gave fairly consistent values of kobs (Figure 23):

2.24(8), 2.30(8) and 2.15(8) x 10-4 M s-1.

Figure 23: Pseudo first-order plots of the repeat trials of the reaction between 1-1 ([1-1]o = 0.016 M) and H2 (ca. 1 atm) in CD2Cl2.

Figure 24: Pseudo first-order kinetic plots of the reaction of 1-1 ([1-1]o = 0.016 M) with various pressures of H2 in CD2Cl2. Inset: Isolation method plot for the determination of reaction order in [H2]

The mechanism proposed above predicts that the reaction should be first-order in both [1-

1] and [H2]. Indeed, the observed rate constant (kobs = k[H2]) changed linearly upon varying the pressure from about 1 to 4 atmospheres (or about 10 to 40 equivalents (Figure 24, inset). The slope of the plot is 1.0 ± 0.2 (95% confidence), strongly indicating that the order in [H2] is 1; a

n -1 plot of kobs vs [H2] is most linear if n = 1 (Figure 25), in which case the slope is 0.15 ± 0.04 s .

For n = 0.5 the slope is 0.61 ± 0.28 s-1, and for n = 1.5 the slope is 0.031 ± 0.015 s-1. Evidence for the first-order behaviour in [1-1] comes from the observation that every reaction profile was accurately fitted to a pseudo first-order rate law (fits to other orders were non-linear). These results are consistent with the second-order H2 adduct formation (intermediate I).

n Figure 25: Comparative plots of kobs against [H2] for n = 0.5, 1, 1.5

The mechanism predicts that H-H bond cleavage is involved in the rate-determining step and so a primary kinetic isotope effect71 should be observable. The kinetic isotope effect for the reaction of 1-1 and H2 was measured by two methods. The first simply involved taking the ratio of kobs values for the separate reactions of 1-1 with H2 and D2 (i.e. kH/kD), and yielded a small effect of 1.10(5). The second was a competition experiment that involved exposure of 1-1 to a

1:1 mixture of H2:D2, and gave a ratio of cis/trans-3-1 and cis/trans-3-1D2 equal to 1.1(1).

Because the reaction is irreversible and bimolecular, this ratio of H2 and D2 addition products is equal to the KIE. Furthermore, no H-D scrambling has been observed in these systems.110-111

This latter method was also applied to the fully fluorinated 1-2, resulting in a KIE of 1.2(1), roughly equal, within error, to its perproteo analogue. While it may seem counter-intuitive that a reaction in which H2 is split in the rate-limiting step should have such a small KIE, these values are indeed consistent with a reversible binding of H2 followed by cleavage of the H-H bond via an asynchronous transition state (TS1, Scheme 29).

Figure 26: Pseudo first-order plots of the reaction between 1-1 and H2 (red) and D2 (blue)

The activation parameters of ∆H‡ = 34(8) kJ mol-1 and ∆S‡ = -146(25) J mol-1 K-1 were derived from an Eyring plot (Figure 27) and are also consistent with a bimolecular process.

Practical limitations involving the solubility of 1-1 and the low boiling point of CD2Cl2 required that the temperature range for the Eyring plot be quite narrow (283K to 316K), though the negative value of ∆S‡ agrees with a bimolecular process. The negative value of ∆S‡ necessitates that ∆G‡ increase with increasing temperature (Figure 27, inset), changing from 76(16) to 81(16) kJ mol-1 over the experimental temperature range. It is interesting to note that despite the increase in ∆G‡, the rate constants also increased with temperature. This is explained by considering the Eyring equation itself,71

ΔG‡ k T − k = B e RT (Equation 1) h

€ where kB is the Boltzmann constant, h is the Planck constant, T is the temperature, and R is the ideal gas constant. The equation can be regarded as the product of a linear term (kBT/h) and an 64 ΔG‡ − exponential term (e RT ), both of which depend on T. The linear term must obviously increase with T, but what is less obvious is that, for the above values of ∆H‡ and ∆S‡, the exponential term also increases.€ So while it is extremely counter-intuitive, both the rate of reaction and ∆G‡ increase with higher temperatures.

Figure 27: Eyring plot for the reaction of 1-1 with H2 (ca. 1 atm) in CD2Cl2 at 283, 298, 309 and 316 K. Inset: Calculated ∆G‡ at 283, 298, 309 and 316 K.

3.3.1 Rational Synthesis of the Ring-opened Intermediate

The results of the above kinetic experiments are consistent with the second-order formation of a

H2 adduct followed by H-H bond cleavage, but they do not provide any information about the subsequent steps. In order to gain more insight into the mechanism we sought to synthesize a ring-opened intermediate such as cis- or trans-III. Prior work by Zweifel et al.168-169 has shown that attempts to generate such 1-bora-2,4-pentadienes inevitably resulted in the rapid formation

65 of 1-bora-3-cyclopentenes, analogous to products 3-1 and 3-2. As such we have only succeeded in generating III in situ.

This was accomplished by first rupturing the borole ring via the slow addition of one equivalent of phenol at 0 ºC to give the borinic ester 3-3. The π-donating phenoxy group on boron stabilizes the compound toward ring-closure to the extent that it can be isolated as a pale yellow solid in 52% yield following recrystallization from hot toluene. In the 11B NMR spectrum of 3-3 a broad signal is observed at 44.8 ppm, nearly identical to that of Ph2BOMe

(45.2 ppm).172 The 13C DEPT-Q spectrum contains the expected 19 CH signals between 120 and

140 ppm, corresponding to the 18 aromatic and 1 benzylic/allylic CH carbons and implying that every aromatic ring exhibits free rotation in solution. Unfortunately only eight of the nine quaternary carbons of 3-3 were detected; missing quaternary carbon signals are not uncommon for arylboranes owing to the quadrupolar relaxation of a neighbouring boron atom.96 However,

3-3 contains two quaternary carbons next to the boron atom, so it is difficult to explain why only one should be observed.

Ph Ph Ph Ph Ph Ph Ph Ph PhOH DIBAl-H Ph H Ph Ph Ph Ph Ph Ph Ph B Ph B 0 ˚C B H B H H Ph Ph PhO 3-3 H Ph 1 trans-III trans-3-1

Scheme 30. Rational synthesis of intermediate trans-III from 3-3.

Fortunately, we were able to obtain X-ray quality crystals of 3-3 by slow evaporation from dichloromethane, and the molecular structure is shown in Figure 28 along with selected metrical parameters. Compound 3-3 adopts a cisoid 1-bora-2,4-pentadienyl geometry, which is

66 required for the subsequent cyclization reaction.168-169 The C1-C2-C3-C4 dihedral angle of

35.47(5)º prevents efficient conjugation of the olefinic double-bonds, resulting in localized double and single bonds. This configuration also has the C3-C4 π-bond oriented towards the trigonal planar boron atom, with a non-bonding C4-B1 distance of only 2.79 Å. Finally, the short B1-O1 distance of 1.367(3) Å testifies to the extensive π-bonding in this linkage, which is critical for stabilizing this compound to ring closure. The strong π-bonding reduces the Lewis acidity at boron, raising the barrier to conrotatory boracyclopentene formation.168-169

Intermediate trans-III was ultimately generated in situ from the treatment of 3-3 with one equivalent of DiBAl-H (DiisoButylAluminum Hydride). This was implied by the observation that trans-3-1 was the only product, with its characteristic benzylic 1H NMR signal appearing at

4.85 ppm as a singlet. Moreover the addition of pyridine resulted in quantitative formation of the

67 pyridine adduct (trans-3-1py), breaking the C2 symmetry of the molecule to give two singlets at

4.20 and 4.80 ppm in the 1H NMR spectrum. This matches the spectroscopic signature of the compounds resulting from the reaction of 1-1 and H2 (Figure 29), with the notable difference that the cis-isomer is not formed from the reaction of DiBAl-H and 3-3. This could imply that only the trans isomers result from the ring-opened intermediate III, and that the cis isomers only result from cis-II. However, it could simply be that the nature of the phenoxy/hydride exchange reaction between 3-3 and DiBAl-H that selects for trans-3-1.

trans-3-1 trans-3-1•py cis-3-1•py

H2 Ph Ph cis-3-1 Ph B Ph Ph Ph Ph py H2 Ph Ph 1-1 H H H H B N Ph Ph Ph B Ph Ph Ph + + Ph Ph Ph py Ph Ph H Ph H B B H Ph H Ph DiBAl-H Ph Ph Ph Ph

Ph Ph Ph B H OPh 3-3

Figure 29: Comparison of the 1H NMR of trans-3-1 and its pyridine adduct trans-3py resulting from the reaction between 1-1 and H2 (top), and from 3-3 and DiBAl-H (bottom). Adapted with permission from J. Am. Chem. Soc. 2013 135, 941. Copyright 2013 American Chemical Society The experimental evidence for the mechanism outlined in Scheme 29 is very strong, but many of the details remain obscured due to the difficulty involved in observing the intermediates. The NMR spectra of the reaction mixtures show only starting material and products, and the low solubility of the boroles confounds low temperature experimentation. We

68 therefore turned to DFT calculations to probe the viability of the proposed mechanism on the whole and had a complete energy surface calculated for the activation of dihydrogen for both 1-1 and 1-2. The work in the following section was performed by Virve A. Karttunen and Heikki M.

Tuononen at the University of Jväskylä.

3.4 DFT Studies

A detailed examination of the proposed mechanism was carried out at the PBE1PBE/def-TZVP level of theory, including a polarizable continuum model for the treatment of methylene chloride

(solvent) effects. The attained solution-phase energies can be seen in Figure 30 for both perfluoro and perproteo boroles.

Ar H H Ar

Ar B Ar Ar

Ar H Ar 1-1 + H2 H 1-2 + H2 Ar B Ar Ar Ar Ar Ar H Ar Ar Ar Ar H B H Ar Ar Ar B Ar Ar Ar Ar Ar H B H H

cis-3-1 trans-3-1 cis-3-2 trans-3-2

Figure 30: Calculated Gibbs free energies of the activation of H2 by boroles 1-2 (blue) and 1-1 (pink). Adapted with permission from J. Am. Chem. Soc. 2013 135, 941. Copyright 2013 American Chemical Society

69 The first step on the reaction coordinate is the reversible formation of H2 adduct I (step a,

Scheme 29), which is endergonic for both boroles, but about 20 kJ mol-1 less so for the perfluorinated system. Additionally, the energy of the transition states (TS0) is nearly equal to that of the adducts, and as a result these intermediates can either release H2 or approach transition state TS1. The latter option leads to the addition of H2 across a B-C bond to give intermediates cis-II, where the π-electrons of the antiaromatic system function as an internal

Lewis base and heterolytically cleave the H-H bond. The relative energies for TSI are 74 kJ mol-1 and 61 kJ mol-1 for 1-1 and 1-2, respectively, in good agreement with the relative reaction rates. Furthermore, the experimentally determined activation energy of 78(16) kJ mol-1 is in good agreement with the computed value for the perproteo system.

Intermediates cis-II can proceed to transition states TS2 and TS3, which have very similar energies. This is particularly true for perfluorinated borole 1-2, whose TS2 -TS3 energy difference is noticeably smaller than that for borole 1-1. Seemingly, this indicates that the ratio of cis-3-1:trans-3-1 should be closer to unity than the ratio of cis-3-2:trans-3-2, the opposite of what is observed experimentally. Transition states TS2 and TS3 are also very close in energy to cis-II, implying that they are very short-lived and that their formation is essentially irreversible.

Hydride transfer from boron to carbon (step c) leads to the cis-3-1/4-2 products from TS2.

However, the long B-C bonds in cis-II (1.711 Å for 1-1 and 1.731 Å for 1-2) lend themselves to cleavage and ring-opening via TS3 (step d), leading to the cis-1-bora-2,4-pentadienyl rotamers cis-III. Rotation about the other B-C bond that was part of the ring gives trans-III through transition states TS4 with barriers of 28 and 30 kJ mol-1 for the proteo and fluoro systems, respectively. Both cis-III and trans-III adopt s-cis conformations in which the torsion angles of the dienyl moieties are 34.1˚ and 33.4˚, respectively. It is conceivable that the s-trans

70 conformers could be achieved by rotation around the C-C single bond, though they would not necessarily lie on the reaction coordinate. Furthermore, it is likely that the barrier to rotation about the C-C bond is larger than that for the B-C bond due to the greater steric crowding around the former. The following ring closure is virtually barrierless (TS5) and gives intermediates trans-II, which subsequently undergoes hydride migration (via TS6) to complete the reaction pathway with the formation of trans-3-1/3-2. As one would expect, the trans products are more stable (by ca. 20 kJ mol-1) than the cis isomers.

71 The rate-limiting step of the reaction involves H-H bond cleavage (TS1), ostensibly incongruent with the low experimental KIEs. However this can be explained by the low concentration of adducts I and the asynchronous geometry for the H-H cleavage in TS1 (Figure

31). To confirm this, the reaction profile found in Figure 30 was computed with D2 and it was found that there was almost no impact on the energies of I nor TS1 (0-2 kJ mol-1).

Figure 30 reveals a great deal of overlap in the energy profiles of the two boroles after the rate-limiting step. The overall energetics of the mechanism can be viewed as nearly independent of the borole, save for the energies of I, TS1, and the products. In each of these cases the perfluoro system is roughly 20 kJ mol-1 more favoured than the perproteo, implying that the short

F-H and F-B contacts observed in the optimized structures might be at play. By performing calculations on partially fluorinated systems, it was revealed what role these contacts play in the mechanism.

Indeed, it was found that for fluorinated 1-2, intermediate I and TS1 gain about 10 kJ mol-1 total stabilization from two short F-H contacts (2.106 – 2.391 Å). Therefore the relative speed of the reaction of 1-2 compared to that of 1-1 has its origins in not just greater Lewis acidity, but also in of the formation of van der Waals interactions that 1-1 is simply not capable of. Similarly, the lower energy of trans-3-2 relative to both trans-3-1 and cis-3-2 is partially (8 kJ mol-1) accounted for by two short (2.716 Å) F-B contacts present in its structure.

The reaction mechanism presented in Scheme 29 is strongly supported by these theoretical calculations, but this does not negate the need to consider other reaction mechanisms as well. A more comprehensive scan of the potential energy surfaces of 1-2 and 1-2 with H2 revealed that the only reactive site was to be found at and around the boron atom in both boroles.

Another transition state TS7 (Scheme 31) involving the addition of H2 across the external B-C

72 bond was found, however it was higher in energy than the TS1 of 1-1 and 1-2 by 72 and 46 kJ mol-1, respectively.164 Additionally, the reaction profile following from this transition state necessitated the breakage of the external B-C bond to give a B-H species173 and benzene/pentafluorobenzene, neither of which are experimentally observed. So while external

B-C bond hydrogenolysis is plausible, it is not competitive with the mechanism discussed above.

Ar Ar Ar Ar H H Ar H2 Ar B Ar B Ar B H + ArH Ar Ar Ar Ar Ar Ar Ar = C H : 1-1 6 5 TS7 Ar = C6F5 : 1-2

Scheme 31. Cleavage of the external B-C bond by dihydrogen

3.5 Activation of Dihydrogen by Boraindenes

With the mechanism of H2 activation by boroles 1-1 and 1-2 well understood, we set out to explore the reactivity of other boroles with this ubiquitous small molecule. Our group had previously reported the synthesis and Lewis acid properties of perfluoro-9-phenyl-9-borafluorene

1-6 (Scheme 32).87 However, it was not seen to react with dihydrogen under any conditions that it was subjected to (this work remains unpublished and was performed by Dr. Jason Dutton). We therefore turned our attention to 1-4, hoping that it would allow for reversible activation of H2;

1-4 is essentially a hybrid of a compound that reacts irreversibly with H2 and another that does not react with H2. Given that the work discussed above indicates B-C(vinyl) bonds are more prone to hydrogenolysis than B-C(aryl) bonds, the expected product of H2 activation by 1-4 would be IV.

73 F F F F C F F5C6 C6F5 F F 5 6 F F C F F F5C6 5 6 B C6F5 B B F F F C6F5 C6F5 C6F5 1-2 1-6 1-4

H2 H2 ? H2

F F5C6 F F5C6 C6F5 F F F F H H F F5C6 H F B F F5C6 C F F H 6 5 H B F C6F5 B 3-2 H F IV C6F5 C6F5

Scheme 32. Reactions of borole 1-2, borafluorene 1-6 and boraindene with 1-4.

85 At room temperature, no reaction was observed between 1-4 and H2 (ca. 1 atm). Upon heating to 125 ˚C for 20 hours a new set of 19F NME signals began to appear, but the reaction did not go to completion on further heating nor did it appear to be clean (Figure 32). The boraindene

1-4 itself is stable under these conditions without H2, so it appears that reaction product(s) of H2 and 1-4 (possibly IV) are prone to decomposition under these conditions.

19 1 Figure 32. F{ H} spectra of 1-4 in toluene-d8 (top) and of 1-4 after 20 hours under 1 atm H2 at 125˚C.

74 F F5C6 F F C F F 5 6 HCl (gas) F5C6 Cl F F C F 5 6 B CH Cl , RT H F 2 2 B F 1-4 C6F5 3-4 C6F5 + H2

- H2 Me2Si(H)Cl F C F 5 6 F F5C6 H F H B F

IV C F 6 5

Scheme 33. In situ generation of intermediate IV from chloroborane 3-4 and Me2Si(H)Cl

With the prior success of generating the 1-bora-2,4-pentadiene intermediate III through sequential reactions of borole 1-1 with H+ then H-, we reasoned that a similar approach should generate IV from boraindene 1-4. Reaction of 1-4 with one equivalent of HCl gas at room temperature gave the chloroborane 3-4 almost exclusively (Scheme 33), which could be isolated in 89% yield after recrystallization from hexanes. The 19F NMR spectrum contains a unique set

1 of thirteen signals, indicating that the C6F5 rings are freely rotating in solution. The only H resonance appears as a singlet at 6.76 ppm, consistent with the proton occupying a vinyl (as opposed to aryl) position. The broad 11B signal is at 61.5 ppm, indicating a three-coordinate boron centre. The structure of 3-4 was confirmed by X-ray diffraction analysis and the thermal ellipsoid depiction is shown in Figure 33. The environment around the boron centre is planar with a sum of angles equalling 360.0˚, and the compound adopts a cisoid configuration with respect to the H and Cl atoms in the solid state.

Figure 33. Thermal ellipsoid (50%) diagram of 3-4. Selected bond lengths (Å) and angles (1): B1–C1 1.575(5), C1–C2 1.353(5), C2–C3 1.483(5), C3–C8 1.415(5), B1–C8 1.553(6); B1–C1– C2 108.3(3), C1–C2–C3 111.1(3), C2–C3–C8 109.9(3), C3–C8–B1 106.8(3), C8–B1–C1 103.5(3).

Treatment of a solution of 3-4 in CH2Cl2 with 1.6 equivalents of Me2Si(H)Cl at room temperature results in a gradual colour change from pale yellow to orange/red. After 24 hours the only product observed in the 19F NMR spectrum is 1-4, while the 1H spectrum shows resonances corresponding to H2 and Me2SiCl2, as well as unreacted Me2Si(H)Cl (Figure 34).

Observation of the reaction mixture at approximately 50% conversion (after 2.5 hours) reveals that the only major species are 1-4 and 3-4 (Figure 35). This indicates that the hydride exchange to form IV is rate-limiting, followed by a fast release of H2 to form 1-4. It is also apparent that

IV is less energetically favourable than H2 and 1-4, with entropy providing a sufficient driving force to form an anti-aromatic compound

1 Figure 34. H NMR spectrum (tol-d8) of the reaction mixture of 3-4 and Me2Si(H)Cl after 24 hrs

77 3.6 The Boraindene-Mediated Hydrogenation of Cyclohexene

Having confirmed the viability of borane intermediate IV, we surmised that it might be trapped

47-49 via hydroboration of an olefin; elimination of an alkane instead of H2 from such an alkylborane would complete a catalytic cycle (Scheme 34). Indeed, treatment of a solution of cyclohexene and 3-4 with Me2Si(H)Cl led to the relatively clean formation of the hydroboration product 3-5, which was isolated in 69% yield. NMR spectroscopy and elemental analysis were consistent with the structure of 3-5, and the connectivity of the molecule is supported by X-ray crystallography, although the crystallographic data is not of sufficient quality to discuss bond lengths (Figure 36).

F F5C6 F F C F F 5 6 HCl (gas) F5C6 Cl F F C F 5 6 B CH Cl , RT H F 2 2 B F 1-4 C6F5 3-4 Me2Si(H)Cl C6F5

- Me2Si(H)Cl + H2 - H2 H H 140˚C

F C 5 6 F F C F F C F 5 6 5 6 F - F C C6F5 F 5 6 H H F B H F B F + 3-5 H IV C F 6 5

Scheme 34. Potential catalytic cycle for the hydrogenation of cyclohexene by boraindene 1-4.

Alkane elimination was then forced by heating a solution of 3-5 to 140˚C for several hours. Indeed, 1H NMR analysis confirmed the formation of cyclohexane, though only as a

78 minor product among many aliphatic resonances (Figure 37). Cyclohexene also formed in approximately six-fold excess over cyclohexane, indicating that retrohydroboration47 is favoured; retrohydroboration would generate IV, which in turn would decompose to H2 and boraindene 1-4

1 (Scheme 34). In fact, H2 is also observed in the H NMR, and 1-4 appears as a major species in the (rather complex) 19F NMR spectrum.

Figure 36. Thermal ellipsoid (50%) diagram of 3-5.

1 Figure 37: H NMR spectrum (C6D6) of 3-5 after heating at 140 ˚C for 2.5 hours.

79 3.6.1 The reaction of 1-4 and cyclohexene

The complexity of the 19F NMR spectrum prompted an investigation of other possible side-reactions in this system. In particular, we hypothesized that reaction between boraindene 1-

4 and cyclohexene via 1,1-carboboration3 pathways might be operative. Previous work in our group112 has shown that 1-2 can react with unsaturated hydrocarbons (alkynes) to yield a mixture of a boracyclohexadiene and heptaarylborepines (the reaction with diphenylacetylene is shown in

Scheme 35 for illustration).

F5C6 C6F5 F5C6 C6F5 Ph F C C F F C C F F5C6 5 6 6 5 5 6 C B 6 5 Ph Ph + F C Ph B 5 6 B C6F5 C C6F5 F5C6 Ph 25˚C, CH2Cl2 Ph C6F5 C6F5 1-4 boracyclohexadiene heptaarylborepin (major product) (+ others)

Scheme 35. Reaction of 1-4 with diphenylacetylene

At room temperature, a solution of 1-4 and excess cyclohexene in CH2Cl2 gradually proceeds from orange-red to pale yellow over the course of roughly four hours. A new set of

19 resonances in the F NMR spectrum reveal a single new product in which all three C6F5 groups can freely rotate. The 1H NMR spectrum shows only aliphatic signals, and the 13C (DEPT-Q) spectrum indicates that the cyclohexyl moiety contains three chemically unique -CH2- units. X- ray analysis confirmed that the new product was the spirocyclic boranaphthyl compound 3-6

(Scheme 36 and Figure 38). The tricoordinate boron environment is planar with a sum of angles equalling 359.6˚, but the boracyclohexadienyl ring is significantly bent; the C7-C1-B1-C14

80 torsion angle is -43.73˚. The C6F5 ring on boron is disordered over two positions, though the solution to the structure is adequate for the purposes of discussing bond lengths and angles.

F C F 5 6 F F F5C6 RT F5C6 F + F C F 5 6 B B F CH Cl F 2 2 F C F 6 5 C6F5 1-4 3-6

Scheme 36. Reaction of cyclohexene with 1-4 to form 3-6

Figure 38. Thermal ellipsoid (50%) diagram of 3-6 with fluorine and hydrogen atoms excluded for clarity. Selected bond lengths (Å) , angles (˚) and torsion angles (˚): C1-B1 1.578(3) C14-B1 1.554(3) C28A-B1 1.583(3); C14-B1-C1 115.79(18), C14-B1-C28A 121.14(17), C1-B1-C28A 122.64(18); C7-C1-B1-C14 -43.73.

Compound 3-6 is likely formed via a 1,1-carboboration3, 41-42, 174 mechanism, which is well-known to occur between fluoroarylboranes of the type (C6F5)2BR (R = alkyl, aryl) and alkynes. To the best of our knowledge, this is the first example of a 1,1-carboboration of an olefin by a fluoroarylborane. In the present case, the first step of the mechanism is the

81 electrophilic attack of 1-4 on cyclohexene, followed by a 1,2-hydride shift of one of the

(formerly) olefinic hydrogen atoms onto the formally cationic carbon (Scheme 37). Subsequent ring expansion would give 3-6. Terminal alkynes are also known to undergo 1,1-carboboration42

(via a 1,2-hydride shift) under mild conditions, so it is unsurprising that cyclohexene should react this way.

F F F F F C F5C6 5 6 F F5C6 F B F C H F 5 6 B C F electrophilic H F 6 5 attack 1-4 C6F5 H H

1,2-hydride shift

F F F C F5C6 F 5 6 F C F ring 5 6 expansion F F5C6 B H B F F F C6F5 H C6F5 H 3-6 H

Scheme 37. Proposed mechanism for the formation of 3-6 from 1-4 and cyclohexene

3.6.2 Summary of the thermal decomposition of 3-5

The spirocyclic boranaphthyl compound 3-6 was confirmed as the other major species

(along with 1-4) seen upon heating the hydroboration product 3-5 (Figure 39). Presumably this forms after retrohydroboration releases cyclohexene and 1-4 (via decomposition of IV), which

82 then react to form 3-6. At 140˚C in the presence of excess cyclohexene, 3-6 decomposes into other products, further complicating the reaction mixture.

F5C6 F4 F5C6 F5C6 H B

3-5 H

F5C6 F C F5C6 5 6 F C Δ 5 6 F H B 4 H F5C6 B + H2 + + 3-5 H 1-4 H C6F5

F C F5C6 5 6 F F4 Δ F5C6 F F C + decomposition 5 6 B + B F products 1-4 C F 6 5 3-6 F C6F5

F5C6 F4 F5C6 B 1-4 C6F5

The mechanism of cyclohexane formation is therefore obscured. In addition to the possibility of cyclohexane elimination from borane 3-5 to reform boraindene 1-4 and closing a catalytic cycle (Scheme 34), one must consider the possibility of B-C(alkyl) bond of 3-5

57 58 undergoing σ-bond metathesis with H2. Recent work by Wang et al. shows that Piers’

47-49 borane (HB(C6F5)2) can act as a catalyst for the hydrogenation of olefins, so it is possible that

IV would in fact be the active catalyst (Scheme 38). Furthermore, it is possible that the B-

83 C(alkyl) bond of 3-6 could under go σ-bond metathesis to form a hydridoborane that could also act as a catalyst. Heating 3-5 under ca. 5 atm D2 resulted in the formation of trace cyclohexane-

H12 among a mixture of deuterated cyclohexanes, indicating that indeed the concomitant formation of cyclohexane-H12 and boraindene 1-4 from 3-5 is operative, but not significant.

F C F F 5 6 F F C F H F5C6 5 6 2 H F F C F H 5 6 B B F F 1-4 C6F5 C6F5 IV

H F5C6 F5C6

B H B

R R F5C6 F F5C6 F F5C6 F F5C6 F H2 B F H H F σ-bond F Δ B metathesis H2 C F F 6 5 H H C F 3-6 6 5

Scheme 38. Alternate mechanisms for the 1-4-mediated hydrogenation of cyclohexene

3.6.3 Catalytic Hydrogenation Experiments

Despite the uncertainty of the precise mechanism of cyclohexene hydrogenation, we sought to assess the catalytic activity of this system. With 10 or 20% loadings of 1-4, roughly 4-5 turnovers were observed at 140˚C in C6D6 under ca. 5 atm H2. The lower catalyst loading experiment showed a cyclohexane yield (by NMR spectroscopy) of 54%, with approximately

30% of the cyclohexene unreacted (after 48 hours). At higher catalyst loading, complete consumption of cyclohexene was observed after 72 hours, though the yield of cyclohexane is

84 only about 70%. The reaction between 1-4 and cyclohexene accounts for most of the missing mass balance. However, the major species in the 19F NMR spectrum of the hydrogenation reaction mixture is neither the hydroboration product 3-5, the spirocyclic boranaphthylene 3-6, nor boraindene 1-4.

In a separate experiment, a solution of cyclohexene with 10% 1-4 was heated for 90 min at 140˚C to quickly form 3-6 and some of the decomposition products. This mixture was then subjected to three freeze-pump-thaw cycles and subsequently ~5 atm H2. After heating at 140˚C for 48 hours, the conversion to cyclohexane was about 32%, suggesting that 3-6 is a potential catalyst or pre-catalyst for olefin hydrogenation as well. So while boraindene 1-4 can indeed mediate the metal-free hydrogenation of cyclohexene, it is unclear what the active catalyst(s) is(are). We turned to DFT calculations (performed by Virve A. Karttunen and Heikki M.

Tuononen) to help ascertain the energetics of the originally expected pathway outlined in

Scheme 34.

3.7 DFT Studies on the Activation of Hydrogen and Hydrogenation of Olefins by 1-4

The calculated reaction coordinate for H2 and boraindene 1-4 is reminiscent of the one calculated for H2 and boroles 1-1/1-2 (vide supra). Following formation of a H2-boraindene adduct V

(Figure 40), H2 is heterolytically split across the vinyl B-C bond to give the zwitterionic intermediate VI. This is the rate-limiting step with an activation barrier of 90 kJ mol-1, somewhat higher than for the analogous reaction of boroles 1-1 and 1-2 with H2 (74 and 61 kJ mol-1, respectively). The product IV can adopt either cis or trans configurations, which are higher in energy than the reactants by 25 and 14 kJ mol-1. These results are consistent with the experimental observations; the ΔG of 14 kJ mol-1 means that the equilibrium constant would vary 85 from 1.8 x 10-3 at 0˚C to 1.5 x 10-2 at 140˚C. While these values might be different in a physical system, they provide a semi-quantitative explanation as to why IV is not observed by direct

-1 reaction of 1-4 with H2. The activation barrier for the reverse reaction is 76 kJ mol , which should render the observation of IV at room temperature feasible. However, IV is generated from the chloroborane 3-4 and Me2Si(H)Cl, a process which implicitly has a higher activation barrier.

ΔG kJ/mol 100 TS9 (82) (90) TS10 TS13 80 (75) transition states (79) TS12 for hydroboration VI H 4 (78) (62) (61) C 2 TS8 + 60 F TS11 V Ar H F4 TS15 H (56) 4 (53) H ArF B 2 40 C ArFH H F4 ArF + F Ar B VI (25) 20 cis-IV ArF V (14) trans-IV 0 ArF ArF F4 F4 1-4 + H2 F ArF H Ar ArF TS14 H (-19) -20 H B B ArF H -40 cis-IV trans-IV

hydrogen addition/ring opening (-58) -60 cis manifold trans-VII (-61) trans manifold cis-VII ArF ArF alkane elimination/ring closing F4 F4 ArF ArF ArF Et ≈ H ≈ B H B -116 (-116) Et ArF 1-4 + C2H6 trans-VII cis-VII

Figure 40. Calculated Gibbs free energies (kJ mol-1 ; PBE1PBE/TZVP) for the reaction of 1-4 with H2 and the subsequent addition of ethylene and elimination of ethane.

Ethylene was used in the model DFT system for computational simplicity.

Hydroboration of ethylene by IV proceeds with a low activation barrier of 64 kJ mol-1,, and the product cis-VII is thermodynamically favoured by 75 kJ mol-1. Ethane elimination to re-form boraindene 1-4 proceeds with a large activation barrier of 114 kJ mol-1 and a thermodynamic

86 driving force of 55 kJ mol-1. Here the computational results differ from the experimental observation that retrohydroboration is favoured over alkane elimination; the calculated barrier for retrohydroboration is 139 kJ mol-1, 25 kJ mol-1 higher than the barrier for alkane elimination.

This is likely an artefact of the choice of ethylene for this system. Nonetheless, these computational results indicate that the 1-4 – catalyzed hydrogenation of olefins is at least energetically viable.

3.8 Conclusions

The rapid reaction of dihydrogen with antiaromatic boroles 1-1 and 1-2 demonstrates that strong, main-group Lewis acids can not only bind H2 but activate it as well, even in the absence of an external base. These reactions show that Lewis acid-H2 adducts, despite their transient nature, can proceed to further reactivity other than the release of H2 if a sufficient thermodynamic driving force is present. There is very convincing experimental and computational evidence supporting the mechanism outlined in Scheme 29, including the rational synthesis of intermediate III and good agreement between calculated and experimental activation barriers.

When H2 activation was extended to the perfluoroaryl boraindene 1-4 it was found that the forward reaction is not energetically favourable, but both computational and experimental evidence support the spontaneous reaction of IV to form H2 and 1-4. While more direct empirical evidence of the forward reaction is necessary, the results presented herein show great promise for the tuning of borole reactivity through modification of their organic frameworks.

Furthermore, the sequential reaction of boroles with H+ and H- has proven to be an effective way to mimic their reactions with H2.

87 Finally, boraindene 1-4 was shown to mediate the hydrogenation of cyclohexene. DFT calculations indicate that 1-4 can act as a catalyst for the hydrogenation of ethylene, but experimental results indicate that the role of 1-4 is primarily that of a pre-catalyst, with the active catalyst being undetermined as of yet. Boraindene 1-4 also reacts with cyclohexene to form 3-6, which in turn can mediate the hydrogenation of cyclohexene as well.

Chapter Four: The Activation of Triethylsilane by Perfluoro-1,2,3-triphenyl-1-boraindene

4.1 Introduction

Hydrosilation (also called hydrosilylation) is the addition of an Si-H bond to a substrate, a transformation that has proven to be of enormous importance to both academic and industrial chemistry.175-177 Substrates include unsaturated functions such as C=O,176, 178 C=N,176, 179-180

C=S,181 C=C176, 182 and C≡C bonds, and the addition nearly always proceeds in a 1,2-fashion such that the silicon atom ends up bonded to the more electronegative atom (in the cases of C=O,

C=N and C=S) or the less substituted atom (i.e. an anti-Markovnikov addition to C=C or C≡C bonds) (Scheme 39); 1,4-additions are known to occur in conjugated systems such as enones.183

Hydrosilation provides organic chemists with a convenient way to produce “protected” alcohols,

R2(H)C-O-SiR3’ functions which are typically stable to base, oxidation, and reduction, and may later be hydrolyzed to unprotected alcohols.184 This also provides a means by which C=O and

C=N bonds may be ultimately reduced to HC-OH and HC-NH functions instead of by direct hydrogenation.185 The hydrosilation of C=C bonds is used in the synthesis of various silicones,186 a ubiquitous class of materials in which the silyl function plays a key role.

Scheme 39. General hydrosilation of unsaturated organic compounds

89 Hydrosilation is typically carried out by transition metal catalysts, with platinum among the most common due to its importance in the industrial production of silicones.176-177, 186 The high cost of platinum has prompted the search for cheaper and less toxic metals, such as palladium,187 ruthenium,188-190 cobalt191 and molybdenum.192 With the diversity of organometallic complexes used for a process comes a diversity of mechanisms, and hydrosilation is no exception. Most mechanisms involve the activation of the Si-H bond in some fashion, typically through oxidative addition (e.g. the Chalk-Harrod mechanism)191, 193 or σ-bond metathesis.187 Recent work in the Tilley group has shown that metal-silylene complexes are capable of inserting substrates into the activated Si-H bond in both a 1,1-194 and a 1,2-fashion,188,

190, 195-198 but only the latter is involved in known hydrosilation mechanisms. Another less common mode of Si-H activation is for the organometallic catalyst to act as a simple Lewis acid, forming a σ-complex (which may be regarded as a Lewis acid/base adduct) with the weakly basic Si-H bond and activating it towards nucleophilic attack.189

This last mechanism bares a strong resemblance to the hydrosilations of carbonyl

(C=O)178 and imine (C=N)179 functions. catalyzed by the strong Lewis acid

157 199 tris(pentafluorophenyl) borane B(C6F5)3. The first step of the mechanism is the formation of a borane-silane adduct (Scheme 40), despite the formation of borane-carbonyl200 and borane- imine201 adducts being thermodynamically more favourable. The borane-silane adduct then

202 undergoes nucleophilic attack by the substrate via an SN2 mechanism to generate an ion pair.

Following this the hydrido borate delivers a hydride to the organic cation, releasing the hydrosilated product and regenerating the borane catalyst.

Scheme 40. Mechanism for the B(C6F5)3-catalyzed hydrosilation of unsaturated organic compounds

Since the initial reports of this chemistry, much experimental and computational203 support for the above mechanism has been generated. Activation of the carbonyl groups by

B(C6F5)3 was ruled out by the Piers group, who showed that more basic carbonyls are hydrosilated slower than less basic ones.178, 199 Oestreich and colleagues have used chiral silanes to elegantly demonstrate the Walden inversion at silicon via the borane-silane adduct, which

202 could only result from an SN2 mechanism. In some cases the ion pair intermediate has been observed spectroscopically,179, 204 and labelling studies indicate that hydride delivery by the

- 199 hydridoborate [HB(C6F5)3] is favoured over delivery by silane.

The borane-silane adduct has not been conclusively observed, though there are several reactions beyond hydrosilation that invoke it. For example, it has also been shown that B(C6F5)3 slowly reacts with Et3SiH to give bis(pentafluorophenyl) borane, HB(C6F5)2 , and Et3SiC6F5, a reaction in which a borane-silane adduct is implied.57 Furthermore, H/D scrambling has been

199 observed between different silanes in the presence of B(C6F5)3. Low-temperature

91 spectroscopic studies have failed to convincingly detect a borane-silane adduct, indicating that such a species is thermodynamically disfavoured. Indeed, DFT calculations performed by

Sakata and Fujimoto reveal that the trimethyl silane–borane adduct Me3SiH-B(C6F5)3 is disfavoured by about 3.2 kcal/mol, consistent with its apparently unobservable nature.203

In a recent report Berke et al. claim to have observed the 29Si NMR resonance of the

205 triethylsilane (Et3SiH) adduct at -40˚C (-9.8 ppm in toluene-d8, 1:1 Et3SiH:B(C6F5)3). This report also includes a room-temperature spectrum of a similar reaction mixture with an unassigned signal at 9.3 ppm, presumably belonging to the adduct as well. However, this would

29 contradict the earlier observation by Piers et al. which saw the Si resonance at 1.2 ppm (C6D6 as solvent) for a 1:1 mixture of Et3SiH:B(C6F5)3. Further investigation of the methods revealed that B(C6F5)3 was used as received in the Berke report; commercial samples of B(C6F5)3 typically contain non-negligible amounts of water and require rigorous drying before use. In the

206-207 presence of water and Et3SiH, B(C6F5)3 catalyzes the dehydrogenative silation of water to form (Et3Si)2O. We carried out this reaction to generate a sample of (Et3Si)2O and found that the

29Si resonance does indeed occur at 9.3 ppm at room temperature. Therefore the claim that the

Et3SiH->B(C6F5)3 adduct has been observed is almost certainly false, and these species remain unobserved.

In order to shift the equilibrium towards the formation of a borane-silane adduct, one must either use a more Lewis basic silane or a more Lewis acidic borane. The degree to which the Lewis basicity of Si-H bonds may be increased is rather limited,208 but there are numerous ways to increase the Lewis acidity of boranes. Anti-aromatic boroles118 such as 1-183 and 1-284

85, 110-111 have proven to be extremely Lewis acidic, as demonstrated by their ability to activate H2 and to bind carbon monoxide (CO).98 A more recent report has shown that borole 1-1 activates

92 99 110 the Si-H bond of Et3SiH (Scheme 41) in a manner similar to the activation of H2, presumably by a similar mechanism.111 However, the low solubilities of 1-1 and 1-2 preclude any low- temperature spectroscopic studies aimed at detecting their silane adducts.

Ph Ph Ph Ph Ph Ph Et3SiH Ph SiEt 60 ˚C H SiEt Ph Ph 3 3 B H B Ph Ph B Ph Ph Ph Ph "transoid" "cisoid" 1-1 product product

99 Scheme 41. Activation of Et3SiH by borole 1-1

In the previous chapters we established the extreme Lewis acidity of perfluoro-1,2,3- triphenyl-1-boraindene 1-4, which is also very soluble in organic solvents. Here we exploit these favourable properties in order to demonstrate the viability of borane-silane adducts, as well as explore the potential of 1-4 as a hydrosilation catalyst for olefins.

4.2 Solution-phase behaviour of the Silane-Boraindene equilibrium

The synthesis, properties, and reactivity of boraindene 1-4 are discussed in Chapters 2 and 3.

The characteristic red colour of 1-4 is retained in solution, though most of its reaction products

(including Lewis-base adducts) are colourless to pale-yellow in solution. Thus, its reactions

(ring-opening, ring expansion, or Lewis adduct formation) are visible to the naked eye by the loss of red colour.

A solution of 1-4 in toluene-d8 with 1-2 equivalents of triethylsilane (Et3SiH) exhibits no discernable colour change, while the 1H and 19F NMR spectra are only slightly perturbed. The

93 Si-H resonance experiences a slight upfield shift from 3.83 to 3.71 ppm while retaining its septet coupling pattern, and the thirteen 19F resonances move only slightly upfield. These solutions are stable for up to five days at room temperature, after which only slight (< 5%) decomposition can be detected by 19F NMR. These results suggest that irreversible ring-opening reaction (such as the one undergone by borole 1-1 and Et3SiH) does not take place to a significant extent under these conditions. A more striking indication of a reversible adduct forming reaction was observed on increasing the concentration of Et3SiH to roughly ten times that of 1-4. At room temperature the solution remains red, but turns distinctly yellow upon cooling to -78˚C.

Warming the solution back to room temperature results in a return of the red colour, and this process can repeated through several cycles. This qualitative evidence of a reversible adduct formation (Scheme 42) prompted a thorough spectroscopic and structural study with a view to determine the thermodynamic parameters of the equilibrium and the structural properties of 4-1.

Ph Ph Ph Ph Ph Ph Et3SiH Ph SiEt 60 ˚C H SiEt Ph Ph 3 3 B H B Ph Ph B Ph Ph Ph Ph "transoid" "cisoid" 1-1 product product

Scheme 42. Formation of the boraindne-silane adduct 4-1.

4.2.1 Thermodynamics of the Boraindene-Silane equilibrium

19 The aforementioned thermal colour changes of 1-4/Et3SiH solutions are echoed in their F NMR spectra: cooling the solution results in an upfield shift of most of the 19F signals as adduct formation becomes more favourable (Figure 41, right)). This phenomenon is also observed upon

94 titrating a solution of 1-4 with Et3SiH (0.37 – 17 equivalents). In both cases, the signal resulting from the fluorine atom ortho to boron on the boraindenyl moiety moves significantly more than the others (marked with a red dot in Figure 41), and as such was chosen to quantify the equilibrium constant (Ka) at various temperatures. Thus far we have been unable to directly observe 4-1 by NMR because the forward and reverse reaction rates are faster than the NMR timescale at all accessible temperatures. The spectra therefore reflect an average of the signals resulting from 1-4 and 4-1, which can in turn be used to measure the equilibrium constant according to Equation 2:

Δδ K [Et SiH] Equation 2 Δδ = tot a 3 1+Ka[Et 3SiH]

€ The above equation is referred to as a binding isotherm71 and was originally derived as a description of a reversible host-guest interaction, where a “host” molecule at a fixed concentration interacts with a guest molecule (in this case Et3SiH) of varying concentrations, resulting in measurable changes in the NMR spectra of the system. In this scenario Δδ is a measurable quantity from the NMR spectra, representing the difference between the chemical shift of 1-4 at equilibrium (δeq) and uncoordinated 1-4 (δ1-4). Similarly, Δδtot represents the total change in chemical shift of 1-4 on adduct formation, equal to the difference between the chemical shift of 4-1 (δ4-1, which is not observed) and δ1-4. The equilibrium constant is represented by Ka, and [Et3SiH] is the concentration of triethylsilane at equilibrium. This latter value can be calculated using the quadratic expression:

2 Equation 3 Ka[Et3SiH] + (Ka[1-4]o-Ka[Et3SiH]o+1)[Et3SiH] – [Et3SiH]o = 0 95

The measured, pre-equilibrium concentrations of 1-4 and triethylsilane are represented by [1-4]o and [Et3SiH]o, respectively.

19 Figure 41. F NMR spectra of a solution (tol-d8) of 1-4 (0.026 M) with varying [Et3SiH] at 273 K (left) and at varying temperature with a fixed [Et3SiH] = 0.051 M (right)

Taken together, Equation 2 and Equation 3 allow for the determination of Ka and Δδtot through non-linear least squares regression analysis: the sum of the squares of the differences between measured and calculated values of Δδ were minimized by varying the values of Ka and

Δδtot with Solver for Microsoft Excel 2008 for Mac. Errors in these values were estimated through use of the solvstat.exe macro in Microsoft Excel 2004 for Windows.209 This allowed for best-fit curves to be calculated and compared to the measured values of Δδ; the plots of Δδ against [Et3SiH]o and their best-fit curves at six different temperatures are displayed in Figure

42.

19 Figure 42. Scatter plots of the Δδ in the F NMR spectra of 1-4 on titrating with Et3SiH at various temperatures and their fitted curves from the binding isotherm

There are several variables that affect this system and must be taken into consideration.

Firstly, [Et3SiH]o was varied by simply adding different amounts to a set volume of stock solution containing 1-4, C6F6, and mesitylene, so dilution due to addition of Et3SiH affects the concentrations of all species in the solution. Mesitylene was included as an internal standard to verify that the correct amounts of Et3SiH were added, but for the most part the volume of Et3SiH was not considered to affect the total volume of the system. This assumption was aided by keeping the added volumes of Et3SiH small (1 – 45 µL) relative to the volume of stock solution

(600 µL) for nearly all samples (see Chapter 6 for further details). The thermal dependence of toluene’s density also necessitated that the concentrations be adjusted at different temperatures.

The density at various temperatures was estimated using the following formula:

97 ρ0 ρ1 = Equation 4 1+ β(t1 − t0 )

€ where ρ1 is the density of toluene-d8 at temperature t1, ρ0 is the density at t0 = 298 K (0.943

-1 210 g/mL), and β is the volumetric thermal coefficient of expansion for toluene-h8 (0.00108 K ).

The value of β is not known for toluene-d8, so it was assumed that the value for toluene-h8 would provide a reasonable approximation. Finally, the values of Δδ depend not only on the equilibrium, but also on the temperature and dielectric constant of the system, the latter of which changes with different concentrations of Et3SiH. Hexafluorobenzene was used as an internal standard with a fixed δ = -162.97 ppm so that Δδ would only reflect the position of the equilibrium and not the thermal nor dielectric variables.

Table 4: Total chemical shifts (Δδtot) and equilibrium constants (Ka) from the NMR titration of boraindene 1-4 with Et3SiH. T (K) 300 275 259 243 227 211 195

Ka 1.13(4) 2.7(2) 6.2(4) 15(1) 40(2) 141(17) 950(730)

Δδtot (ppm) -10.4(2) -12.4(5) -12.8(3) -13.2(2) -13.6(1) -13.7(2) -13.8(4)

The Δδtot term was found to decrease from -10.4(2) ppm at 300 K to -13.7(2) ppm at 211

K, indicating that the chemical shifts of 4-1 are appreciably (but not significantly) dependant on temperature; the measured δ4-1 changes from -126.2 to -129.5 ppm over this temperature range.

The equilibrium constant Ka increases from 1.13(4) at 300 K to 141(18) at 211 K, providing a quantitative description of how adduct formation becomes more favourable at lower temperature.

The error in Ka (730) at 195 K is nearly the same as the value of Ka itself (950), owing to the broadness of the 19F resonances at this temperature, so it was discounted from further analysis.

98 o With Ka values at six different temperature in hand, the standard enthalpy (ΔH ) and entropy

(ΔSo) could be determined through a Van’t Hoff analysis71 of the form:

ΔH o Equation 5 −RlnK = − ΔS o a T

In the above equation, R is the ideal gas constant (8.3144621 x 10-3 kJ mol-1 K-1),211 and T is the

€ -1 o temperature. A plot of –RlnKa against T therefore gives a line with slope equal to ΔH and an intercept equal to -ΔSo (Figure 43). This yields thermodynamic parameters of ΔHo = -29.7(3) kJ

-1 o -1 -1 mol and ΔS = 100(1) J mol K for the equilibrium. The enthalpy of Et3SiH association with

203, 212 1-4 is roughly twice that calculated for the association with B(C6F5)3, but is still somewhat weak. The unfavourable entropic term renders the equilibrium nearly thermoneutral at room temperature (Figure 43, inset), but at lower temperatures this term contributes less to the overall

ΔGo and thus adduct formation becomes more favourable.

o -1 Figure 43. Van’t Hoff plot for the 1-4/Et3SiH adduct equilibrium with ΔH = -29.7(3) kJ mol , ΔSo = 100(1) J mol-1 K-1, and R2 = 0.9995.

Knowledge of the Δδtot allowed for the determination of an equilibrium isotope effect

(EIE) based on the assumption that Δδtot should be the same whether Et3SiH or Et3SiD are used.

By measuring the Δδ on addition of Et3SiD, we were able to determine the equilibrium constant

Ka-D according to Equation 2 (replacing Et3SiH with Et3SiD). The average of four measurements with 0.35, 3.8, 7.6 and 12 equivalents of Et3SiD gave a Ka-D = 1.125(5), and thus an EIE = Ka/Ka-

D = 1.00(4). This indicates that the difference in the Si-H and Si-D bonding energies does not have a significant impact on the overall ΔG˚ of adduct formation.

4.2.2 Structural Characterization of the Boraindene-Silane Adduct 4-1

The adduct 4-1 is depicted as possessing a three-centre two-electron bonding interaction between boron, hydrogen, and silicon (referred here to as the Si-H-B bond), consistent with

203, 212 computed structures for silane adducts of B(C6F5)3. Presumably this originates from an overlap of the HOMO of the silane (the σSiH bond) and the LUMO of the borane (the empty p orbital on boron). This bonding mode also supported by variable temperature 1H NMR spectra, which show a significant upfield shift in the silane hydrogen of over 1 ppm upon cooling a solution from 298 K to 213 K (Figure 44). It is probable that the upfield shift results from increased magnetic shielding from the anti-aromatic boraindene, and the magnitude of the shift indicates a significant change in the environment of the Si-H nucleus. More convincingly, the

1 Si-H coupling constant ( JSiH) decreases from 177 Hz for free Et3SiH to about 107 Hz at 213 K in the presence of a slight excess of 1-4. This is expected as the Si-H bond weakens upon interacting with the Lewis acidic boron centre.

100

1 Figure 44. H NMR spectra of a solution of 1-4 (0.065 M) and Et3SiH (0.052 M) in tol-d8 at variable temperatures (right), overlayed Et3Si-H resonances referenced to the chemical shift of 1 free Et3SiH to highlight decreasing JSiH (centre) A weakening Si-H bond as a result of adduct formation would also result in a decreased

Si-H stretching frequency. Solid samples of 4-1 were obtained by cooling a solution of 1-4 in neat Et3SiH (which, incidentally, is pale orange at room temperature) to -30˚C. The solid phase of 4-1 is colourless and appears to be stable at -30˚C for at least several days. At room temperature the solid slowly turns orange over the course of several days, presumably due to the evaporation of Et3SiH. When dissolved in any solvent, an orange-to-red solution is obtained and the major species are free 1-4 and Et3SiH. The IR spectrum (KBr pellet) of the solid displays a broad signal at 1918 cm-1 (Figure 45), which compares well to the Si-H-Si stretching frequency

+ -1 213 of the [Et3Si2(µ-H)] cation reported by Reed et al (1900 cm ) , though less well to the Si-H-B stretching frequency of the 3-bora-4-methylene-homoadamantanes (Scheme 43) reported by

Wrackmeyer et al. (1849 cm-1).214 This observation, combined with the absence of the Si-H

101 -1 -1 stretching frequency of free Et3SiH (2103 cm ), prompted us to assign the band at 1918 cm to the Si-H-B stretch of 4-1. The broadness of the signal likely originates from a number of energetically inequivalent Si-H-B bonding modes (i.e. slightly different Si-H-B bonding angles) in the amorphous solid state. Further confirmation of the Si-H-B assignment was obtained from a sample of 4-1D (prepared from Et3SiD), which is apparently missing the Si-D-B band in its IR spectrum; the harmonic oscillator model would predict that the signal moves to ca. 1400 cm-1, but this region of the spectrum is obscured by overlapping signals.

Scheme 43. Wrackmeyer B-H-Si compound214

Figure 45. Infrared spectra (KBr pellet) of Et3SiH (top left), 1-4 (top right), 4-1 (bottom left) and 4-1D (bottom right). Baselines were corrected manually.

102

The relative ease with which amorphous solid samples of adduct 4-1 could be obtained encouraged us to attempt the growth of X-ray quality crystals. This was accomplished by layering a saturated solution of boraindene 1-4 in toluene with neat Et3SiH at -30 ˚C. After several days obtained crystals that were used to determine the structure of 4-1, which is shown in

Figure 46. The structure clearly shows that the silane does bind to the boraindene via a somewhat bent (157˚) Si-H-B interaction. This is, to the best of our knowledge, the first crystallographic characterization of an intermolecular three-centre, two-electron Si-H-B bonding interaction; Wrackmeyer and coworkers were able to crystallographically characterize the intermolecular Si-H-B bond of one of their 3-bora-4-methylene-homoadamantanes (Scheme

43).214 The Si-H bond of 4-1 is 1.51(2) Å, slightly longer than a typical Si-H bond (1.480(5)

Å);215 the B-H distance is 1.46(2) Å, significantly longer than a typical B-H single bond (1.21(2)

103 Å), but close to the bridging B-H-B bond length of 1.39(2), and also well within the sum of the van der Waals radii (3.0 Å).216 As expected the environment at boron is significantly pyramidalized with a sum of C-B-C bond angles equalling 344.3(2)˚.

In addition to the primary Si-H-B interaction, there are several short contacts that could contribute to the stability of 4-1 (Figure 46). The six C-F contacts can indicate stabilization via

C-F or C-H••F interactions (we could not reliably measure the F-H contacts). Four of these contacts are close to the sum of the carbon and fluorine van der Waals radii (3.2 Å), while the longest two are still less that 4 Å. Additionally, there are three short Si-F contacts, the shortest

(3.391(3) Å) being less than the sum of the van der Waals radii (3.6 Å). These types of short

203 contacts are also present in the calculated Me3SiH-B(C6F5)3 adduct, so it is likely that the primary driving force for the formation of 4-1 is the extreme Lewis acidity of the boron centre.

4.3 Reactions of the Silane-Boraindene Adduct

The above results are the first direct evidence for the predicted borane activation of silane towards the hydrosilation of unsaturated functions via a frustrated Lewis-pair – type mechanism.

To establish that the adduct 4-1 reacts in a manner consistent with the mechanism depicted in

Scheme 40, we investigated its reactivity towards the chloride ion and examined the ability of 1-

4 to act as a catalyst for the hydrosilation of olefins.

4.3.1 Reactions of the Boraindene-Silane Adduct with the Chloride Ion

When a cold (-78˚C) solution of boraindene 1-4 and excess silane was treated with one equivalent (relative to 1-4) of bis-(triphenylphosphine)iminium chloride (PPNCl), the PPN+ salt of the hydridoborate anion 4-2 formed quickly and quantitatively (Scheme 44). Following

104 recrystallization from toluene and pentane, 4-2 was isolated in 73% yield. Spectroscopic evidence supports the formation of a hydridoborate, with a doublet in the 11B NMR (-16.2 ppm)

1 1 19 and a broad, 1:1:1:1 quartet in the H NMR (3.5 ppm, JBH = 90 Hz). The F NMR spectrum also indicates the formation of a single new species, with thirteen unique resonances. High- resolution mass spectrometry (HRMS) also confirms the presence of the 4-2 hydridoborate anion.

F F F F F C F 5 6 F5C6 F + Si F5C6 F Si B H B H F F5C6 1-4 C6F5 C6F5 4-1

PPNCl PPNCl

F F F F F PPN F5C6 F PPN Et3SiH F5C6 F Si B F + Cl F C B 5 6 Cl F C C F 5 6 H 6 5 4-3 C F 6 5 4-2 Ph Ph Ph PPN P N P Ph Ph Ph

Scheme 44. Reactions of 1-4 with PPNCl in both the presence and absence of Et3SiH

The chloroborate 4-3 that results from the reaction between boraindene 1-4 and PPNCl was not observed in the above reaction mixture. This was demonstrated by making it separately from the direct reaction of 1-4 and PPNCl in CH2Cl2; this reaction apparently takes only about five minutes at room temperature judging from the loss of the red colour of 1-4 from the solution. The reaction appears to be nearly quantitative by 19F NMR, and the white solid 4-3 was

105 11 isolated in 91% yield after recrystallization from CH2Cl2/pentane. The B NMR resonance appears as a relatively sharp singlet at -2.4 ppm, and HRMS confirms the presence of the chloroborate anion.

In an attempt to gauge the relative rates of reaction of PPNCl with boraindene 1-4 and its silane adduct 4-1, a 1:1 toluene-d8 solution of 1-4:Et3SiH was combined with one equivalent of

PPNCl. At room temperature, the equilibrium constant Ka is 1.13, which corresponds to a speciation of 4-1 of only 2.7%. Given the apparent speed at which PPNCl reacts with 1-4, we were surprised to find that the hydridoborate 4-2 forms exclusively as judged by 19F NMR

(Figure 48). The 11B NMR spectrum is consistent with this outcome as well, and 1H NMR spectrum confirms that the sole silane by-product is Et3SiCl (Figure 47). This indicates that the reaction of PPNCl with 4-1 is over 30 times faster than with free boraindene. However, when one considers the rapid rate at which B(C6F5)3 catalyzes the hydrosilation of imines and carbonyls, it is clear that these borane-silane adducts are very reactive towards nucleophiles.

1 Figure 47. H NMR spectra (toluene-d8) of: Et3SiCl (top) and the stoichiometric reaction mixture of 1-4, Et3SiH, and PPNCl (bottom). *Unreacted Et3SiH

106

19 Figure 48. F NMR spectra (toluene-d8) of 4-3 (top), 4-2 (middle), and the stoichiometric reaction of 1-4, Et3SiH, and PPNCl (bottom).

4.3.2 Boraindene-catalyzed Hydrosilations of Olefins

Given the relatively favourable formation of the boraindene-silane adduct 4-1, we naturally endeavoured to assess the catalytic activity of boraindene 1-4 towards the hydrosilation of unsaturated functional groups. Unfortunately, aldehydes and ketones react with 1-4 rapidly to form intractable mixtures, so we turned our attention to olefins. As discussed in Chapter 3, 1-4 reacts with cyclohexene, albeit slowly. Monosubstituted olefins have also proven to react rapidly with 1-4 to give mixtures of products, while tri- and tetra-substituted olefins appear to be

107 unreactive towards 1-4. However, we reasoned that 1-4 could be kinetically protected with increased concentration of Et3SiH, so the catalytic experiments were performed under solvent- free conditions. In all cases, stoichiometric amounts of liquid olefins were added to solutions of

Et3SiH containing 1 – 4 mol % of boraindene 1-4 (Scheme 45).

Indeed, even the monosubstituted olefin t-butylethylene appeared to undergo hydrosilation to give primarily (> 90%) the anti-Markovnikov product 4-4 within 90 minutes.

Minor amounts of other species are detected in the 1H and 13C spectra of the reaction mixtures, and the catalyst was appreciably (ca. 30%) decomposed. However, when the same reaction was attempted in CDCl3, no hydrosilation was detected after 3 hours, and the catalyst was completely destroyed; CDCl3 solutions of 1-4 and excess silane are stable for more than 3 hours.

Hydrosilation of 1,1-diphenylethylene gave 4-5 in quantitative yield within 90 minutes, with no side-products detected in the 1H and 13C NMR spectra, and only minor decomposition of the catalyst. Cyclohexene, was hydrosilated in close-to-quantitative yields and with little decomposition of the catalyst. At this point only an indirect comparison to B(C6F5)3-catalyzed hydrosilation of olefins reported by Gevorgyan et al is possible; their catalytic conditions were

typically 5-10 mol % B(C6F5)3 in CH2Cl2, though the hydrosilation of styrene took 10-12 hours.182

F F C F t-butylethylene 5 6 SiEt 4-4 < 1.5 hr, 1 mol % cat. F 3 F5C6 B H F Ph Ph SiEt C6F5 3 1,1-diphenylethylene H 4-5 < 1.5 hr, 1 mol % cat. Ph 1-4 Ph

H Et3SiH cyclohexene (neat) 4-6 < 6 hr, 1 mol % cat SiEt3

Scheme 45. Hydrosilation of t-butylethylene, 1,1-diphenylethylene, and cyclohexene 108 4.4 Conclusions

The first direct evidence of a silane-borane adduct has been presented here. Boraindene 1-4 and

o -1 Et3SiH reversibly form the adduct 4-1 with thermodynamic parameters ΔH = -29.7(3) kJ mol and ΔSo = 100(1) J mol-1 K-1. The Si-H-B bonding interaction in 4-1 is supported by 1H NMR spectroscopy, IR spectroscopy and X-ray diffraction, an interaction which is made possibly by the very high Lewis acidity of the parent boraindene 1-4. Adduct 4-1 reacts preferentially with the chloride ion over 1-4, and is also prone to nucleophilic attack by olefins, making 1-4 an active catalyst for hydrosilation.

109

Chapter Five: Conclusions and Future Work

5.1 Conclusions

Chapter 2 of this dissertation detailed the synthesis and properties of boraindenes, a new class of boroles with very high Lewis acidity as measured by the Gutmann-Beckett parameter.

This was attributed to both the anti-aromatic character and the ring strain of the compounds.

Synthesis of several derivatives revealed that marginal tuning of the electronic structure was possible by changing the aryl substituents at the 2- and 3- positions.

Chapter 3 illuminated the ways in which pentaarylboroles 1-1 and 1-2, and boraindene 1-

+ 4 activate molecular hydrogen. Mimicking the reactions with H2 by sequential reactions with H then H- showed that both classes of compounds undergo ring-opening and ring-closing as a result of H2 activation. In the case of boroles, the activation of H2 is bimolecular and irreversible. In the case of boraindenes, the activation of H2 appears to be reversible, though only the reverse reaction is strongly supported by experiment; the forward reaction is supported computationally.

Furthermore, boraindene 1-4 was found to mediate the hydrogenation of cyclohexene, though its role as a catalyst is in serious question. The fact that 1-4 reacts with cyclohexene, and the fact that this reaction product can also mediate the hydrogenation of cyclohexene, suggest that 1-4 is most likely a pre-catalyst.

Chapter 4 focused on the activation of the Si-H bond of triethylsilane by boraindene 1-4.

This activation was found to be reversible and was characterized in both the solution and solid states, with the crystal structure of the silane adduct 4-1 providing direct evidence for silane-

110 borane interactions involving a Si-H-B three-centre, two-electron bond. Preliminary experiments also suggest that 1-4 is a highly active catalyst for the hydrosilation of olefins.

The preceding work has resulted in the publication of three peer-reviewed articles and a third that is currently under review:

• Fukazawa, A.; Dutton, J. L.; Fan, C.; Mercier, L. G.; Houghton, A. Y.; Wu, Q.; Piers, W.

E.; Parvez, M., Chem. Sci. 2012, 3 (6), 1814-1818. (Chapter 1)

• Houghton, A. Y.; Karttunen, V. A.; Fan, C.; Piers, W. E.; Tuononen, H. M., J. Am. Chem.

Soc. 2013, 135 (2), 941-947. (Chapter 3)

• Houghton, A. Y.; Karttunen, V. A.; Piers, W. E.; Tuononen, H. M., Chem. Commun.

2014, 50 (11), 1295-1298. (Chapters 2 & 3)

• Houghton, A.Y.; J. Hurmalainen, A. Mansikkamäki, W. E. Piers, H. M. Tuononen,

Nature Chemistry. 2014. Accepted, NCHEM-14061059. (Chapter 4)

5.2 Future Work

The work presented in this thesis added a new class of highly Lewis-acidic organoboranes – boraindenes – to the world’s library of organometallic compounds. It also expanded our understanding of anti-aromatic compounds and how they can participate in H-H and Si-H bond- activation. As with any scientific endeavour, these discoveries have inspired new lines of inquiry, just as each chapter herein built upon its predecessor. The following is a proposal for a potential extension of anti-aromatic organoboron chemistry.

5.2.1 Boraindene Derivatives

Boraindenes have proven to show interesting properties and reactivity, but the extent to which they may be modified remains largely unexplored. An expansion of the “boraindene library”

111 should be readily achievable because of the adaptability of the synthetic routes outlined in

Chapter 2. For situations where these routes prove inadequate, alternate routes (to be discussed below) are also available.

Substitution at the 2- and 3- positions has shown marginal impact on the electronic structure of boraindenes, though only para-substituted phenyl groups have been explored.

Beyond this type of substituent, electron-rich heterocycles such as thiophenes and pyrroles are attractive because it has been shown that such groups can not only induce a significant decrease in the HOMO-LUMO gap of boroles but also an increase in the absorptivity.137 The introduction of Lewis-basic heteroatoms such as sulfur and nitrogen may prove problematic due to the potential to coordinate any available boron centre. Fortunately the Yamaguchi group has developed a protocol to circumvent this: following formation of the zirconaindene 5-1, oxidation with I2 would give diiodide 5-2, which could then be dilithiated and closed upon a dihaloborane such as MesBCl2 (Mes = 2,4,6-trimethylphenyl) (Scheme 46) to give boraindene 5-3. A large aryl group on boron is necessary to protect it from Lewis bases, though it would prevent the target compounds from acting as strong Lewis acids.

Ar Ar I Ar 1) nBuLi I2 Ar B Ar Zr 2) Ar Cl Cl I B Cp Cp 5-2 5-3 5-1 H S N Ar = ,

Scheme 46. Proposed synthesis of 5-3

112 The 2- and 3- positions of boraindene are also potential locations for the installation of additional Lewis-acidic centres. For example, the installation of two –B(C6F5)2 groups

(compound 5-4, ) would likely draw even more electron density away from the boraindene fragment than the two –C6F5 groups of 1-4, making the boron at the 1-position even more Lewis acidic. Furthermore, the two boryl substituents are reminiscent of the bifunctional Lewis acids that Piers and coworkers showed could be co-initiators for olefin polymerization.217-219

Compound 5-4 would be a tri-functional Lewis acid with three chemically inequivalent boron centres, an unprecedented type of compound. It could be synthesized by the same general route as for 1-4, in which 5-4 would be formed from the bis(dibromoboryl) boraindene 5-5 and

Zn(C6F5)2 (Scheme 47). Compound 5-5 would be available from a transmetallation reaction between BBr3 and bis(trimethylstannyl) stannaindene 5-6, which would ultimately come from

Cp2Zr(o-C6HF4)2 and bis(trimethylstannyl)acetylene, a commercially available compound.

C F 6 5 Br C F B 6 5 Br SnMe F4 B F 3 F4 C F F4 4 6 5 Br Zr B B SnMe H B B Sn 3 2 + C6F5 Zn(C F ) Br BBr Me Me 6 5 2 Br 3 Me Sn SnMe F5 3 3 5-4 5-5 5-6

Scheme 47. Retrosynthesis and suggested synthesis of 5-4.

5.2.2 A New Direction for Anti-Aromatic Boron Chemistry: “B-N Boraindenes”

The Piers group has had a long-standing interest in “B-N” organic compounds,63, 220-226 in which non-polar carbon-carbon units are transposed with polar boron-nitrogen units. Such compounds are isoelectronic with their all-carbon analogues, but possess much different properties. An

113 illustrative example is the ammonia-borane adduct (H3NBH3), a promising hydrogen storage

227 material that is isoelectronic with ethane (H3CCH3). Ethane is a gas at room temperature, has no dipole moment, and has hydrogen atoms that are weakly acidic. Ammonia-borane is very polar (4.9 debye in dioxane)228 and contains boron-bound hydrogen atoms which are hydridic as well as nitrogen-bound hydrogen atoms which are acidic, leading to strong intermolecular BH-

HN interactions. As a result of these interactions, ammonia-borane is a solid at room temperature.

The transposition of C-C units for B-N units has also proven to be an effective strategy by which to modify the photophysical properties of polyaromatic hydrocarbons (PAH), a promising class of materials for organic device applications.79, 138 Particularly striking examples of this are the B-N analogues of phenanthrene (Scheme 48): B-N substitution at the 9- and 10- positions results in a marginal hypsochromic shift of the fluorescence maximum, while substitution at the 4a- and 4b- positions results in a significant bathochromic shift of the fluorescence maximum.221 Furthermore, both B-N analogues have greatly enhanced fluorescence quantum yields compared to phenanthrene.

H H N B

N B

9-aza-10-bora- 4a-aza-4b-boraphenanthrene phenanthrene phenanthrene

λem = 347 nm λem = 327 nm λem = 450 nm Φem = 0.09 Φem = 0.61 Φem = 0.58

Scheme 48. Comparison of the photophysical properties of phenantrene, 9-aza-10- boraphenanthrene and 4a-aza-4b-boraphenanthrene.

114 While the impact of B-N units on organic aromatic systems has received much attention,227 very little is known about anti-aromatic B-N compounds. To date, there are only a few examples of “B-N-Boroles” which are more appropriately called diboraazoles. These examples include (and may even be limited to) the 1,3-diboraisoindoles reported by Siebert229 in

1974 (Scheme 49), which have only been characterized by 1H NMR spectroscopy, mass spectrometry and elemental analysis; nothing is known about either their photophysical properties nor their reactivity.

Me Me Me B B S N N Ph B Me B Me Me Me

Scheme 49. Previously reported “B-N Boraindnes”

In this context, a worthwhile extension of the work presented here would be to expand our investigations to “B-N boraindenes” (or 1,3-diboraisoindoles). The replacement of the 2- and 3- carbons in boraindenes with B-N units (Scheme 50) replaces the weakly basic olefinic bond with the lone pair of nitrogen while also adding an electrophilic boron centre. While the significant change in the electronic structure might result in new photophysical properties, it is more interesting to consider how the hypothetical reaction with H2 might proceed. Instead of the hydridoborate/carbocation intermediate VI, 1,3-diboraisoindole 5-7 would likely convert to the hydridoborate/ammonium intermediate 5-8, which could potentially undergo ring opening to form 5-9. The increased Lewis basicity of nitrogen should lower the energy of the heterolytic cleavage of the H-H bond, increasing both the forward and reverse rates of hydrogen cleavage.

115 Furthermore, both 5-8 and 5-9 feature a hydridic B-H and protic N-H in close proximity, which could provide a stabilizing effect absent in intermediates IV and VI.

R' R' R' H B R ? B R B R1-4 + H2 H 1-4 1-4 N N R" N R" B H B - H2 R" B 5-8 R' H R' 5-9 5-1 5-7 R'

F C F F 5 6 F F F5C6 F C F F F5C6 5 6 + H2 H H F H F F C F H 5 6 B B B F F - H2 F5C6 F IV 1-4 C F C6F5 VI 6 5 C6F5

Scheme 50. Hypothetical reaction of 5-7 with H2 compared to reaction of 1-4 with H2

A potential pitfall of this endeavour might originate from the donation of the lone pair on nitrogen into the empty p-orbitals on the two boron atoms, thus attenuating their Lewis acidity.11

However, anti-aromaticity tends to prevent π-delocalization,95 so it may induce the localization of the non-bonding electron pair. In either case, this work stands to at least uncover the properties of the largely unexplored B-N-B anti-aromatic systems.

The synthesis of these systems is both eminently feasible and highly adaptable. In addition to the route detailed by Siebert et al.,229 which culminates in a nitrogen-sulfur exchange reaction with 5-10 (Scheme 51) and an amine, one may obtain 5-7 by a transmetallation reaction between a bis(trimethylstannyl)amine230-232 (5-11) and a 1,2-bis(dibromoboryl)benzene233-234 (5-

12). Several examples of both types of compounds are known, and methodology for reacting 5-

11 with bromoboranes is well-developed.235 Furthermore, both synthetic routes allow for a greater degree of variability than those for boraindenes. The R” groups on nitrogen may be modified with the simple choice of amine, while the R’ groups on boron may be introduced by

116 the reaction of the appropriate organometallic reagent (e.g. CuR’, ZnR2’ etc…) with a boron- halogen bond. It may even be possible to install different R’ groups on the same molecule with the sequential reaction of different M-R’ compounds. Finally, the groups on the fused arene ring may be incorporated by starting with the appropriately substituted ortho-dihalobenzene 5-13.

R' R' SnMe3 B Br B R1-4 R1-4 B R1-4 2 R" N S N R" Br2B + SnMe3 B B 5-12 R"-NH2 + 5-10 5-7 5-11 R' R'

B R1-4 R1-4 X R"-NH2 + Me SnCl R1-4 B X 3 5-13 I

Scheme 51. Retrosynthesis of 5-7

117

Chapter Six: Experimental Details

6.1 General Considerations

All manipulations were carried out under a purified argon atmosphere either on a double manifold vacuum line or in a glove box. Argon, hydrogen and deuterium gas were purchased from PRAXAIR and passed through a Matheson TriGas® cartridge (model M641-02) prior to use on a vacuum line. Toluene, hexanes and THF were purified before use with the Grubbs/Dow purification system and stored with an indicator (Na/Ph2CO). Dichloromethane was dried over calcium hydride and stored over molecular sieves and stored under vacuum. Benzene and diethyl ether were dried and stored over Na/Ph2CO. All proteo solvents were stored under vacuum in 500 ml thick-walled glass vessels each equipped with a Kontes tap. Deuterated solvents were purified and stored in an analogous fashion. All solvents were distilled under vacuum prior to use.

Commercially available compounds were purchased from Aldrich, Strem, Boulder

Scientific, Fisher Scientific, or TCI America. Solids were typically purified by sublimation or dried over molecular sieves as a solution. Liquids were typically dried over molecular sieves and either distilled or filtered. All glassware was dried prior to use at 135˚C for a minimum of four hours and placed under vacuum while still hot.

6.2 Instrumentation

Nuclear magnetic resonance spectroscopy (1H, 11B, 13C, 19F, 31P, 29Si, 119Sn) was performed on either a Bruker 400 MHz or 600MHz instrument. Chemical shifts for 1H and 13C spectra are calibrated to the residual proton and carbon resonances of the solvent in accordance with Fulmer

118 and coworkers. Chemical shifts for other nuclei were calibrated with MestreNova’s ® absolute reference function. Kinetic and thermodynamic data were processed with Microsoft Excel 2008 for Mac. X-Ray crystallography was carried out on either a Nonius Kappa CCD diffractometer

using graphite-monochromated Mo Kα radiation or a Bruker Smart APEX II three-circle

diffractometer using Cu Kα radiation. More details on individual structures may be found in

Appendix A. Thermal ellipsoid illustrations were generated with Mercury 3.3 for Mac. UV/Vis spectra were obtained on a Varian Carey 5000 UV-vis-NIR spectrophotometer operating in single-beam mode. Infrared spectra were obtained on a Nicolet Avatar IR spectrophotometer.

Elemental analyses (C, H, N) were performed by Mr. Jianjun Li on a Perkin-Elmer Model 2400 series II analyzer. High-resolution mass spectra were obtained by Mrs. Dorothy Fox on a Kratos

MS-80 spectrometer via electron impact (EI) or by Mrs. Qiao Wu on a Bruker Autoflex III using

MALDI-TOF with a Smartbeam laser system.

6.2.1 NMR Data Reporting

1H and 19F NMR data are reported as follows: chemical shift in ppm (multiplicity, integration, coupling constants in Hertz, assignment (if any)); e.g. -155.39 (t, J = 20.8 Hz, 1F, p-C6F5).

3 3 Unless specified otherwise, coupling is assumed to be homonuclear, i.e. “ JHH or JFF would appear as J). For 13C NMR data, all signals are assumed to be singlets unless otherwise stated, integration is omitted, and the carbon atom is assigned either explicitly or by type (CH, CH2,

13 1 CH3, C (quaternary)). In all cases, C{ H} NMR spectra were run as DEPT-Q experiments.

6.2.2 Quantum Chemical Calculations

NICS calculations, TD-DFT and related structure optimizations were carried out with Gaussian

09 Revision A.1, M.J. Frisch, G.W. Trucks, H. B. Schlegel, G.E. Scuseria,M.A. Robb, J. R. 119 Cheeseman, G.Scalmani, V. Barone,B. Mennucci, G.A. Petersson, H. Nakatsuji, M. Caricato, X.

Li, H.P. Hratchian, A. F. Izmaylov,J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara,

K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T.

Vreven, J.A. Montgomery, Jr., J.E. Peralta, F. Ogliaro, M. Bearpark, J.J. Heyd, E. Brothers, K.N.

Kudin, V.N. Staroverov, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J.C. Burant,

S.S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J.M. Millam, M. Klene, J.E. Knox, J.B. Cross, V.

Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann, O.Yazyev, A.J. Austin,R.

Cammi, C. Pomelli, J.W. Ochterski, R.L. Martin, K. Morokuma, V.G. Zakrzewski, G.A. Voth, P.

Salvador, J.J. Dannenberg, S. Dapprich, A.D. Daniels, Ö. Farkas, J. B. Foresman, J.V. Ortiz, J.

Cioslowski, and D.J. Fox, Gaussian, Inc., Wallingford CT, 2009.

All other calculations were performed by Heikki M. Tuononen and Virve. A Karttunen at the

University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland.

6.3 Experimental Details for Chapter 2

6.3.1 Synthesis of Boraindene 1-3 & Derivatives

6.3.1.1 Synthesis of Cp2ZrPh2

A solution of phenyllithium (60.0 mL, 1.8 M in Bu2O, 108 mmol) was added via syringe pump over two hours to a vortexing slurry of Cp2ZrCl2 (15.5 g, 53.0 mmol) in Et2O (300 mL) at -40˚C.

After the mixture was allowed to reach room temperature, the LiCl was filtered off and the volatiles were removed in vacuo. The LiCl was washed with CH2Cl2, filtered, then the filtrate combined with the crude product. Following removal of the volatiles, the solids were washed

120 with hexanes (50 mL), giving Cp2ZrPh2 as a tan solid (15.5 g, 77.9% yield). Spectroscopic data matched that reported in the literature (Erker, J. Organomet. Chem. 1977, 134 (2), 189-202).

6.3.1.2 Synthesis of Zirconaindenes

General Procedure. A Kontes vessel was charged with a solution containing Cp2ZrPh2 and diarylacetylene (1.00 equivalents) in toluene (ca. 5 mL / mmol Cp2ZrPh2) and heated at 110˚C for 20 hours. The volume of the mixture was reduced in vacuo to <10% of its original value, until solids began to form. The remaining solution was decanted and the solids (typically yellow to orange) were washed with hexanes (2x) then dried in vacuo.

6.3.1.2.1 1,1-bis(cyclopentadienyl)-2,3-diphenyl-1-zirconaindene (2-9)

Cp Cp

Spectroscopic data matched that reported in the literature (Boudjouk, Organometallics. 2000, 19,

1806-1809).

6.3.1.2.2 1,1-bis(cyclopentadienyl)-2,3-bis(4-methylphenyl)-1-zirconaindene (2-9CH3).

H3C

H3C Zr Cp Cp

121 Isolated an orange powder (83% yield), x-ray quality crystals obtained by slow evaporation from

1 CH2Cl2. H NMR (400 MHz, CD2Cl2) δ 6.99 (m, 2H), 6.93 – 6.88 (m, 2H), 6.88 – 6.83 (m, 2H),

6.82 – 6.75 (m, 2H), 6.70 – 6.65 (m, 1H), 6.59 – 6.52 (m, 3H), 6.36 (s, 10H), 2.27 (s, 3H, CH3),

13 2.18 (s, 3H, CH3). C NMR (101 MHz, CD2Cl2) δ 194.85 (Zr-C), 185.48 (Zr-C), 147.74 (C),

146.14 (C), 144.30 (C), 139.07 (C), 136.62 (aryl CH), 135.04, 132.18, 130.51 (aryl CH), 128.71

(aryl CH), 128.42 (aryl CH), 126.63 (aryl CH), 125.15 (aryl CH), 124.91 (aryl CH), 123.61 (aryl

CH), 113.10 (Cp), 21.25 (CH3), 20.94 (CH3). Elemental analysis (%) for C32H28Zr: Calculated C

76.29 H 5.60, Found C 75.62 H 6.06.

6.3.1.2.3 1,1-bis(cyclopentadienyl)-2,3-bis(4-trifluoromethylphenyl)-1-zirconaindene (2-9CF3)

F3C

F3C Zr

Cp Cp

Isolated an orange powder (80% yield), X-ray quality crystals obtained by slow evaporation from

1 toluene. H NMR (400 MHz, CD2Cl2) δ 7.47 – 7.37 (m, 2H), 7.32 – 7.26 (m, 2H), 7.14 (dt, J =

7.9, 0.9 Hz, 2H), 6.87 – 6.81 (m, 2H), 6.80 – 6.74 (m, 2H), 6.73 – 6.69 (m, 1H), 6.57 – 6.52 (m,

13 1H), 6.41 (s, 10H, Cp). C NMR (101 MHz, CD2Cl2) δ 193.34 (Zr-C), 185.64 (Zr-C), 151.37

(C), 146.16 (C), 145.25 (C), 145.05 (C), 136.86 (C), 130.89 (aryl CH), 126.57 (aryl CH), 125.45

3 3 (aryl CH), 125.36 (aryl CH), 125.10 (q, JFC = 3.8 Hz, HC-C-CF3), 124.78 (q, JFC = 3.8 Hz, HC-

C-CF3), 124.37 (aryl CH), 113.54 (Cp), resonances for CF3 and C-CF3 not observed due to

19 1 coupling to fluorine. F{ H} NMR (376 MHz, CD2Cl2) δ -64.07 (s, 3F, CF3), -64.37 (s, 3F,

+ CF3). HRMS (TOF MS EI+) for C32H22F6Zr: Calculated M 610.0673, Found 610.0651.

122

6.3.1.2.4 1,1-bis(cyclopentadienyl)-2,3-bis(4-fluorophenyl)-1-zirconaindene (2-9F)

F Zr

Cp Cp

1 Isolated an orange solid (98% yield). H NMR (400 MHz, CD2Cl2) δ 7.04 – 6.97 (m, 2H), 6.94 –

6.88 (m, 2H), 6.88 – 6.84 (m, 2H), 6.83 – 6.76 (m, 2H), 6.75 – 6.72 (m, 1H), 6.69 – 6.58 (m,

13 3H), 6.42 (s, 10H, Cp). C NMR (101 MHz, CD2Cl2) δ 193.63 (Zr-C), 185.20 (Zr-C), 161.23 (d,

1 1 JFC = 176 Hz, CF), 158.83 (d, JFC = 171 Hz, CF), 146.68 (C), 145.41 (C), 143.11 (C), 137.30

3 3 (C), 136.30, 131.77 (d, JFC = 7.6 Hz, HCCCF), 127.56 (d, JFC = 7.4 Hz, HCCCF), 124.91 (aryl

2 2 CH), 124.67 (aryl CH), 123.57 (aryl CH), 114.34 (d, JFC = 20.8 Hz, HCCF), 114.11 (d, JFC =

19 21.0 Hz, HCCF), 112.82 (Cp). F NMR (376 MHz, CD2Cl2) δ -120.01 (s, 1F), -123.64 (s, 1F).

+ HRMS (TOF MS EI+) for C30H22F2Zr: Calculated M 510.0737, Found 510.0714.

6.3.1.2.5 1,1-bis(cyclopentadienyl)-2,3-bis(4-methoxyphenyl)-1-zirconaindene (2-9OCH3)

H3CO

H3CO Zr

Cp Cp

1 Isolated an orange-red solid (98% yield). H NMR (400 MHz, CD2Cl2) δ 6.97 – 6.90 (m, 2H),

6.86 – 6.76 (m, 2H), 6.75 – 6.70 (m, 2H), 6.70 – 6.63 (m, 2H), 6.64 – 6.59 (m, 2H), 6.55 – 6.50

123 13 (m, 2H), 6.36 (s, 10H), 3.74 (s, 3H, OCH3), 3.68 (s, 3H, OCH3). C NMR (101 MHz, CD2Cl2) δ

194.64 (Zr-C), 185.65 (Zr-C), 157.79 (C), 155.89 (C), 147.98 (C), 146.25 (C), 139.84 (aryl CH),

136.63 (C), 134.52 (aryl CH), 131.77 (aryl CH), 127.90 (aryl CH), 125.18 (aryl CH), 124.86

(aryl CH), 123.63 (aryl CH), 113.52 (aryl CH), 113.14 (aryl CH), 113.03 (Cp), 55.37 (OCH3),

55.33 (OCH3).

6.3.1.2.6 1,1-bis(cyclopentadienyl)-2,3-bis(pentafluorophenyl)-1-zirconaindene (2-9C6F5)

F5C6

F5C6 Zr

Cp Cp

Isolated a yellow powder (93% yield). X-ray quality crystals were grown from the

1 hexanes/toluene washes by adding CH2Cl2 until the solids dissolved, then storing at -30˚C. H

NMR (400 MHz, CH2Cl2) δ 6.96 – 6.88 (m, 2H), 6.80 – 6.74 (m, 1H), 6.54 – 6.50 (m, 1H), 6.47

13 (s, 10H, Cp). C NMR (101 MHz, CH2Cl2) δ 186.13 (Zr-C), 180.29 (Zr-C), 143.32 (C), 137.30,

134.74 (C), 125.97 (aryl CH), 125.51 (aryl CH), 124.67 (aryl CH), 114.18 (Cp), C6F5 carbons

19 1 not observed due to coupling to fluorine. F{ H} NMR (376 MHz, CH2Cl2) δ -140.64 (m, 2F, o-

C6F5), -141.82 (dq, J = 24.9, 8.2 Hz, 2F, o-C6F5), -157.01 (t, J = 20.8 Hz, 1F, p-C6F5), -161.51 (t,

J = 21.0 Hz, 1F, p-C6F5), -163.13 (m, 2F, m-C6F5), -163.51 (m, 2F, m-C6F5). HRMS (TOF EI+)

+ for C30H14F10Zr: Calculated M 653.9983, Found 653.9963.

6.3.1.3 Synthesis of Stannaindenes

General Procedure. A Kontes thick-walled glass vessel was charged with a solution containing zirconaindene and Me2SnCl2 (1.05-1.10 equivalents) in THF (ca. 5 mL / mmol zirconaindene)

124 and heated at 80˚C for 24 hours. The volatiles were removed in vacuo at 60˚C to get rid of unreacted Me2SnCl2, then the crude product was taken up in CH2Cl2 (in air) and passed through florisil (15 mL / mmol product). Pure product was obtained by recrystallization.

6.3.1.3.1 1,1-dimethyl-2,3-diphenyl-1-stannaindene (2-7)

Sn Me Me

Re-crystallized from layered CH2Cl2/methanol at room temperature to yield a white solid (50%).

1 H NMR (400 MHz, CD2Cl2) δ 7.75 – 7.60 (m, 1H), 7.38 – 7.14 (m, 7H), 7.13 – 7.06 (m, 2H),

2 13 7.04 – 6.97 (m, 1H), 6.97 – 6.88 (m, 3H), 0.60 (s, JSnH = 60 Hz, 6H, Sn-CH3). C NMR (101

MHz, CD2Cl2) δ 152.42 (C), 151.57 (C), 146.66 (C), 143.50 (C), 140.16 (C), 140.03 (C), 135.23

(aryl CH), 130.12 (aryl CH), 128.58 (aryl CH), 128.48 (aryl CH), 128.19 (aryl CH), 127.74 (aryl

CH), 126.92 (aryl CH), 126.58 (aryl CH), 126.54 (aryl CH), 125.01 (aryl CH), -8.57 (Sn-CH3).

119 1 Sn{ H} NMR (149 MHz, CD2Cl2) δ -11.03. HRMS (MALDI-TOF) for C22H20Sn: Calculated

(M+H)+ 405.0660, Found 405.0671.

6.3.1.3.2 1,1-dimethyl-2,3-bis(4-methylphenyl)-1-stannaindene (2-7CH3)

H3C

H3C Sn Me Me

125 Recrystallized from layered CH2Cl2/methanol at -15˚C to yield a colourless crystalline solid

(51% yield). Crystals suitable for X-ray analysis were grown by slow evaporation from CH2Cl2.

1 H NMR (400 MHz, CD2Cl2) δ 7.71 – 7.55 (m, 1H), 7.28 – 7.10 (m, 4H), 7.08 – 6.99 (m, 2H),

6.95 – 6.85 (m, 3H), 6.85 – 6.77 (m, 2H), 2.37 (s, 3H, C6H4-CH3), 2.22 (s, 3H, C6H4-CH3), 0.56

2 13 (s, JSnH = 60 Hz, 6H SnCH3). C NMR (101 MHz, CD2Cl2) δ 152.40 (C), 152.27 (C), 146.68

(C), 140.82 (C), 140.32 (C), 137.75 (C), 136.67 (C), 135.59 (aryl CH), 135.21 (C), 130.37 (aryl

CH), 129.40 (aryl CH), 129.04 (aryl CH), 128.94 (aryl CH), 127.16 (aryl CH), 126.85(aryl CH),

119 1 21.40 (C6H4-CH3), 21.12 (C6H4-CH3), -8.18 (SnCH3). Sn{ H} NMR (149 MHz, CD2Cl2) δ

+ -13.46. HRMS (MALDI-TOF) for C24H24Sn: Calculated (M+H) 433.0973, Found 433.0974.

6.3.1.3.3 1,1-dimethyl-2,3-bis(4-(trifluoromethyl)phenyl)-1-stannaindene (2-7CF3)

F3C

F3C Sn Me Me

Recrystallized from layered CH2Cl2/methanol at -15˚C to yield a colourless crystalline solid

1 (69% yield) that was suitable for X-ray analysis. H NMR (600 MHz, CD2Cl2) δ 7.72 (m 1H),

7.64 – 7.58 (m, 2H), 7.41 – 7.36 (m, 2H), 7.34 – 7.28 (m, 3H), 7.25 (m, 1H), 7.03 (m, 2H), 6.93

13 – 6.88 (m, 1H), 0.63 (s, 6H). C NMR (151 MHz, CD2Cl2) δ 152.84 (C), 150.79 (C), 147.98 (C),

147.44 (C), 143.93 (C), 140.65 (C), 135.97 (aryl CH), 130.99 (aryl CH), 129.27 (aryl CH),

3 128.64 (aryl CH), 128.04 (aryl CH), 127.13 (aryl CH), 125.67 (q, JFC = 3.7 Hz, HCCCF3),

3 19 1 125.31 (q, JFC = 3.8 Hz, HCCCF3), -8.00 (SnCH3). F{ H} NMR (376 MHz, CD2Cl2) δ -64.48

126 119 1 8 (CF3), -64.60 (CF3). Sn{ H} NMR (149 MHz, CD2Cl2) δ -4.29 (q, JFSn = 4.4 Hz). HRMS

+ (MALDI-TOF) for C24H18F6Sn: Calculated (M+H) 541.0407, found 541.0428.

6.3.1.3.4 1,1-dimethyl-2,3-bis(4-fluorophenyl)-1-stannaindene (2-7F)

F Sn Me Me

Recrystallized from layered CH2Cl2/methanol at -15˚C to yield a colourless crystalline solid

(44% yield). Crystals suitable for X-ray analysis were grown by slow evaporation from CH2Cl2.

1 H NMR (400 MHz, CD2Cl2) δ 7.75 – 7.59 (m, 1H), 7.30 – 7.17 (m, 2H), 7.15 – 7.08 (m, 2H),

13 7.08 – 7.00 (m, 2H), 6.97 – 6.75 (m, 5H), 0.59 (s, 6H, SnCH3). C NMR (101 MHz, CD2Cl2) δ

1 1 162.83 (d, JFC = 114.5 Hz, CF), 160.40 (d, JFC = 114.0 Hz, CF), 152.09 (C), 151.64 (C), 146.73

3 (C), 140.32 (C), 139.84 (C), 136.19 (C), 135.77 (aryl CH), 132.23 (d, JFC = 7.8 Hz, HCCCF),

3 130.31 (d, JFC = 7.7 Hz, HCCCF), 129.10 (aryl CH), 127.55 (aryl CH), 126.84 (aryl CH),

2 2 19 1 115.62 (d, JFC = 21.2 Hz, HCCF), 115.06 (d, JFC = 21.3 Hz, HCCF), -8.18 (SnCH3). F{ H}

119 1 NMR (376 MHz, CD2Cl2) δ -116.35, -118.40. Sn{ H} NMR (149 MHz, CD2Cl2) δ -11.91 (d,

7 + JFSn = 6.9 Hz). HRMS (MALDI-TOF) for C22H18F2Sn: Calculated (M+H) 441.0471, Found

441.0470.

127

6.3.1.3.5 1,1-dimethyl-2,3-bis(pentafluorophenyl)-1-stannaindene (2-7C6F5)

F5C6

F5C6 Sn Me Me

Reaction was carried out in the presence of CuCl (2.0 equivalents). Product was recrystallized

1 from hot hexanes to yield a white solid (72% yield). H NMR (400 MHz, CD2Cl2) δ 7.86 – 7.70

2 (m, 1H), 7.47 – 7.32 (m, 2H), 7.00 – 6.91 (m, 1H), 0.82 – 0.57 (s, JSnH = 60 Hz, 6H, SnCH3).

13 C NMR (101 MHz, CD2Cl2) δ 147.15 (C), 141.02 (C), 136.30 (aryl CH), 129.72 (aryl CH),

1 129.19 (aryl CH), 125.91 (aryl CH), -7.46 (Sn-CH3, JSnC = 370, 355 Hz), C6F5 carbons not

19 assigned due to extensive coupling to fluorine. F NMR (376 MHz, CD2Cl2) δ -139.22 (dq, J =

20.9, 5.5 Hz, 2F, o-C6F5), -141.41 (m, 2F, o-C6F5), -154.75 (t, J = 20.7 Hz, 1F, p-C6F5), -158.42

(t, J = 20.7 Hz, 1F, p-C6F5), -162.04 (m, 2F, m-C6F5), -163.25 (ddd, J = 23.0, 20.3, 7.8 Hz, 2F,

119 m-C6F5). Sn resonance not observed due to coupling to fluorine. HRMS (MALDI-TOF) for

+ C22H10F10Sn: Calculated (M+H) 584.9718, Found 584.9699.

6.3.1.4 Synthesis of Boraindenes

General Procedure. A solution of PhBCl2 (1.1 equivalents) in CH2Cl2 was added dropwise over two minutes to a solution of stannaindene in CH2Cl2 and the resulting solution was stirred for 4-5 hours at room temperature. The volatiles were removed in vacuo and the Me2SnCl2 by-product was sublimed off at 60˚C. The product was then re-crystallized from CH2Cl2/hexanes at -30˚C.

128 6.3.1.4.1 1,2,3-triphenyl-1-boraindene 1-3

B Ph

1 Obtained a fluffy orange solid (69.7% yield). H NMR (400 MHz, CD2Cl2) δ 7.79 – 7.71 (m,

2H), 7.67 (ddd, J = 6.5, 1.4, 0.7 Hz, 1H), 7.57 – 7.47 (m, 1H), 7.42 – 7.27 (m, 5H), 7.20 – 7.06

13 (m, 5H), 7.01 – 6.91 (m, 2H), 6.85 – 6.76 (m, 1H). C NMR (151 MHz, CD2Cl2) δ 166.26 (C),

155.47 (C), 147.22 (C-B), 140.22 (C), 139.72 (C-B), 138.79 (C-B), 136.73 (aryl CH), 136.07

(C), 133.72 (aryl CH), 132.95 (aryl CH), 132.82 (aryl CH), 129.58 (aryl CH), 129.03 (aryl CH),

128.61 (aryl CH), 128.51 (aryl CH), 128.35 (aryl CH), 128.06 (aryl CH), 128.00 (aryl CH),

11 126.12 (aryl CH), 121.92 (aryl CH). B NMR (128 MHz, CD2Cl2) δ 58. HRMS (TOF EI+) for

+ C26H19B: Calculated M 342.1580, Found 342.1574.

6.3.1.4.2 1-phenyl-2,3-bis(4-methylphenyl)-1-boraindene 1-3CH3

H3C

H3C B Ph

1 Obtained a fluffy red solid (65.4% yield). H NMR (400 MHz, CD2Cl2) δ 7.79 – 7.72 (m, 2H),

7.68 – 7.62 (m, 1H), 7.55 – 7.48 (m, 1H), 7.42 – 7.34 (m, 2H), 7.20 – 7.07 (m, 6H), 7.03 – 6.95

13 (m, 2H), 6.90 – 6.78 (m, 3H), 2.36 (s, 3H, C6H4-CH3), 2.30 (s, 3H, C6H4-CH3). C NMR (101

MHz, CD2Cl2) δ 166.10 (C), 155.68 (C), 138.34 (C), 137.21 (C), 136.62, 135.67 (C), 133.53

129 (aryl CH), 133.20 (C), 132.85 (aryl CH), 132.64 (aryl CH), 129.48 (aryl CH), 129.20 (aryl CH),

128.99 (aryl CH), 128.72 (aryl CH), 128.66 (aryl CH), 128.44 (aryl CH), 128.01 (aryl CH),

121.79 (aryl CH), 21.53 (C6H4-CH3), 21.34 (C6H4-CH3), carbons adjacent to boron not observed

11 due to quadrupolar relaxation. B NMR (128 MHz, CD2Cl2) δ 65. HRMS (TOF EI+) for

+ C26H23B: Calculated M 370.1893, Found 370.1877.

6.3.1.4.3 1-phenyl-2,3-bis(4-(trifluoromethyl)phenyl)-1-boraindene 1-3CF3

F3C

F3C B

1 Obtained a red solid (54.9% yield). H NMR (400 MHz, CD2Cl2) δ 7.81 – 7.67 (m, 3H), 7.66 –

7.59 (m, 2H), 7.58 – 7.53 (m, 1H), 7.50 – 7.31 (m, 6H), 7.20 (m, 2H), 7.08 (m, 2H), 6.85 – 6.75

13 (m, 1H). C NMR (101 MHz, CD2Cl2) δ 165.15 (C), 154.13 (C), 143.31 (aryl CH), 139.06 (aryl

CH), 136.33 (aryl CH), 133.91 (aryl CH), 132.90 (aryl CH), 132.85 (aryl CH), 129.41 (aryl CH),

3 129.01 (aryl CH), 128.80 (aryl CH), 127.85 (aryl CH), 125.32 (q, JFC = 3.8 Hz, HCCCF3),

3 124.70 (q, JFC = 3.8 Hz, HCCCF3) 121.69 (aryl CH), carbons adjacent to boron not observed due to quadrupolar relaxation, CCF3 and CCF3 carbons not observed due to extensive coupling.

11 19 1 B NMR (128 MHz, CD2Cl2) δ 65 F{ H} NMR (376 MHz, CD2Cl2) δ -62.59 (s, 3F), -62.98

(s, 3F). Elemental analysis (%) for C28H17BF6: Calculated C 70.32 H 3.58, Found 70.27 H 3.45.

+ HRMS (TOF EI+) for C28H17BF6: Calculated M 478.1328, Found 478.1340.

130 6.3.1.4.4 1-phenyl-2,3-bis(4-fluorophenyl)-1-boraindene 1-3F

F B Ph

1 Obtained a fluffy red solid (60.9%). H NMR (400 MHz, CD2Cl2) δ 7.78 – 7.72 (m, 2H), 7.71 –

7.65 (m, 1H), 7.53 (ddt, J = 8.9, 7.0, 1.4 Hz, 1H), 7.43 – 7.36 (m, 2H), 7.26 – 7.11 (m, 4H), 7.08

– 6.99 (m, 2H), 6.96 – 6.84 (m, 4H), 6.81 (dt, J = 7.2, 0.8 Hz, 1H). 13C NMR (101 MHz,

1 1 CD2Cl2) δ 165.42 (C), 163.46 (d, JFC = 112.4 Hz, CF), 161.02 (d, JFC = 108.9 Hz, CF), 155.04

(C), 136.70 , 135.95 (C), 133.85 (aryl CH), 133.05 (aryl CH), 132.95 (aryl CH), 131.83 (C),

3 3 131.18 (d, JFC = 7.8 Hz, HCCCF), 131.03 (d, JFC = 8.1 Hz, HCCCF), 128.80 (aryl CH), 128.16

2 2 (aryl CH), 121.83 (aryl CH), 115.66 (d, JFC = 21.5 Hz, HCCF), 114.99 (d, JFC = 21.1 Hz,

HCCF), carbons adjacent to boron not observed due to quadrupolar relaxation. 11B NMR (128

19 1 MHz, CD2Cl2) δ 65. F{ H} NMR (376 MHz, CD2Cl2) δ -113.69 (s, 1F), -117.59 (s, 1F).

+ HRMS (TOF EI+) for C26H17BF2: Calculated M 378.1391, Found 378.1400.

6.3.1.4.5 1-phenyl-2,3-bis(pentafluorophenyl)-1-boraindene 1-3C6F5

F5C6

F5C6 B Ph

Obtained a yellow solid (42% yield). Crystals suitable for x-ray analysis were grown from

1 CH2Cl2/hexanes at -30˚C. H NMR (400 MHz, CD2Cl2) δ 7.94 – 7.77 (m, 3H), 7.68 – 7.60 (m,

1H), 7.48 (dd, J = 8.3, 7.0 Hz, 2H), 7.37 – 7.22 (m, 2H), 6.78 – 6.65 (m, 1H). 13C NMR (101

131 MHz, CD2Cl2) δ 157.45 (C), 151.69 (C), 136.37 (aryl CH), 135.04 (aryl CH), 134.46 (aryl CH),

134.00 (aryl CH), 130.27 (aryl CH), 128.80 (aryl CH), 122.01 (aryl CH), signals missing from

C6F5 groups due to extensive coupling and carbons adjacent to boron due to quadrupolar

11 19 relaxation. B NMR (128 MHz, CD2Cl2) δ 63 (br). F NMR (376 MHz, CD2Cl2) δ -136.79 (m,

2F, o-C6F5), -138.32 (ddd, J = 21.1, 8.8, 5.2 Hz, o-C6F5), -151.55 (t, J = 20.9 Hz, 1F, p-C6F5), -

154.84 (t, J = 21.0 Hz, 1F, p-C6F5), -160.01 (m, 2F, m-C6F5), -161.38 (td, J = 22.4, 8.2 Hz, 2F,

+ m-C6F5). HRMS (TOF EI+) for C26H9BF10: Calculated 522.0638 M , Found 522.0646.

6.3.2 Synthesis of Boraindene 1-4

6.3.2.1 Synthesis of Cp2Zr(o-C6HF4)2.

F4 Zr H 2

A 250 mL, two-neck round-bottom flask (rbf) was charged with 1,2,3,4-tetrafluorobenzene (3.00 g, 20.0 mmol) and THF (80 mL). The solution was cooled to -78˚C and n-butyllithium (2.5 M in hexanes, 8.0 mL, 20.0 mmol) was added via syringe pump over 1.5 hours. WARNING! Do not let the solution warm above -30˚C so as to avoid the explosive elimination of LiF. The now black solution was allowed to stir for an additional 1.5 hours at -78˚C. A 250 mL, three-neck rbf was charged with zirconocene dichloride (2.915 g, 10.0 mmol) and THF (90 mL), and kept at -

78oC. A bubbler was connected to this flask, and the solution of (2,3,4,5- tetrafluorophenyl)lithium was transferred into it via cannula over one hour (the cannula was initially cooled down with a piece of dry ice). The temperature was maintained at -78oC for 3 hours and then allowed to gradually warm to room temperature overnight (i.e. the cold bath was

132 left in place). The solvent was removed in vacuo and the remaining grey solid was washed with hexanes (2 x 10 mL), taken up in CH2Cl2 (120 mL) and filtered through a swivel frit. The LiCl was washed with CH2Cl2, and the solvent was removed in vacuo. The resulting brown solid

1 19 (4.30 g, 8.30 mmol, 83.0 % crude yield) was ~90% pure Cp2Zr(o-C6HF4)2 by H and F NMR, which is sufficiently pure for the subsequent synthetic steps. Pure Cp2Zr(o-C6HF4)2 was

o obtained by recrystallization from layered CH2Cl2 and hexanes at -30 C as a light brown solid

(2.39 g, 4.61 mmol, 46.1 % yield). Crystals suitable for X-ray analysis were obtained from

1 CH2Cl2 and hexanes at -30˚C. H NMR (400 MHz, CD2Cl2) δ 6.57 (m, 2H, Zr(C6F4H)2), 6.37 (s,

19 1 10H, Cp-H). F{ H} NMR (376 MHz, CD2Cl2) δ -116.02 (ddd, J = 31.8, 16.7, 4.1 Hz), -143.25

(dd, J = 19.6, 16.8 Hz), -160.25 (dd, J = 31.8, 18.5 Hz), -161.62 (td, J = 19.1, 4.1 Hz). 13C{1H}

1 NMR (101 MHz, CD2Cl2) δ 156.31 (m), 148.77 (dm, JCF =221.2 Hz), 147.27 (ddd, J = 251.5,

9.7, 2.8 Hz), 140.02 (dddd, J = 259.6, 27.2, 11.8, 2.2 Hz), 138.80 (dddd, J = 249.5, 17.6, 12.7,

5.1 Hz), 114.27 (dddd, J = 22.1, 14.3, 5.4, 1.9 Hz), 113.55 (s). Elemental analysis (%) for

C22H12F8Zr: Calculated: C 50.86, H 2.33; Found C 50.43, H 2.45.

6.3.2.2 Synthesis of 1,1-bis(cyclopentadienyl)-2,3-bis(pentafluorophenyl)-4,5,6,7-tetrafluoro-1- zirconaindene 2-10.

Cp F5C6 F4 F5C6 Zr 2-10 Cp

In a Kontes thick-walled glass vessel, Cp2Zr(o-C6HF4)2 (2.38 g, 4.60 mmol) and [(C6F5)C]2

(1.64 g, 4.61 mmol) were taken up in toluene (30 mL). The mixture was stirred and heated at

110oC for 40 hours, after which time it was allowed to cool to room temperature. The solvent was reduced to a volume of ca. 5 mL and decanted. The solids were washed with hexanes (3 x 6

133 mL) and dried in vacuo to give a yellow powder (2.10 g, 2.89 mmol, 62.7 % yield). Crystals

o 1 suitable for x-ray analysis were obtained from toluene at -30 C. H NMR (400 MHz, CD2Cl2) δ

H 19 6.57 (s, 1H, Cp ). F NMR (376 MHz, CD2Cl2) δ -122.85 (dd, J = 34.0, 17.2 Hz, 1F), -141.01

(m, 2F, o-C6F5), -142.02 (td, J = 17.6, 2.6 Hz, 1F), -142.34 (m, 2F, o-C6F5), -156.85 (t, J = 20.7

Hz, 1F), -158.61 (t, J = 18.3 Hz, 1F), -159.09 (ddd, J = 34.0, 18.5, 2.7 Hz, 1F), -159.73 (t, J =

20.9 Hz, 1F), -162.68 (ddd, J = 23.3, 20.5, 7.4 Hz, 2F, m-C6F5), -163.74 (ddd, J = 23.3, 20.2, 7.8

13 vinyl Hz, 2F, m-C6F5). C NMR (101 MHz, CD2Cl2) δ 185.84 (s, Zr-C ), 157.00 (d, J = 62.1 Hz,

Zr-Caryl), 147.63 (dt, J = 6.9, 3.3 Hz), 146.54 – 145.87 (m), 145.45 (dt, J = 6.8, 3.2 Hz), 145.37 –

144.94 (m), 143.86 – 143.42 (m), 143.09 – 142.23 (m), 142.14 – 141.58 (m), 141.15 – 140.38

(m), 140.31 – 138.06 (m), 137.76 – 137.20 (m), 137.17 – 135.95 (m), 130.10 (s, Zr-C=Cvinyl),

Cp 126.19 (dd, J = 22.5, 5.5 Hz), 114.90 (s, C ). Elemental analysis (%) for C30H10F14Zr:

Calculated: C 49.52, H 1.39; Found C 49.26, H 1.58.

6.3.2.3 Synthesis of 1,1-dimethyl-2,3-bis(pentafluorophenyl)-4,5,6,7-tetrafluoro-1-stannaindene 2-8

Me F5C6 F4 F5C6 Sn 2-8 Me

In a Kontes thick-walled glass vessel, 2-10 (2.55 g, 3.51 mmol), CuCl (0. 695 g, 7.02 mmol) and

Me2SnCl2 (0.848 g, 3.86 mmol) were taken up in THF (15 mL) and the resulting slurry was

o stirred at 80 C for 48 hours. The solvent was removed in vacuo and the excess Me2SnCl2 was sublimed out of the flask at 55oC for 1 hour. Under ambient conditions, the remaining brown solids were taken up in wet CH2Cl2 and passed through Florisil (60 mL). Removal of the solvent gave a light yellow solid. Under an argon atmosphere, this solid was recrystallized from

134 hot (dry) hexanes, the mother liquor was decanted. the solid washed with cold hexanes (2 x 5 mL) and dried in vacuo to give an off-white solid (1.62 g, 2.47 mmol, 71.3 % yield). Crystals

1 suitable for x-ray analysis were obtained by slow evaporation from CH2Cl2. H NMR (400 MHz,

2 19 CD2Cl2) δ 0.78 (s, JSnH = 64.8 Hz, 62.8 Hz, 6H). F NMR (376 MHz, CD2Cl2) δ -119.53 (ddd, J

F F = 28.3, 16.8, 3.4 Hz, Ar ), -140.95 (m, 4F, o-C6F5), -141.21 (td, J = 17.6, 4.5 Hz, 1F, Ar ), -

152.80 (td, J = 18.3, 3.4 Hz, 1F, ArF), -153.25 (ddd, J = 28.3, 18.1, 4.6 Hz, 1F, ArF), -154.27 (t, J

= 20.7 Hz, 1F, p-C6F5), -156.52 (t, J = 20.8 Hz, 1F, p-C6F5), -162.25 (m, 2F, m-C6F5), -162.55

13 (m, 2F, m-C6F5). C NMR (101 MHz, CD2Cl2) δ 150.83 (m), 148.48 (m), 147.96 (m), 145.36

(m), 143.99 (m), 143.54 (m), 142.95 (m), 142.21 – 141.38 (m), 140.91 (d, J = 7.7 Hz), 140.36

1 (m), 139.64 – 138.84 (m), 138.38 (m), 136.72 (m), 128.59 (m), -6.82 (s, JSnC = 189, 197 Hz, Sn-

CH3). Elemental analysis (%) for C22H6F14Sn: Calculated: C 40.34, H 0.92; Found C 40.38, H

1.16.

6.3.2.4 Synthesis of 1-bromo-2,3-bis(pentafluorophenyl)-4,5,6,7-tetrafluoro-1-boraindene 2-11

F5C6 F4 F5C6 B 2-11 Br

In a Kontes thick-walled glass vessel, BBr3 (ca. 3 mL) was condensed into a slurry of 2-8 (528 mg, 0.806 mmol) in CH2Cl2 (3 mL) and the resulting yellow mixture was allowed to stir at room temperature for 16 hours. The solvent and excess BBr3 were removed in vacuo, and Me2SnBr2 was sublimed out of the product mixture at 60oC for one hour. The crude solid was recrystallized from hot hexanes at -30oC. The mother liquor was decanted and the solid washed with cold hexanes (2 x 2 mL). A yellow powder was obtained (440 mg, 0.738 mmol, 91.6% yield). Yellow crystals suitable for x-ray analysis were obtained from hexanes at -30oC. 19F

135 F NMR (376 MHz, CD2Cl2) δ = -123.84 (dt, J=21.6, 12.6, 1F, Ar ), -137.98 (m, 4F, o-C6F5), -

142.29 (m, 1F), -143.13 (dt, J=18.5, 13.1, 1F), -150.52 (m, 2F, ArF), -153.39 (t, J=20.8, 1F, p-

11 C6F5), -160.78 (m, 2F, m-C6F5), -161.49 (m, 2F, m-C6F5). B NMR (128 MHz, CD2Cl2) δ = 61

13 ppm (br). C NMR (101 MHz, CD2Cl2) δ, 151.83 , 150.92 (dd, J =254, 11.7 Hz), 147.48 (ddd, J

= 17.8, 13.3, 4.3 Hz), 145.17 (m), 144.91 – 144.52 (m), 144.39 – 143.74 (m), 143.21 – 142.86

(m), 142.70 (m), 142.06 (m), 141.81 – 141.05 (m), 140.72 – 140.16 (m), 138.26 (dm, J = 251

Hz), 129.70 (m), 109.98 – 108.57 (m). Elemental analysis (%) for C20BBrF14 Calculated: C

40.24; Found C 40.17. Comment: Four repeat trials found %C to be 40.17, 40.08, 40.08, 39.70, however the analysis was plagued by high %N values of 4.70, 1.29, 2.59, 2.20. The fact that the

%C values are so consistent while the %N values are not, combined with the complete absence of nitrogen in the synthesis of this compound, lead us to believe that the sample is in fact pure.

6.3.2.5 Synthesis of 1,2,3-tris(pentafluorophenyl)-4,5,6,7-tetrafluoro-1-boraindene 1-4

F5C6 F4 F5C6 B 1-4 C6F5

A solution of Zn(C6F5)2 (134 mg, 0.336 mmol) in CH2Cl2 (5 mL) was added dropwise over ~ 1 min to a stirred solution of 2-11 (400 mg, 0.671 mmol) in CH2Cl2 (5 mL). The orange-yellow solution quickly turned bright red and was allowed to stir at room temperature for 16 hours. The precipitated ZnCl2 was filtered off via syringe filter and the solvent removed in vacuo to yield 1-

4 as an orange powder (436 mg, 0.637 mmol, 95.0% yield). Red crystals suitable for x-ray

o 19 1 analysis were obtained from hexanes at -30 C. F{ H} NMR (376 MHz, CD2Cl2) δ -119.15 (m,

F 1F, Ar ), -128.11 (m, 2F, o-C6F5), -139.76 (m, 2F, o-C6F5), -141.65 (m, 2F, o-C6F5), -143.27 (m,

F F 1F, Ar ), -143.68 (dt, J = 18.8, 13.4 Hz, 1F, Ar ), -147.23 (tt, J = 20.0, 5.6 Hz, 1F, p-C6F5), -

136 F 152.20 (m, 2F, Ar and p-C6F5), -155.39 (t, J = 20.8 Hz 1F, p-C6F5), -162.27 (m, 2F, m-C6F5), -

11 13 162.47 (m, 2F, m-C6F5), -163.06 (m, 2F, m-C6F5). B NMR (128 MHz, CD2Cl2) δ 62.3 (br). C

NMR (151 MHz, CD2Cl2) δ 154.50 (m), 152.91 (m), 151.15 (m), 148.81 (m), 147.24 (m), 145.78

(m), 144.75 (m), 144.42 (m), 144.01, 143.58 (m), 143.14 (m), 142.83 (m), 141.93 (m), 140.57 (d,

J = 13.6 Hz), 138.88 (m), 137.25 (m), 130.11, 110.84 (m), 109.11, 100.43 (m). Elemental analysis (%) for C26BF19: Calculated: C 45.65; Found C 45.55.

F F m a F l b F F F k F c F F F B d F h F j e F F F F i f F F F g

19 F NMR (376 MHz, Toluene-d8) δ -115.87 (m, 1F, d), -126.29 (tt, J = 20.9, 6.5 Hz, 2F, e), -

137.65 (m, 2F, h), -139.90 (dd, J = 23.9, 7.8 Hz, 2F, k), -141.45 (m, 1F, a), -141.63 (dt, J = 19.3,

13.7 Hz, 1F, b or c), -143.20 (m, 1F, g), -148.57 (t, J = 21.2 Hz, 1F, j), -149.93 (ddd, J = 21.0,

14.3, 5.5 Hz, 1F, b or c), -151.94 (t, J = 21.1 Hz, 1F, m), -159.66 (td, J = 21.0, 7.0 Hz, 2F f), -

159.99 (td, J = 20.9, 5.9 Hz, 2F, i), -160.45 (td, J = 22.7, 7.9 Hz, 2F, l).

6.3.3 Gutmann-Beckett Experiments

Excess Lewis acid (1-1, 1-2, 1-3, 1-4) (0.01 mmol) combined with Et3PO (1.0 mg, 0.0075

31 1 mmol) in CD2Cl2 (0.6 mL). P{ H} NMR: Et3PO reference: δ 50.3. (Et3PO)B(C6F5)3 reference

137 adduct: δ 76.9. Reference Δδ 26.6. (Et3PO)-1-1 adduct: δ 78.3. Δδ 28.4. (Et3PO)-1-2 adduct: δ

79.3. Δδ 29.0. (Et3PO)-1-3 adduct: δ 77.4. Δδ 27.1. (Et3PO)-1-4 adduct: δ 81.4. Δδ 31.1.

6.4 Experimental Details for Chapter 3

6.4.1 Synthesis

6.4.1.1 Synthesis of 3-3

Ph Ph

Ph Ph Ph B H PhO 3-3

o A solution of phenol (47 mg, 0.50 mmol) in CH2Cl2 (10 mL) was added to a cold (0 C) solution of pentaphenylborole 1-1 (222 mg, 0.50 mmol) in CH2Cl2 (20 mL) via syringe over 30 minutes.

The purple solution turned pale yellow almost immediately, and the ice bath was removed. After

30 minutes the volatiles were removed in vacuo, and yellow solid was recrystallized from hot toluene and washed with cold hexanes (2 x 3 mL). A pale yellow powder was obtained (140 mg,

52% yield). Crystals suitable for x-ray analysis were grown from slow evaporation from

1 dichloromethane. H NMR (400 MHz, CD2Cl2): δ = 7.90 (m, 2H, ArH), 7.41 (m, 1H, ArH), 7.33

(m, 2H, ArH), 7.19 – 6.87 (m, 20H, ArH + C=C-H), 6.83 (m, 2H, ArH), 6.76 (m, 2H, ArH), 6.70

13 (m, 2H, ArH). C NMR (100 MHz, CD2Cl2): δ = 155.66, 152.88, 146.95, 145.64, 142.26,

139.31, 138.14, 136.70, 135.11, 131.98, 131.07, 130.80, 130.73, 130.55, 130.10, 129.08, 127.78,

127.69, 127.48, 127.40, 127.28, 127.08, 126.86, 126.48, 125.94, 123.20, 120.16. (One peaks for the carbon bonded to boron was not observed due to the quadrupolar relaxation). 11B NMR (128

138 MHz, CD2Cl2): δ = 45(br). HRMS (TOF MS EI+): Calculated for C40H31BO 538.2468, found

538.2450.

6.4.1.2 Synthesis of 3-4

F C F 5 6 F F5C6 Cl F H B F 3-4 C6F5

A 1-neck rbf was charged with a solution of 1-4 (207 mg, 0.303 mmol) in CH2Cl2 (15 mL) and equipped with a constant volume bulb (19.1 mL). The solution was cooled to -94oC and the system evacuated. HCl gas was introduced into the bulb (290 mmHg), and the valve in between the bulb and the rbf was opened. The system was allowed to stir and gradually reach room temperature overnight, resulting in a pale yellow solution. The solvent was removed in vacuo, the remaining pale yellow solids were taken up in hot hexanes and allowed to recrystallize at -

30oC to give an off-white solid (192 mg, 0.271 mmol, 89.4% yield). Crystals suitable for x-ray

o 1 19 analysis were obtained from hexanes at -30 C. H NMR (400 MHz, CD2Cl2) δ 6.76 (s, 1H). F

NMR (376 MHz, CD2Cl2) δ -128.54 (m, 2F, o-C6F5), -130.17 (ddd, J = 22.3, 12.5, 5.8 Hz, 1F,

F F Ar ), -138.19 (ddd, J = 19.3, 12.5, 6.0 Hz, 1F, Ar ), -139.11 (d, J = 20.3 Hz, 2F, o-C6F5), -

F 140.14 (m, 2F, o-C6F5), -143.02 (m, 1F, Ar ), -150.57 (td, J = 19.9, 5.8 Hz, 1F, p-C6F5), -150.78

F (m, 1F, p-C6F5), -151.35 (m, 1F, p-C6F5), -152.48 (ddd, J = 22.4, 19.7, 6.1 Hz, 1F, Ar ), -160.63

11 13 (m, 2F, m-C6F5), -161.22 (m, 4F, m-C6F5). B NMR (128 MHz, CD2Cl2) δ 61.5 (br). C NMR

(101 MHz, CD2Cl2) δ 151.1 – 150.3 (m), 149.2 , 148.4 – 148.0 (m), 147.4 (d, J = 10.3 Hz), 147.0

(m) , 146.7 (m), 145.7 (m), 144.9 (m), 144.7 – 142.7 (m), 141.5 - 140.9 (m), 140.5 - 140.1 (m),

139 139.8 – 139.0 (m), 137.4 – 136.6 (m), 129.9 (s, Cvinyl), 127.0 (s, CH), 125.0 (m) , 112.6 (m),

110.1 (m). C26HBClF19 Calculated: C 43.34, H 0.14; Found C 43.56, 0.32

6.4.1.3 Synthesis of 3-5

F C 5 6 F F5C6 F

C6F5 F H B F 3-5 H

To a solution of 3-4 (0.176 mg, 0.248 mmol) and cyclohexene (60 µL, 0.60 mmol) in CH2Cl2 (5 mL) was added Me2Si(H)Cl (0.56 mL, 6.8 mmol) and the solution was allowed to stir at room temperature for 33 hours. The volatiles were removed in vacuo, and the solids were recrystallized from pentane (< 2 mL) to give an off-white solid (132 mg, 0.172 mmol, 69.3%

1 yield). H NMR (600 MHz, C6D6) δ 6.35 (s, 1H), 1.88 – 1.59 (m, 6H), 1.42 (q, J = 12.4 Hz, 2H),

19 1.29 – 1.15 (m, 3H), F NMR (376 MHz, C6D6) δ -129.23 (d, J = 21.3 Hz, 2F, o-C6F5), -130.08

(dd, J = 24.6, 12.2 Hz, 1F, ArF), -137.77 (ddd, J = 19.4, 12.2, 5.7 Hz, 1F, ArF), -140.15 (d, J =

F 19.0 Hz, 2F, o-C6F5), -140.64 (d, J = 15.8 Hz, 2F, o-C6F5), -146.42 (tt, J = 21.2, 5.5 Hz, 1F, Ar ),

-149.46 (q, J = 21.8 Hz, 2F, ArF), -151.93 (td, J = 20.5, 4.3 Hz, 1F, ArF), -152.91 (ddd, J = 25.3,

F 20.5, 5.8 Hz, 1F, Ar ), -159.98 (td, J = 22.1, 20.4, 7.1 Hz, 2F, m-C6F5), -160.09 – -160.37 (m,

13 2F, m-C6F5), -161.05 – -161.38 (m, 2F, m-C6F5). C NMR (151 MHz, C6D6) δ 148.80 (t, J = 11.3

Hz), 147.15 (dd, J = 14.1, 8.9 Hz), 146.94 – 146.56 (m), 145.16 (dd, J = 10.9, 4.2 Hz), 144.68

(m), 143.74 – 143.22 (m), 142.96 (m), 142.38 – 141.99 (m), 141.75 (m), 141.52 – 141.03 (m),

140.74 – 140.23 (m), 140.08 (m), 138.76 (m), 137.07 (m), 130.63 (s, Cvinyl), 124.10 (s, H Cvinyl)

123.52 (m), 112.64 (m), 109.83 (m), 42.41 (s, BCH 29.08 (s, CH2), 28.22 (s, CH2), 26.59 (s,

140 CH2). Elemental analysis (%) for C32H12BF19 Calculated: C 50.03, H 1.57; Found C 50.03, H

1.78.

6.4.1.4 Synthesis of 3-6

F5C6 F F5C6 F

B F F C6F5 3-6

Cyclohexene (0.5 mL, 5 mmol) was combined with a solution of 1-4 (146 mg, 0.213 mmol) in

CH2Cl2 (0.5 mL) and stirred overnight. The volatiles were removed in vacuo and the crude solid was recrystallized from pentane (< 1 mL) at -30˚C to yield a yellow solid (102 mg, 62.4% yield).

1 H NMR (600 MHz, CDCl3) δ 1.97 (m, 2H, CH2), 1.65 (m, 2H, CH2), 1.42 – 1.31 (m, 6H, 3 x

19 F CH2). F NMR (376 MHz, CDCl3) δ -124.30 (dp, J = 23.5, 11.8 Hz, 1F, Ar ), -130.39 (m, 2F, o-

F C6F5), -135.59 (m, o-C6F5), -137.80 (ddd, J = 19.1, 12.9, 5.5 Hz, 1F, Ar ), -139.50 (td, J = 23.3,

F F 7.9 Hz, 2F, o-C6F5), -141.15 (td, J = 19.3, 11.7 Hz, 1F, Ar ), -151.36 (m, 2F, Ar ), -152.10 (m,

F 2F, Ar ), -160.00 (m, 2F, m-C6F5), -160.64 (m, 2F, m-C6F5), -161.13 (td, J = 22.2, 8.2 Hz, 2F, m-

11 13 1 C6F5). B NMR (193 MHz, CDCl3) δ 74.5 (br). C NMR (151 MHz, CDCl3) δ 152.34 (dm, JCF

= 256.9 Hz), 147.53, 147.03 (m), 146.22 (d, J = 11.4 Hz), 145.22 (m), 144.50 (m), 144.16 (m),

143.46 (m), 142.94 (m), 142.52 (m), 142.33 – 141.86 (m), 141.23 (m), 140.84 (m), 140.41 (m),

139.63 (m), 138.74 – 137.84 (m), 137.15 – 136.25 (m), 122.64 (d, J = 70.0 Hz), 113.23 (q, J =

19.1 Hz), 45.67 B-C(CH2)2, 32.83 (CH2), 24.91 (CH2), 24.25 (CH2). HRMS (TOF EI+) for

+ C32H10BF10: Calculated 766.0572 M , Found 766.0547.

141 6.4.2 Kinetics experiments for the Activation of Dihydrogen by Boroles

A J. Young NMR tube was charged with a CD2Cl2 solution (0.5 mL) containing 1-1 (0.016 M) and mesitylene (0.004 M) as an internal standard. The solution was then subjected to three freeze-pump-thaw cycles and allowed to equilibrate at a given temperature. At this time H2 gas was introduced and allowed to fill the tube for two minutes, taking care to not agitate it. The tube was carried to an NMR spectrometer in a dry ice/acetone bath and allowed to warm to the appropriate reaction temperature. Agitation of the tube was counted as t = 0. Spectra were recorded every 5-10 minutes using a delay of 45 s (~ 5 times T1 for mesitylene). For experiments at room temperature, a modified Kugelrohr apparatus was used to consistently agitate the samples in between readings. The [H2] in solution was measured from the signal at 4.61 ppm, assuming a 3:1 ratio of orthohydrogen:parahydrogen. The [3] in solution was measured from the allylic proton signals at 4.85 ppm (trans-3-1) and 4.50 ppm (cis-3-1) and from the aryl proton signals at 7.78 ppm (trans-3-1) and 7.68 ppm (cis-3-1). Activation parameters were determined by measuring rate constants at 10oC, 25oC, 31oC and 43oC, and agitation was achieved by inverting the NMR tube five times in between readings. Higher pressures of H2 were achieved

o o by introducing H2 at different temperatures: ~1 atm at 20 C, ~1.5 atm at -72 C (dry ice/acetone

o o bath), ~2 atm at -130 C (pentane/liquid N2) and ~3.8 atm at -196 C (liquid N2).

6.4.2.1 Kinetic Isotope Effects

Three J. Young NMR tubes were charged with a CD2Cl2 solution (0.5 mL) containing either 1-1 or 1-2 and toluene as an internal standard. The solutions were then subjected to three freeze- pump-thaw cycles and allowed to equilibrate to room temperature. To the first tube was added

142 H2. A 1:1 H2:D2 mixture was created by first placing both the vacuum and atmosphere lines under full (static) vacuum, then introducing H2 (300 mmHg) followed by D2 (300 mmHg) and letting the mixture equilibrate for a minimum of four hours. The J. Young tube was then opened to allow the gas mixture in. This was then repeated with the third J. Young tube, adding D2 to the vacuum line first, followed by H2. All three tubes were agitated with a modified Kugelrohr apparatus overnight. The relative concentrations of D2 addition products were calculated by taking the integrations of the benzylic resonances in 3-1 or 3-2 from the reaction with just H2 and subtracting the appropriate integrations for the reaction with 1:1 H2:D2.

6.4.3 NMR Tube Experiments

6.4.3.1 Reaction of 3-3 with DiBAl-H

A solution of 3-3 26 mg (0.050 mmol) in CD2Cl2 (~0.7 mL) was combined with DiBAl-H (50 uL, 1.0 M in hexanes) and shaken. After recording the 1H NMR spectrum, two drops of pyridine were added to the NMR tube, and the 1H NMR spectrum was recorded again.

Control: In a J. Young NMR tube, a solution of 1-1 (5 mg, 0.01 mmol) in CD2Cl2 (~0.7 mL) was

o degassed at -78 C and then charged with H2 gas (ca. 1 atm). The tube was then inverted on a modified Kugelrohr apparatus for 10 hours. Two drops of pyridine were added to the tube and the 1H NMR spectrum was recorded.

6.4.3.2 Reaction of 1-4 with H2

In a J-Young tube, a solution of 1-4 in toluene-d8 was degassed at -78˚C and then placed under an atmosphere of dihydrogen. The solution was held at 125˚C for 20 hours, and then the 19F and

1H NMR spectra were recorded.

143

6.4.3.3 Reaction of 3-4 with Me2Si(H)Cl

In an NMR tube, 3-4 (7.4 mg, 0.010 mmol) was combined with Me2Si(H)Cl (1.3 µL, 0.016) in

1 19 toluene-d8 and the mixture was allowed to stand at room temperature. H and F NMR spectra were recorded after 30 minutes, 2.5 hr, and 24 hr. 1

6.4.3.4 Thermal Decomposition of 3-5

In a J. Young tube, a solution of 3-5 in C6D6 was heated at 140˚C for 2.5 hours, during which the solution changed from pale yellow to orange.

6.4.3.5 Thermal Decomposition of 3-5 under Deuterium

A Kontes thick-walled glass vessel (115 mL) was charged with a solution of 3-5 (36 mg, 0.047 mmol) in C6D6 (0.7 mL) and the system was then subjected to three freeze-pump-thaw cycles.

The vessel was cooled to -193˚C and filled with D2. After heating the system at 140˚C for 2.5 hours, the 1H, 13C and 19F NMR spectra were recorded.

6.4.4 Hydrogenation Experiments

6.4.4.1 Hydrogenation of cyclohexene (20% loading)

A Kontes thick-walled glass vessel (30 mL) was charged with 1-4 (29 mg, 0.042 mmol) and a stock solution of cyclohexene (0.44 M) and toluene (1.3 M, internal standard) in C6D6 (0.50 mL).

After three freeze-pump-thaw cycles, the mixture was subjected to H2 (ca. 1 ATM) at -193˚C and then heated to 140˚C for 72 hours. The yield of cyclohexane (70%) was determined by 1H NMR, using a delay of 20 seconds.

144

6.4.4.2 Hydrogenation of cyclohexene (10% loading).

A Kontes thick-walled glass vessel (30 mL) was charged with 1-4 (15 mg, 0.022 mmol) and a stock solution of cyclohexene (0.44 M) and toluene (1.3 M, internal standard) in C6D6 (0.50 mL).

After three freeze-pump-thaw cycles, the mixture was subjected to H2 (ca. 1 ATM) at -193˚C and then heated to 140˚C for 48 hours. The yield of cyclohexane (54%) was determined by 1H

NMR, using a delay of 20 seconds.

6.5 Experimental Details for Chapter 4

6.5.1 Thermodynamics Experiments

1 Concentrations of Et3SiH at room temperature were determined from the CH2 and CH3 H resonances using mesitylene as an internal standard (delay set to 48 s). The concentrations of 1-

4 and mesitylene were measured during the creation of the stock solution.

6.5.1.1 Room Temperature NMR Titrations

Sixteen NMR tubes were each charged with a stock solution (0.60 mL) containing: compound 1-

4 (0.0256 M), mesitylene (0.30 M), and C6F6 (0.0043 M) in toluene-d8. To each tube was then added a different volume (in µL) of Et3SiH: 1.0, 3.0, 5.0, 10.0, 15.0, 20.0, 25.0, 30.0, 35.0, 40.0,

45.0, 50.0, 55.0, 60.0, 80.0, 100, 120. The 1H NMR spectra of each sample were then recorded at 299.8 K (4 scans, delay = 48 s). The 19F NMR spectra were recorded at 299.8 K.

145 19 Table 5: Data for the F NMR titration of 1-4 with Et3SiH at 300K

[Et3SiH]o (M) Δδ (ppm) [Et3SiH] (M) Δδ (ppm) 0.010434583 -0.1 0.417383328 -3.34 0.03130375 -0.3 0.469556244 -3.52 0.052172916 -0.53 0.52172916 -3.81 0.104345832 -1.12 0.573902075 -3.99 0.156518748 -1.62 0.626074991 -4.22 0.208691664 -1.99 0.834766655 -5.01 0.313037496 -2.72 1.043458319 -5.58 0.365210412 -3 1.252149983 -6.16

Ka = 1.13(4) Δδtot = -10.4(2)

6.5.1.2 Variable Temperature NMR Titrations

Thirteen NMR tubes were each charged with a stock solution (0.60 mL) containing: compound

1-4 (0.0256 M), mesitylene (0.30 M), and C6F6 (0.0043 M) in d8-toluene. To each tube was then added a different volume (in µL) of Et3SiH: 1.0, 2.0, 3.0, 4.0, 5.0, 10.0, 15.0, 20.0, 25.0, 30.0,

35.0, 40.0, 45.0. The 1H NMR spectra of each sample were then recorded at 298 K (4 scans, delay = 48 s). The 19F NMR spectra were recorded at the following temperatures (K): 275.2,

259.3, 243.3, 227.3, 211.3, 195.3.

146 19 Table 6: Data for the F NMR titration of 1-4 with Et3SiH at lower temperatures

[Et3SiH]o (M) Δδ (ppm) 275 K 259 K 243 K 227 K 211 K 195 K 0.009589192 -0.27 -0.59 -1.3 -2.57 -4.78 -7.94 0.019706922 -0.54 -1.1 -2.33 -4.19 -7.21 -10.16 0.029145104 -0.85 -1.75 -3.42 -5.9 -8.79 -11.38 0.038885307 -1.04 -2.08 -3.87 -6.79 -9.65 -12.38 0.048927531 -1.66 -3.22 -5.7 -8.67 -11.56 -13.2 0.106160662 -2.61 -4.86 -7.73 -10.6 -12.65 -13.57 0.152898536 -3.57 -6.07 -8.91 -11.48 -13.03 -13.61 0.204997296 -4.29 -7.01 -9.84 -12.01 -13.26 -13.69 0.251433148 -4.95 -7.67 -10.29 -12.31 -13.34 -13.72 0.30300337 -5.48 -8.27 -10.82 -12.55 -13.44 -13.76 0.347853607 -5.92 -8.7 -11.06 -12.64 -13.46 -13.79 0.4004054 -6.48 -9.08 -11.35 -12.79 -13.53 -13.81 0.446916757 -6.69 -9.39 -11.55 -12.9 -13.53 -13.82

Ka 2.7(2) 6.2(4) 15(1) 40(2) 141(17) 950(730)

Δδtot -12.4(5) -12.8(3) -13.2(2) -13.6(1) -13.7(2) -13.8(4)

6.5.2 Equilibrium Isotope Effect Measurements

Four NMR tubes were each charged with a stock solution (0.60 mL) containing: compound 1-4

(0.0256 M), mesitylene (0.30 M), and C6F6 (0.0043 M) in toluene-d8. To each tube was then added a different volume (in µL) of Et3SiD: 1, 10, 20, 30.

Table 7: Data for the determination of the Ka-D for 1-4 and Et3SiD

[Et3SiD]o Δδ (ppm) Ka-D 0.008895915 -0.1 1.122515808 0.097720276 -1.01 1.129520714 0.194167568 -1.82 1.118338508 0.309035693 -2.65 1.130384742 Average Ka-D 1.125(5)

147 6.5.3 Variable Temperature 1H NMR measurements

An NMR tube was charged with 1-4 (27 mg, 0.039 mmol), Et3SiH (5.0 µL, 0.031 mmol), and d8- toluene, then the 1H NMR spectra were recorded at the following temperatures (K): 298, 283,

273, 258, 243, 228, 213.

6.5.4 Synthesis

6.5.4.1 Synthesis of (Et3Si)2O

In air, water (20.0 µL, 1.11 mmol) was added to a slurry of Et3SiH (355 µL, 2.22 mmol) and

B(C6F5)3 (56 mg, 0.11 mmol). The vial was closed and shaken vigorously, opening occasionally to relieve pressure. Once bubbling had stopped the mixture was allowed to stand at room temperature for an hour, after which it was filtered via syringe. The clear, colourless liquid (200 mg, 73 % yield) matched the spectroscopic data reported in CDCl3 (Müller, Angew. Chem. Int.

1 Ed., 2012, 51, 2981.) H NMR (600 MHz, Tol-d8) δ 0.98 (t, J = 8.0 Hz, 18H, CH3), 0.54 (q, J =

13 29 8.0 Hz, 12H, CH2). C NMR (151 MHz, Tol-d8) δ 7.11 (CH3), 6.87 (CH2). Si NMR (119 MHz,

Tol-d8) δ 9.28.

6.5.4.2 Synthesis of 4-2

F F F PPN F5C6 F B F5C6 H C F 6 5 4-2

148 A solution of PPNCl (170 mg, 0.297 mmol) was added dropwise over 5 minutes to a cold (-

78˚C) solution of 1 (203 mg, 0.297 mmol) and Et3SiH (0.60 mL, 3.8 mmol) in CH2Cl2 (3 mL).

The now colourless solution was allowed to stir and gradually warm to room temperature over four hours, after which the volatiles were removed in vacuo. The resulting tacky solid was sonicated with hexanes for ten minutes, followed by removal of the volatiles in vacuo. The solid was then recrystallized from layered toluene/pentane, and then from CH2Cl2/pentane (both at -

19 30˚C). A white solid was obtained (271 mg, 74.7%). F NMR (376 MHz, CDCl3) δ -131.94 (d,

J = 24.9 Hz, 2F), -137.55 (dd, J = 26.0, 17.9 Hz,1F), -139.35 (d, J = 23.5 Hz, 1F), -140.61 (d, J =

23.7 Hz, 1F ), -140.90 (br, 2F), -153.51 (dd, J = 20.7, 16.2 Hz, 1F), -157.67 (t, J = 20.9 Hz, 1F),

-160.42 (t, J = 21.1 Hz, 1F), -163.37 (t, J = 20.3 Hz, 1F), -164.11 (m, 3F), -164.63 (td, J = 22.8,

1 7.6 Hz, 2F), -164.86 (t, J = 19.3 Hz, 1F), -166.28 – -166.67 (m, 2F). H NMR (400 MHz, CDCl3)

1 13 δ 7.69 – 7.54 (m, 6H), 7.52 – 7.37 (m, 24H), 3.42 (q, 1H, JHB = 90 Hz). C DEPT-Q NMR (101

MHz, CDCl3) δ 133.96 (t, JCP = 1.5 Hz, para- CH), 132.18 (m, CH), 129.66 (m, CH), 127.11 (m,

11 1 31 1 ipso-C). B NMR (128 MHz, CDCl3) δ -16.2 (d, JBH = 90 Hz). P{ H} NMR (162 MHz,

+ CDCl3 δ 21.09. HRMS (EI): [C26HBF19] calculated: 684.9868, found: 684.9853.

6.5.4.3 Synthesis of 4-3

F F F PPN F5C6 F B F5C6 Cl C6F5 4-3

A solution of PPNCl (170 mg, 0.297 mmol) in CH2Cl2 (3 mL) was added dropwise to a red solution of 1 (203 mg, 0.297 mmol) in CH2Cl2 (3 mL) over 5 minutes, after which the solution was colourless. The solution was stirred at room temperature for four hours and then the

149 volatiles were removed in vacuo. The resulting white solid was recrystallized from layered toluene/pentane at -30˚C, then from CH2Cl2/pentane at -30˚C. A white solid was obtained (339

19 mg, 90.9% yield). F NMR (376 MHz, CDCl3) δ -130.43 (dd, J = 24.5, 8.7 Hz, 2F), -136.44 (dd,

J = 24.3, 17.3 Hz, 1F), -138.61 (d, J = 23.3 Hz, 1F), -139.90 (d, J = 23.8 Hz, 1F), 152.56 (m,

1F), -156.24 (t, J = 21.0 Hz, 1F), -158.95 (t, J = 21.1 Hz, 1F), -160.98 (t, J = 20.6 Hz, 1F), -

161.14 (dd, J = 24.5, 18.1 Hz, 1F), -162.19 (t, J = 19.1 Hz, 1F), -163.37 (m, 2F), -164.19 (br,

1 2F), -165.85 (m, 2F). H NMR (400 MHz, CDCl3) δ 7.69 – 7.58 (m, 6H), 7.48 – 7.40 (m, 24H).

13 C DEPT-Q NMR (101 MHz, CDCl3) δ 133.99 (m, para- CH), 132.20 (m, CH), 129.69 (m,

11 31 1 CH), 127.10 (dd, JCP = 108.0, 1.8 Hz, ipso-C). B NMR (128 MHz, CDCl3) δ -2.63. P{ H}

+ NMR (162 MHz, CDCl3) δ 21.09 . HRMS (EI): [C26ClBF19] calculated: 718.9478, found:

718.9518.

6.5.5 Other NMR tube Experiments

6.5.5.1 Stoichiometric reaction of 1-4 with Et3SiH and PPNCl.

A solution of 1 (12 mg, 0.018 mmol) and Et3SiH (3.0 µL, 0.019 mmol) in toluene-d8 was combined with PPNCl (11 mg, 0.019 mmol) at room temperature and shaken for five minutes.

The 1H, 19F and 11B NMR spectra were then recorded.

6.5.6 Hydrosilation Experments

A solution of 1 (2.1 mg, 0.0031 mmol) in Et3SiH (50 µL, 0.31 mmol) was combined with olefin

(0.31 mmol) and shaken. The mixture was allowed to stand and small aliquots were periodically withdrawn and analyzed by 1H NMR.

150

6.5.6.1 1-triethylsilyl-3,3-dimethylbutane (4-4)

1-4 (1 mol%) + Et3SiH SiEt3

1 (90 min). H NMR (400 MHz, CDCl3) δ 1.19 – 1.10 (m, 2H, SiCH2CH2), 0.93 (t, J = 7.9 Hz, 9H,

SiCH2CH3), 0.85 (s, 9H, C(CH3)3), 0.50 (qd, J = 7.9, 0.6 Hz, 6H), 0.46 – 0.41 (m, 2H,

SiCH2CH3).

6.5.6.2 1-triethylsilyl-2,2-diphenylethane (4-5)

Ph 1-4 (1 mol%) Ph SiEt3 + Et3SiH Ph Ph

1 (90 min) H NMR (400 MHz, CDCl3) δ 7.34 – 7.23 (m, 8H, Ph), 7.18 – 7.11 (m, 2H, Ph), 4.08 (t,

J = 7.9 Hz, 1H, Ph2CHCH2), 1.42 (d, J = 7.9 Hz, 2H, CHCH2Si), 0.84 (t, J = 7.9 Hz, 9H,

SiCH2CH3), 0.35 (q, J = 7.8 Hz, 6H, SiCH2CH3)

6.5.6.3 Cyclohexyltriethylsilane (4-6)

1-4 (1 mol%) + Et3SiH SiEt3

1 (6 hrs) H NMR (400 MHz, CDCl3) δ 1.77 – 1.59 (m, 5H, Cy-H), 1.29 – 1.08 (m, 5H, Cy-H),

0.94 (t, J = 7.9 Hz, 9H, SiCH2CH3), 0.72 (m, 1H, Si-CH), 0.51 (qd, J = 7.9, 0.6 Hz, 6H,

SiCH2CH3).

151

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164

APPENDIX A: CRYSTALLOGRAPHIC DATA TABLES, ATOMIC COORDINATES AND

METRICAL DATA

Table A1. Crystal data and structure refinement for Cp2Zr(o-C6HF4)2.

Crystallographer Adrian Houghton Empirical formula C22 H12 F8 Zr Formula weight 519.54 Temperature 173(2) K Wavelength 0.71073 Å Crystal system Orthorhombic Space group P bca Unit cell dimensions a = 13.7831(3) Å a= 90°. b = 13.7152(3) Å b= 90°. c = 20.0961(5) Å g = 90°. Volume 3798.82(15) Å3 Z 8 Density (calculated) 1.817 Mg/m3 Absorption coefficient 0.662 mm-1 F(000) 2048 Crystal size 0.08 x 0.08 x 0.06 mm3 Theta range for data collection 2.03 to 27.51°. Index ranges -17<=h<=17, -17<=k<=17, -26<=l<=26 Reflections collected 15940 Independent reflections 4350 [R(int) = 0.0642] Completeness to theta = 27.51° 99.8 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9614 and 0.9490 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 4350 / 0 / 280 Goodness-of-fit on F2 1.232 Final R indices [I>2sigma(I)] R1 = 0.0593, wR2 = 0.1226 R indices (all data) R1 = 0.0909, wR2 = 0.1449 Largest diff. peak and hole 0.540 and -0.415 e.Å-3

Table A2. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for Cp2Zr(o-C6HF4)2. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ______x y z U(eq) ______C(13) 3944(4) 8700(4) 3201(3) 42(1) C(11) 2321(3) 8175(3) 3483(2) 32(1) C(12) 3276(3) 8337(3) 3643(2) 32(1) C(16) 2064(4) 8439(3) 2835(3) 40(1) C(15) 2735(4) 8800(4) 2395(3) 45(1) C(14) 3680(4) 8936(4) 2571(3) 43(1) C(7) 1449(4) 9172(4) 4767(3) 41(1) C(8) 795(4) 9358(3) 4246(3) 39(1)

165 C(9) -77(4) 8879(4) 4394(3) 41(1) C(10) 34(4) 8398(4) 4994(3) 41(1) C(6) 974(4) 8586(4) 5231(3) 41(1) C(2) 2440(4) 6284(3) 4356(3) 38(1) C(3) 2171(4) 6589(4) 4986(3) 45(1) C(4) 1209(4) 6274(4) 5097(3) 47(1) C(5) 893(4) 5789(3) 4531(3) 40(1) C(1) 1654(4) 5806(3) 4068(3) 38(1) C(17) -43(3) 7026(3) 3478(2) 33(1) C(22) 204(4) 6793(3) 2820(3) 38(1) C(18) -986(4) 6839(4) 3634(3) 40(1) C(19) -1661(4) 6471(4) 3201(3) 45(1) C(21) -460(4) 6439(3) 2378(3) 42(1) C(20) -1389(4) 6273(4) 2564(3) 42(1) F(1) 3601(2) 8170(2) 4268(2) 46(1) F(2) 4870(2) 8845(3) 3393(2) 59(1) F(3) 4329(3) 9297(2) 2144(2) 64(1) F(4) 2468(3) 9031(3) 1768(2) 70(1) F(8) -206(3) 6250(2) 1744(2) 59(1) F(7) -2036(3) 5912(2) 2128(2) 66(1) F(6) -2580(3) 6311(3) 3388(2) 68(1) F(5) -1306(2) 6965(3) 4269(2) 58(1) Zr(1) 1150(1) 7556(1) 4220(1) 26(1)

Table A3. Bond lengths [Å] and angles [°] for Cp2Zr(o-C6HF4)2. ______C(13)-F(2) 1.348(6) C(2)-C(3) 1.385(7) C(13)-C(14) 1.356(8) C(2)-C(1) 1.392(7) C(13)-C(12) 1.372(7) C(2)-Zr(1) 2.506(5) C(11)-C(12) 1.373(7) C(2)-H(2) 0.9500 C(11)-C(16) 1.397(7) C(3)-C(4) 1.412(8) C(11)-Zr(1) 2.348(5) C(3)-Zr(1) 2.473(5) C(12)-F(1) 1.353(5) C(3)-H(3) 0.9500 C(16)-C(15) 1.372(7) C(4)-C(5) 1.387(8) C(16)-H(16) 0.9500 C(4)-Zr(1) 2.492(5) C(15)-F(4) 1.351(6) C(4)-H(4) 0.9500 C(15)-C(14) 1.363(8) C(5)-C(1) 1.402(7) C(14)-F(3) 1.336(6) C(5)-Zr(1) 2.527(5) C(7)-C(6) 1.395(7) C(5)-H(5) 0.9500 C(7)-C(8) 1.405(8) C(1)-Zr(1) 2.517(4) C(7)-Zr(1) 2.509(5) C(1)-H(1) 0.9500 C(7)-H(7) 0.9500 C(17)-C(18) 1.363(7) C(8)-C(9) 1.401(7) C(17)-C(22) 1.401(7) C(8)-Zr(1) 2.519(4) C(17)-Zr(1) 2.336(5) C(8)-H(8) 0.9500 C(22)-C(21) 1.364(7) C(9)-C(10) 1.384(7) C(22)-H(22) 0.9500 C(9)-Zr(1) 2.505(5) C(18)-F(5) 1.361(6) C(9)-H(9) 0.9500 C(18)-C(19) 1.371(7) C(10)-C(6) 1.404(7) C(19)-F(6) 1.339(6) C(10)-Zr(1) 2.475(5) C(19)-C(20) 1.360(8) C(10)-H(10) 0.9500 C(21)-F(8) 1.346(6) C(6)-Zr(1) 2.487(5) C(21)-C(20) 1.353(8) C(6)-H(6) 0.9500 C(20)-F(7) 1.345(6)

F(2)-C(13)-C(14) 119.1(5) F(2)-C(13)-C(12) 120.2(5)

166 C(14)-C(13)-C(12) 120.7(5) C(4)-C(3)-H(3) 126.1 C(12)-C(11)-C(16) 114.7(4) Zr(1)-C(3)-H(3) 116.5 C(12)-C(11)-Zr(1) 124.8(4) C(5)-C(4)-C(3) 108.1(5) C(16)-C(11)-Zr(1) 120.5(4) C(5)-C(4)-Zr(1) 75.3(3) F(1)-C(12)-C(13) 116.1(5) C(3)-C(4)-Zr(1) 72.7(3) F(1)-C(12)-C(11) 120.4(4) C(5)-C(4)-H(4) 125.9 C(13)-C(12)-C(11) 123.4(5) C(3)-C(4)-H(4) 125.9 C(15)-C(16)-C(11) 121.6(5) Zr(1)-C(4)-H(4) 117.9 C(15)-C(16)-H(16) 119.2 C(4)-C(5)-C(1) 107.6(5) C(11)-C(16)-H(16) 119.2 C(4)-C(5)-Zr(1) 72.6(3) F(4)-C(15)-C(14) 118.1(5) C(1)-C(5)-Zr(1) 73.5(3) F(4)-C(15)-C(16) 120.2(5) C(4)-C(5)-H(5) 126.2 C(14)-C(15)-C(16) 121.7(5) C(1)-C(5)-H(5) 126.2 F(3)-C(14)-C(13) 120.6(5) Zr(1)-C(5)-H(5) 119.6 F(3)-C(14)-C(15) 121.6(5) C(2)-C(1)-C(5) 108.3(5) C(13)-C(14)-C(15) 117.8(5) C(2)-C(1)-Zr(1) 73.5(3) C(6)-C(7)-C(8) 107.6(5) C(5)-C(1)-Zr(1) 74.3(3) C(6)-C(7)-Zr(1) 72.9(3) C(2)-C(1)-H(1) 125.9 C(8)-C(7)-Zr(1) 74.2(3) C(5)-C(1)-H(1) 125.9 C(6)-C(7)-H(7) 126.2 Zr(1)-C(1)-H(1) 118.3 C(8)-C(7)-H(7) 126.2 C(18)-C(17)-C(22) 114.0(5) Zr(1)-C(7)-H(7) 118.7 C(18)-C(17)-Zr(1) 125.7(4) C(9)-C(8)-C(7) 107.9(5) C(22)-C(17)-Zr(1) 120.2(4) C(9)-C(8)-Zr(1) 73.2(3) C(21)-C(22)-C(17) 122.2(5) C(7)-C(8)-Zr(1) 73.4(3) C(21)-C(22)-H(22) 118.9 C(9)-C(8)-H(8) 126.1 C(17)-C(22)-H(22) 118.9 C(7)-C(8)-H(8) 126.1 F(5)-C(18)-C(17) 120.1(5) Zr(1)-C(8)-H(8) 119.2 F(5)-C(18)-C(19) 115.0(5) C(10)-C(9)-C(8) 108.3(5) C(17)-C(18)-C(19) 124.7(5) C(10)-C(9)-Zr(1) 72.7(3) F(6)-C(19)-C(20) 119.5(5) C(8)-C(9)-Zr(1) 74.4(3) F(6)-C(19)-C(18) 121.6(5) C(10)-C(9)-H(9) 125.9 C(20)-C(19)-C(18) 118.9(5) C(8)-C(9)-H(9) 125.9 F(8)-C(21)-C(20) 118.4(5) Zr(1)-C(9)-H(9) 119.0 F(8)-C(21)-C(22) 120.7(5) C(9)-C(10)-C(6) 108.1(5) C(20)-C(21)-C(22) 120.9(5) C(9)-C(10)-Zr(1) 75.1(3) F(7)-C(20)-C(21) 120.6(5) C(6)-C(10)-Zr(1) 74.0(3) F(7)-C(20)-C(19) 120.2(5) C(9)-C(10)-H(10) 126.0 C(21)-C(20)-C(19) 119.2(5) C(6)-C(10)-H(10) 126.0 C(17)-Zr(1)-C(11) 101.19(17) Zr(1)-C(10)-H(10) 117.0 C(17)-Zr(1)-C(3) 129.14(17) C(7)-C(6)-C(10) 108.2(5) C(11)-Zr(1)-C(3) 101.29(19) C(7)-C(6)-Zr(1) 74.7(3) C(17)-Zr(1)-C(10) 96.28(17) C(10)-C(6)-Zr(1) 73.1(3) C(11)-Zr(1)-C(10) 130.91(16) C(7)-C(6)-H(6) 125.9 C(3)-Zr(1)-C(10) 102.2(2) C(10)-C(6)-H(6) 125.9 C(17)-Zr(1)-C(6) 129.05(18) Zr(1)-C(6)-H(6) 118.3 C(11)-Zr(1)-C(6) 112.13(17) C(3)-C(2)-C(1) 108.3(5) C(3)-Zr(1)-C(6) 81.42(18) C(3)-C(2)-Zr(1) 72.5(3) C(10)-Zr(1)-C(6) 32.88(17) C(1)-C(2)-Zr(1) 74.3(3) C(17)-Zr(1)-C(4) 104.76(18) C(3)-C(2)-H(2) 125.9 C(11)-Zr(1)-C(4) 132.76(18) C(1)-C(2)-H(2) 125.9 C(3)-Zr(1)-C(4) 33.05(18) Zr(1)-C(2)-H(2) 119.1 C(10)-Zr(1)-C(4) 84.51(19) C(2)-C(3)-C(4) 107.7(5) C(6)-Zr(1)-C(4) 79.95(18) C(2)-C(3)-Zr(1) 75.2(3) C(17)-Zr(1)-C(9) 80.76(17) C(4)-C(3)-Zr(1) 74.2(3) C(11)-Zr(1)-C(9) 106.85(17) C(2)-C(3)-H(3) 126.1 C(3)-Zr(1)-C(9) 133.30(19) 167 C(10)-Zr(1)-C(9) 32.27(17) C(9)-Zr(1)-C(1) 153.39(18) C(6)-Zr(1)-C(9) 53.76(18) C(2)-Zr(1)-C(1) 32.18(16) C(4)-Zr(1)-C(9) 115.75(19) C(7)-Zr(1)-C(1) 148.24(18) C(17)-Zr(1)-C(2) 110.64(16) C(17)-Zr(1)-C(8) 100.48(17) C(11)-Zr(1)-C(2) 80.38(16) C(11)-Zr(1)-C(8) 77.98(16) C(3)-Zr(1)-C(2) 32.29(17) C(3)-Zr(1)-C(8) 128.60(18) C(10)-Zr(1)-C(2) 134.21(18) C(10)-Zr(1)-C(8) 53.75(17) C(6)-Zr(1)-C(2) 112.03(17) C(6)-Zr(1)-C(8) 53.65(17) C(4)-Zr(1)-C(2) 53.73(18) C(4)-Zr(1)-C(8) 133.15(18) C(9)-Zr(1)-C(2) 165.48(17) C(9)-Zr(1)-C(8) 32.39(17) C(17)-Zr(1)-C(7) 132.12(17) C(2)-Zr(1)-C(8) 144.90(18) C(11)-Zr(1)-C(7) 81.03(17) C(7)-Zr(1)-C(8) 32.46(17) C(3)-Zr(1)-C(7) 96.17(18) C(1)-Zr(1)-C(8) 172.40(17) C(10)-Zr(1)-C(7) 54.11(17) C(17)-Zr(1)-C(5) 76.18(17) C(6)-Zr(1)-C(7) 32.41(17) C(11)-Zr(1)-C(5) 126.79(16) C(4)-Zr(1)-C(7) 107.93(19) C(3)-Zr(1)-C(5) 53.90(18) C(9)-Zr(1)-C(7) 53.81(18) C(10)-Zr(1)-C(5) 101.81(17) C(2)-Zr(1)-C(7) 116.78(17) C(6)-Zr(1)-C(5) 109.17(18) C(17)-Zr(1)-C(1) 79.64(16) C(4)-Zr(1)-C(5) 32.08(18) C(11)-Zr(1)-C(1) 94.51(16) C(9)-Zr(1)-C(5) 124.44(18) C(3)-Zr(1)-C(1) 53.61(17) C(2)-Zr(1)-C(5) 53.49(17) C(10)-Zr(1)-C(1) 133.86(17) C(7)-Zr(1)-C(5) 139.59(19) C(6)-Zr(1)-C(1) 131.86(17) C(1)-Zr(1)-C(5) 32.28(17) C(4)-Zr(1)-C(1) 53.41(18) C(8)-Zr(1)-C(5) 155.23(18) ______Symmetry transformations used to generate equivalent atoms:

Table A4: Crystal data and structure refinement for 1-3C6F5 Crystallographer Adrian Houghton Chemical formula C26 H9 B F10 Molecular weight 522.14 Temperature 150(2) Wavelength 0.71073 Crystal system ; space group orthorhombic ; Pbca a = 7.2260(6) Å ; α = 90.00 ° Unit cell dimentions b = 20.6930(2) Å ; β = 90.00 ° c = 28.1810(7) Å ; γ = 90.00 ° Volume 4213.8(4) Å³ Z, Calculated density 8, 1.646 g/cm³ Absorption coefficient 0.157 1/mm F(000) 2080 Theta range for data collection 1.97° to 27.46° Limiting indices -9 <= h <= 9 ; -26 <= k <= 26 ; -32 <= l <= 36 Reflexion collected / unique 15470 / 4777 [R(int) = 0.0678] Completness to theta max 99.0 % Refinement method Full-matrix least-square on F² Data / restraints / parameters 4777 / 0 / 334 Goodness of fit on F² 1.248 Final R indices [I>2sigma(I)] R1 = 0.0762 ; wR2 = 0.1778 Final R indices [all data] R1 = 0.1127 ; wR2 = 0.2074 Absolute structure parameter Largest diff peak and hole 0.385 and -0.332 e/Å³

168 Table A5: Atomic coordinates (x 104) and equivalent isotropic displacements parameters (Å2 x 103) for 1- 3C6F5. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. Label x y z U(eq) B1 1087(5) 3421.7(1.9) 1840.1(1.3) 28.0(8) C1 1641(5) 3898.9(1.6) 1423.8(1.1) 27.0(7) C10 444(6) 2291.5(1.6) 2160.0(1.3) 35.6(8) C11 -497(7) 1716.5(1.9) 2156.6(1.6) 49.3(1.1) C12 -1778(7) 1593(2) 1813.3(1.7) 56.6(1.3) C13 -2130(6) 2042(2) 1464.5(1.6) 51.6(1.1) C14 -1157(5) 2613.9(1.8) 1457.6(1.3) 37.3(9) C15 1337(5) 3803.7(1.6) 908.9(1.1) 28.9(7) C16 164(5) 4189.3(1.7) 647.3(1.2) 32.0(8) C17 -176(5) 4079(2) 175.9(1.3) 38.8(9) C18 663(6) 3566(2) -50.1(1.3) 43(1) C19 1832(6) 3173.3(1.8) 198.9(1.4) 41.0(9) C2 2380(5) 4436.8(1.6) 1617.0(1.1) 26.2(7) C20 2167(6) 3296.7(1.7) 669.5(1.3) 36.1(8) C21 3036(5) 5002.3(1.6) 1346.4(1.2) 27.2(7) C22 4311(5) 4955.7(1.9) 978.6(1.2) 34.1(8) C23 4851(6) 5482(2) 715.6(1.3) 40.0(9) C24 4116(6) 6078.4(1.9) 812.7(1.4) 42.6(1.0) C25 2874(6) 6149.1(1.7) 1172.1(1.4) 38.2(9) C26 2358(5) 5616.8(1.7) 1433.0(1.2) 31.8(8) C3 2421(4) 4399.4(1.5) 2145.2(1.1) 25.1(7) C4 3009(5) 4852.2(1.6) 2468.6(1.2) 29.8(7) C5 2845(5) 4711.7(1.7) 2949.7(1.2) 32.1(8) C6 2107(5) 4136.1(1.8) 3100.8(1.2) 33.2(8) C7 1499(5) 3680.8(1.7) 2770.8(1.2) 28.7(7) C8 1665(5) 3801.8(1.6) 2294.8(1.2) 26.9(7) C9 133(5) 2761.0(1.6) 1812.8(1.2) 29.0(7) F1 3359(4) 2918.8(1.1) 904.5(8) 48.9(6) F10 1078(3) 5708(1) 1772.3(8) 41.1(5) F2 2656(4) 2676.3(1.1) -19.3(8) 57.4(7) F3 336(4) 3456.9(1.5) -508.2(8) 65.1(8) F4 -1329(4) 4457.6(1.3) -71.4(8) 58.4(7) F5 -703(3) 4687.4(1.1) 856.0(7) 40.6(5) F6 5047(3) 4381(1) 867.6(7) 38.4(5) F7 6083(4) 5413.6(1.3) 363.3(8) 54.8(7) F8 4611(4) 6585.8(1.2) 548.6(9) 63.6(8) F9 2133(4) 6722.2(1.0) 1270.0(9) 53.4(7)

Table A6: Bond lengths (Å) and angles (˚)for 1-3C6F. Bond Length (Å) C13 - C14 1.376(5) B1 - C1 1.585(5) C13 - H13 0.9500 B1 - C8 1.561(5) C14 - H14 0.9500 B1 - C9 1.533(5) C15 - C16 1.377(5) C1 - C15 1.481(4) C15 - C20 1.384(5) C1 - C2 1.349(5) C16 - C17 1.371(5) C10 - C11 1.370(5) C16 - F5 1.342(4) C10 - H10 0.9500 C17 - C18 1.378(6) C11 - C12 1.363(7) C17 - F4 1.340(4) C11 - H11 0.9500 C18 - C19 1.366(6) C12 - C13 1.377(7) C18 - F3 1.332(4) C12 - H12 0.9500 C19 - C20 1.372(5)

169 C19 - F2 1.338(4) C26 - F10 1.344(4) C2 - C21 1.475(4) C3 - C4 1.374(5) C2 - C3 1.491(4) C3 - C8 1.416(5) C20 - F1 1.339(4) C4 - C5 1.392(5) C21 - C22 1.390(5) C4 - H4 0.9500 C21 - C26 1.384(5) C5 - C6 1.373(5) C22 - C23 1.373(5) C5 - H5 0.9500 C22 - F6 1.340(4) C6 - C7 1.395(5) C23 - C24 1.372(6) C6 - H6 0.9500 C23 - F7 1.341(5) C7 - C8 1.370(5) C24 - C25 1.361(6) C7 - H7 0.9500 C24 - F8 1.336(4) C9 - C10 1.397(5) C25 - C26 1.376(5) C9 - C14 1.401(5) C25 - F9 1.330(4)

Atoms Angle (°) C3 - C8 - B1 107.4(3) C1 - C2 - C21 125.0(3) C4 - C3 - C2 129.3(3) C1 - C2 - C3 111.6(3) C4 - C3 - C8 121.1(3) C10 - C11 - H11 119.8 C4 - C5 - H5 119.4 C10 - C9 - B1 120.9(3) C5 - C4 - H4 120.7 C10 - C9 - C14 117.1(3) C5 - C6 - C7 120.1(3) C11 - C10 - C9 121.3(4) C5 - C6 - H6 120.0 C11 - C10 - H10 119.4 C6 - C5 - C4 121.1(3) C11 - C12 - C13 120.4(4) C6 - C5 - H5 119.4 C11 - C12 - H12 119.8 C6 - C7 - H7 119.9 C12 - C11 - C10 120.3(4) C7 - C6 - H6 120.0 C12 - C11 - H11 119.9 C7 - C8 - B1 133.5(3) C12 - C13 - C14 119.8(4) C7 - C8 - C3 119.0(3) C12 - C13 - H13 120.1 C8 - B1 - C1 103.1(3) C13 - C12 - H12 119.8 C8 - C3 - C2 109.6(3) C13 - C14 - C9 121.1(4) C8 - C7 - C6 120.1(3) C13 - C14 - H14 119.5 C8 - C7 - H7 119.9 C14 - C13 - H13 120.1 C9 - B1 - C1 129.2(3) C14 - C9 - B1 121.9(3) C9 - B1 - C8 127.7(3) C15 - C1 - B1 127.2(3) C9 - C10 - H10 119.4 C16 - C15 - C1 122.6(3) C9 - C14 - H14 119.5 C16 - C15 - C20 116.4(3) F1 - C20 - C15 118.7(3) C16 - C17 - C18 119.9(4) F1 - C20 - C19 118.9(3) C17 - C16 - C15 122.2(3) F10 - C26 - C21 119.9(3) C18 - C19 - C20 119.7(4) F10 - C26 - C25 117.0(3) C19 - C18 - C17 119.5(3) F2 - C19 - C18 119.8(4) C19 - C20 - C15 122.4(4) F2 - C19 - C20 120.6(4) C2 - C1 - B1 108.4(3) F3 - C18 - C17 120.0(4) C2 - C1 - C15 124.3(3) F3 - C18 - C19 120.5(4) C20 - C15 - C1 120.9(3) F4 - C17 - C16 121.2(4) C21 - C2 - C3 123.4(3) F4 - C17 - C18 118.9(3) C22 - C21 - C2 122.9(3) F5 - C16 - C15 119.9(3) C22 - C23 - C24 119.7(4) F5 - C16 - C17 118.0(3) C23 - C22 - C21 122.4(4) F6 - C22 - C21 119.9(3) C24 - C25 - C26 119.4(4) F6 - C22 - C23 117.7(3) C25 - C24 - C23 120.0(3) F7 - C23 - C22 120.3(4) C25 - C26 - C21 123.0(4) F7 - C23 - C24 120.0(3) C26 - C21 - C2 121.6(3) F8 - C24 - C23 119.5(4) C26 - C21 - C22 115.5(3) F8 - C24 - C25 120.5(4) C3 - C4 - C5 118.5(3) F9 - C25 - C24 121.0(3) C3 - C4 - H4 120.7 F9 - C25 - C26 119.6(4) 170

Table A7. Crystal data and structure refinement for 1-4.

Crystallographer Adrian Houghton Empirical formula C26 B F19 Formula weight 684.07 Temperature 173(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group P 21/c Unit cell dimensions a = 11.0400(4) Å a= 90°. b = 8.8720(3) Å b= 101.6140(10)°. c = 23.9650(9) Å g = 90°. Volume 2299.24(14) Å3 Z 4 Density (calculated) 1.976 Mg/m3 Absorption coefficient 0.223 mm-1 F(000) 1328 Crystal size 0.08 x 0.08 x 0.06 mm3 Theta range for data collection 1.74 to 27.37°. Index ranges -14<=h<=14, -11<=k<=11, -30<=l<=30 Reflections collected 9564 Independent reflections 5161 [R(int) = 0.0377] Completeness to theta = 27.37° 98.7 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.8514 and 0.5561 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5161 / 0 / 415 Goodness-of-fit on F2 1.164 Final R indices [I>2sigma(I)] R1 = 0.0653, wR2 = 0.1727 R indices (all data) R1 = 0.0876, wR2 = 0.2005 Largest diff. peak and hole 0.366 and -0.433 e.Å-3

Table A8. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 1-4. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ______x y z U(eq) ______F(17) 9993(2) -2859(3) 1066(1) 34(1) F(1) 5087(2) -4021(3) 557(1) 37(1) F(5) 1080(2) -177(3) 1462(1) 34(1) F(11) 6450(2) 3497(3) 2924(1) 40(1) F(15) 7006(2) -1319(3) 2079(1) 36(1) F(4) 863(2) -769(3) 362(1) 34(1) F(19) 6092(2) -1407(3) 72(1) 34(1) F(7) 287(2) 4769(3) 1922(1) 44(1) F(16) 9314(2) -2239(3) 2067(1) 37(1) F(18) 8405(2) -2311(3) 70(1) 34(1) F(3) 839(2) -3493(3) -123(1) 43(1) F(9) 3781(2) 3741(3) 1182(1) 38(1) F(2) 2944(2) -5110(3) -7(1) 41(1)

171 F(14) 6428(2) 2066(3) 731(1) 42(1) F(6) -380(2) 1822(3) 1822(1) 41(1) F(12) 7827(3) 5111(3) 2321(1) 47(1) F(10) 5001(2) 1245(3) 2427(1) 39(1) F(8) 2367(2) 5709(3) 1591(1) 44(1) F(13) 7832(3) 4349(3) 1224(1) 49(1) C(25) 8057(3) -2078(4) 563(2) 26(1) C(24) 8879(3) -2318(4) 1069(2) 27(1) C(1) 4810(3) 428(4) 1267(2) 24(1) C(2) 5182(3) -870(4) 1057(2) 24(1) C(7) 1926(3) -1537(4) 439(2) 28(1) C(10) 2772(3) 3223(4) 1348(2) 28(1) C(17) 6434(4) 3157(4) 2382(2) 29(1) C(21) 6470(3) -1341(4) 1073(2) 24(1) C(26) 6878(3) -1606(4) 571(2) 26(1) C(4) 4072(3) -3169(4) 529(2) 26(1) C(20) 6423(4) 2403(5) 1276(2) 29(1) C(9) 2497(3) 1686(4) 1305(2) 26(1) C(15) 5667(3) 1589(4) 1564(2) 25(1) C(8) 3002(3) -951(4) 747(2) 24(1) C(6) 1890(3) -2945(5) 182(2) 30(1) C(11) 2048(4) 4253(4) 1548(2) 32(1) B(1) 3356(4) 496(5) 1108(2) 26(1) C(13) 652(4) 2287(5) 1667(2) 31(1) C(18) 7143(4) 3961(5) 2079(2) 34(1) C(3) 4108(3) -1772(4) 766(2) 24(1) C(16) 5701(3) 2000(4) 2124(2) 27(1) C(5) 2948(4) -3756(5) 235(2) 31(1) C(14) 1401(3) 1279(4) 1470(2) 28(1) C(23) 8514(3) -2032(4) 1576(2) 28(1) C(12) 980(4) 3782(5) 1713(2) 33(1) C(19) 7140(4) 3575(5) 1522(2) 34(1) C(22) 7336(4) -1546(4) 1577(2) 27(1)

Table A9. Bond lengths [Å] and angles [°] for 1-4. ______F(17)-C(24) 1.321(4) C(25)-C(26) 1.372(5) F(1)-C(4) 1.342(4) C(25)-C(24) 1.377(5) F(5)-C(14) 1.339(4) C(24)-C(23) 1.379(6) F(11)-C(17) 1.330(4) C(1)-C(2) 1.353(5) F(15)-C(22) 1.340(4) C(1)-C(15) 1.480(5) F(4)-C(7) 1.337(4) C(1)-B(1) 1.575(5) F(19)-C(26) 1.341(4) C(2)-C(21) 1.476(5) F(7)-C(12) 1.326(5) C(2)-C(3) 1.483(5) F(16)-C(23) 1.335(4) C(7)-C(8) 1.369(5) F(18)-C(25) 1.330(4) C(7)-C(6) 1.390(6) F(3)-C(6) 1.332(4) C(10)-C(11) 1.362(6) F(9)-C(10) 1.338(4) C(10)-C(9) 1.396(5) F(2)-C(5) 1.333(5) C(17)-C(18) 1.371(6) F(14)-C(20) 1.340(4) C(17)-C(16) 1.374(5) F(6)-C(13) 1.333(5) C(21)-C(26) 1.387(5) F(12)-C(18) 1.331(5) C(21)-C(22) 1.392(5) F(10)-C(16) 1.342(4) C(4)-C(3) 1.361(5) F(8)-C(11) 1.337(5) C(4)-C(5) 1.398(5) F(13)-C(19) 1.336(5) C(20)-C(19) 1.367(6)

172 C(20)-C(15) 1.388(5) C(6)-C(5) 1.356(6) C(9)-C(14) 1.394(5) C(11)-C(12) 1.382(6) C(9)-B(1) 1.555(6) C(13)-C(14) 1.365(6) C(15)-C(16) 1.385(5) C(13)-C(12) 1.373(6) C(8)-C(3) 1.415(5) C(18)-C(19) 1.376(6) C(8)-B(1) 1.553(6) C(23)-C(22) 1.371(5)

F(18)-C(25)-C(26) 120.3(3) C(3)-C(8)-B(1) 106.8(3) F(18)-C(25)-C(24) 120.1(3) F(3)-C(6)-C(5) 119.8(4) C(26)-C(25)-C(24) 119.6(3) F(3)-C(6)-C(7) 120.9(4) F(17)-C(24)-C(25) 120.1(3) C(5)-C(6)-C(7) 119.3(3) F(17)-C(24)-C(23) 120.5(3) F(8)-C(11)-C(10) 120.7(4) C(25)-C(24)-C(23) 119.3(3) F(8)-C(11)-C(12) 119.8(4) C(2)-C(1)-C(15) 123.9(3) C(10)-C(11)-C(12) 119.5(4) C(2)-C(1)-B(1) 108.3(3) C(8)-B(1)-C(9) 129.1(3) C(15)-C(1)-B(1) 127.7(3) C(8)-B(1)-C(1) 103.5(3) C(1)-C(2)-C(21) 126.5(3) C(9)-B(1)-C(1) 127.3(3) C(1)-C(2)-C(3) 111.1(3) F(6)-C(13)-C(14) 120.3(4) C(21)-C(2)-C(3) 122.3(3) F(6)-C(13)-C(12) 120.1(4) F(4)-C(7)-C(8) 121.5(4) C(14)-C(13)-C(12) 119.5(4) F(4)-C(7)-C(6) 116.8(3) F(12)-C(18)-C(17) 120.1(4) C(8)-C(7)-C(6) 121.6(4) F(12)-C(18)-C(19) 120.3(4) F(9)-C(10)-C(11) 117.2(4) C(17)-C(18)-C(19) 119.6(4) F(9)-C(10)-C(9) 119.7(3) C(4)-C(3)-C(8) 120.2(3) C(11)-C(10)-C(9) 123.2(4) C(4)-C(3)-C(2) 129.9(3) F(11)-C(17)-C(18) 120.1(4) C(8)-C(3)-C(2) 109.9(3) F(11)-C(17)-C(16) 120.0(4) F(10)-C(16)-C(17) 118.7(4) C(18)-C(17)-C(16) 119.8(4) F(10)-C(16)-C(15) 119.2(3) C(26)-C(21)-C(22) 116.4(3) C(17)-C(16)-C(15) 122.1(4) C(26)-C(21)-C(2) 120.2(3) F(2)-C(5)-C(6) 120.7(4) C(22)-C(21)-C(2) 123.4(3) F(2)-C(5)-C(4) 118.7(4) F(19)-C(26)-C(25) 118.2(3) C(6)-C(5)-C(4) 120.6(4) F(19)-C(26)-C(21) 119.2(3) F(5)-C(14)-C(13) 117.3(3) C(25)-C(26)-C(21) 122.6(3) F(5)-C(14)-C(9) 119.3(3) F(1)-C(4)-C(3) 122.5(3) C(13)-C(14)-C(9) 123.3(4) F(1)-C(4)-C(5) 117.6(3) F(16)-C(23)-C(22) 120.1(4) C(3)-C(4)-C(5) 119.9(4) F(16)-C(23)-C(24) 119.6(3) F(14)-C(20)-C(19) 118.4(4) C(22)-C(23)-C(24) 120.3(3) F(14)-C(20)-C(15) 119.3(3) F(7)-C(12)-C(13) 120.4(4) C(19)-C(20)-C(15) 122.3(4) F(7)-C(12)-C(11) 119.9(4) C(14)-C(9)-C(10) 114.8(3) C(13)-C(12)-C(11) 119.7(4) C(14)-C(9)-B(1) 121.8(3) F(13)-C(19)-C(20) 120.2(4) C(10)-C(9)-B(1) 123.3(3) F(13)-C(19)-C(18) 120.0(4) C(16)-C(15)-C(20) 116.3(3) C(20)-C(19)-C(18) 119.8(4) C(16)-C(15)-C(1) 122.6(3) F(15)-C(22)-C(23) 118.5(3) C(20)-C(15)-C(1) 120.9(3) F(15)-C(22)-C(21) 119.7(3) C(7)-C(8)-C(3) 118.1(3) C(23)-C(22)-C(21) 121.7(3) C(7)-C(8)-B(1) 135.1(4) ______Symmetry transformations used to generate equivalent atoms:

Table A10. Crystal data and structure refinement for 2-7CH3.

Crystallographer Adrian Houghton Empirical formula C24 H24 Sn

173 Formula weight 431.12 Temperature 173(2) K Wavelength 0.71073 Å Crystal system Orthorhombic Space group P 21 21 21 Unit cell dimensions a = 5.89010(10) Å a= 90°. b = 15.2272(5) Å b= 90°. c = 21.6291(7) Å g = 90°. Volume 1939.91(10) Å3 Z 4 Density (calculated) 1.476 Mg/m3 Absorption coefficient 1.320 mm-1 F(000) 872 Crystal size 0.08 x 0.07 x 0.06 mm3 Theta range for data collection 1.64 to 27.48°. Index ranges -7<=h<=7, -19<=k<=19, -27<=l<=28 Reflections collected 4416 Independent reflections 4416 [R(int) = 0.0000] Completeness to theta = 27.48° 99.7 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9250 and 0.9018 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 4416 / 0 / 230 Goodness-of-fit on F2 1.265 Final R indices [I>2sigma(I)] R1 = 0.0386, wR2 = 0.1029 R indices (all data) R1 = 0.0461, wR2 = 0.1258 Absolute structure parameter 0.02(5) Largest diff. peak and hole 0.547 and -0.483 e.Å-3

Table A11. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 2- ij 7CH3. U(eq) is defined as one third of the trace of the orthogonalized U tensor. ______x y z U(eq) ______Sn(1) 2515(1) 2110(1) 1950(1) 25(1) C(2) 3850(8) 481(4) 1361(2) 22(1) C(24) 278(11) 2372(5) 2698(3) 37(1) C(10) 3830(10) -1154(4) 1361(3) 29(1) C(5) -361(10) 2100(4) 674(3) 31(1) C(16) 5841(9) 577(3) 2394(3) 24(1) C(1) 4286(9) 879(4) 1908(2) 24(1) C(12) 6630(11) -2000(4) 791(3) 31(1) C(21) 5301(10) 739(4) 3012(3) 27(1) C(3) 2251(11) 920(3) 910(2) 24(1) C(8) 1861(9) 565(4) 322(3) 30(1) C(7) 377(10) 984(4) -79(3) 31(1) C(6) -751(10) 1742(4) 94(3) 32(1) C(14) 6676(10) -418(4) 778(3) 33(1) C(9) 4809(9) -380(4) 1168(3) 26(1) C(13) 7591(18) -1224(4) 602(3) 36(1) C(17) 7932(9) 168(4) 2286(3) 29(1) C(15) 7631(18) -2872(4) 608(3) 43(2) C(18) 9351(10) -79(4) 2761(3) 32(1) 174 C(4) 1149(9) 1708(4) 1081(2) 25(1) C(20) 6725(10) 491(4) 3490(3) 29(1) C(19) 8752(10) 74(4) 3374(3) 28(1) C(23) 4859(11) 3170(4) 1844(3) 36(1) C(11) 4751(12) -1962(4) 1173(3) 35(1) C(22) 10265(12) -218(5) 3896(3) 41(2)

Table A12. Bond lengths [Å] and angles [°] for 2-7CH3. ______Sn(1)-C(24) 2.125(6) C(8)-C(7) 1.388(8) Sn(1)-C(4) 2.134(6) C(8)-H(8) 0.9500 Sn(1)-C(23) 2.136(6) C(7)-C(6) 1.383(9) Sn(1)-C(1) 2.147(5) C(7)-H(7) 0.9500 C(2)-C(1) 1.355(8) C(6)-H(6) 0.9500 C(2)-C(9) 1.487(7) C(14)-C(9) 1.387(8) C(2)-C(3) 1.512(7) C(14)-C(13) 1.394(9) C(24)-H(24A) 0.9800 C(14)-H(14) 0.9500 C(24)-H(24B) 0.9800 C(13)-H(13) 0.9500 C(24)-H(24C) 0.9800 C(17)-C(18) 1.376(8) C(10)-C(9) 1.378(8) C(17)-H(17) 0.9500 C(10)-C(11) 1.405(8) C(15)-H(15A) 0.9800 C(10)-H(10) 0.9500 C(15)-H(15B) 0.9800 C(5)-C(4) 1.386(8) C(15)-H(15C) 0.9800 C(5)-C(6) 1.387(9) C(18)-C(19) 1.393(9) C(5)-H(5) 0.9500 C(18)-H(18) 0.9500 C(16)-C(21) 1.395(8) C(20)-C(19) 1.375(8) C(16)-C(17) 1.400(7) C(20)-H(20) 0.9500 C(16)-C(1) 1.468(8) C(19)-C(22) 1.504(8) C(12)-C(13) 1.373(9) C(23)-H(23A) 0.9800 C(12)-C(11) 1.381(9) C(23)-H(23B) 0.9800 C(12)-C(15) 1.507(8) C(23)-H(23C) 0.9800 C(21)-C(20) 1.383(8) C(11)-H(11) 0.9500 C(21)-H(21) 0.9500 C(22)-H(22A) 0.9800 C(3)-C(8) 1.399(7) C(22)-H(22B) 0.9800 C(3)-C(4) 1.414(8) C(22)-H(22C) 0.9800

C(24)-Sn(1)-C(4) 119.4(2) C(4)-C(5)-H(5) 119.6 C(24)-Sn(1)-C(23) 109.9(3) C(6)-C(5)-H(5) 119.6 C(4)-Sn(1)-C(23) 111.5(2) C(21)-C(16)-C(17) 116.0(5) C(24)-Sn(1)-C(1) 119.8(2) C(21)-C(16)-C(1) 119.2(5) C(4)-Sn(1)-C(1) 84.0(2) C(17)-C(16)-C(1) 124.6(5) C(23)-Sn(1)-C(1) 110.0(2) C(2)-C(1)-C(16) 127.1(5) C(1)-C(2)-C(9) 124.6(5) C(2)-C(1)-Sn(1) 109.6(4) C(1)-C(2)-C(3) 119.0(5) C(16)-C(1)-Sn(1) 123.1(4) C(9)-C(2)-C(3) 116.4(5) C(13)-C(12)-C(11) 118.2(6) Sn(1)-C(24)-H(24A) 109.5 C(13)-C(12)-C(15) 121.3(6) Sn(1)-C(24)-H(24B) 109.5 C(11)-C(12)-C(15) 120.5(6) H(24A)-C(24)-H(24B) 109.5 C(20)-C(21)-C(16) 121.9(5) Sn(1)-C(24)-H(24C) 109.5 C(20)-C(21)-H(21) 119.0 H(24A)-C(24)-H(24C) 109.5 C(16)-C(21)-H(21) 119.0 H(24B)-C(24)-H(24C) 109.5 C(8)-C(3)-C(4) 119.3(5) C(9)-C(10)-C(11) 120.0(5) C(8)-C(3)-C(2) 121.2(5) C(9)-C(10)-H(10) 120.0 C(4)-C(3)-C(2) 119.5(5) C(11)-C(10)-H(10) 120.0 C(7)-C(8)-C(3) 119.6(5) C(4)-C(5)-C(6) 120.8(6) C(7)-C(8)-H(8) 120.2

175 C(3)-C(8)-H(8) 120.2 C(17)-C(18)-H(18) 119.6 C(6)-C(7)-C(8) 121.2(6) C(19)-C(18)-H(18) 119.6 C(6)-C(7)-H(7) 119.4 C(5)-C(4)-C(3) 119.6(5) C(8)-C(7)-H(7) 119.4 C(5)-C(4)-Sn(1) 132.7(5) C(7)-C(6)-C(5) 119.5(6) C(3)-C(4)-Sn(1) 107.5(4) C(7)-C(6)-H(6) 120.2 C(19)-C(20)-C(21) 121.1(6) C(5)-C(6)-H(6) 120.2 C(19)-C(20)-H(20) 119.4 C(9)-C(14)-C(13) 120.6(6) C(21)-C(20)-H(20) 119.4 C(9)-C(14)-H(14) 119.7 C(20)-C(19)-C(18) 118.0(6) C(13)-C(14)-H(14) 119.7 C(20)-C(19)-C(22) 121.0(6) C(10)-C(9)-C(14) 118.7(5) C(18)-C(19)-C(22) 121.0(6) C(10)-C(9)-C(2) 120.7(5) Sn(1)-C(23)-H(23A) 109.5 C(14)-C(9)-C(2) 120.6(5) Sn(1)-C(23)-H(23B) 109.5 C(12)-C(13)-C(14) 121.1(7) H(23A)-C(23)-H(23B) 109.5 C(12)-C(13)-H(13) 119.4 Sn(1)-C(23)-H(23C) 109.5 C(14)-C(13)-H(13) 119.4 H(23A)-C(23)-H(23C) 109.5 C(18)-C(17)-C(16) 122.1(5) H(23B)-C(23)-H(23C) 109.5 C(18)-C(17)-H(17) 118.9 C(12)-C(11)-C(10) 121.3(5) C(16)-C(17)-H(17) 118.9 C(12)-C(11)-H(11) 119.4 C(12)-C(15)-H(15A) 109.5 C(10)-C(11)-H(11) 119.4 C(12)-C(15)-H(15B) 109.5 C(19)-C(22)-H(22A) 109.5 H(15A)-C(15)-H(15B) 109.5 C(19)-C(22)-H(22B) 109.5 C(12)-C(15)-H(15C) 109.5 H(22A)-C(22)-H(22B) 109.5 H(15A)-C(15)-H(15C) 109.5 C(19)-C(22)-H(22C) 109.5 H(15B)-C(15)-H(15C) 109.5 H(22A)-C(22)-H(22C) 109.5 C(17)-C(18)-C(19) 120.7(6) H(22B)-C(22)-H(22C) 109.5 ______Symmetry transformations used to generate equivalent atoms:

Table A13. Crystal data and structure refinement for 2-7CF3.

Crystallographer Adrian Houghton Empirical formula C24 H18 F6 Sn Formula weight 539.07 Temperature 173(2) K Wavelength 0.71073 Å Crystal system Orthorhombic Space group P n m a Unit cell dimensions a = 17.6821(3) Å a= 90°. b = 9.4841(3) Å b= 90°. c = 13.6061(6) Å g = 90°. Volume 2281.73(13) Å3 Z 4 Density (calculated) 1.569 Mg/m3 Absorption coefficient 1.176 mm-1 F(000) 1064 Crystal size 0.06 x 0.04 x 0.04 mm3 Theta range for data collection 2.62 to 27.49°. Index ranges -22<=h<=22, -12<=k<=12, -17<=l<=17 Reflections collected 17415 Independent reflections 2767 [R(int) = 0.0732] Completeness to theta = 27.49° 99.7 % Absorption correction Semi-empirical from equivalents

176 Max. and min. transmission 0.9545 and 0.9328 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 2767 / 0 / 172 Goodness-of-fit on F2 1.126 Final R indices [I>2sigma(I)] R1 = 0.0573, wR2 = 0.1290 R indices (all data) R1 = 0.0810, wR2 = 0.1423 Largest diff. peak and hole 0.971 and -0.958 e.Å-3

Table A14. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 2- ij 7CF3. U(eq) is defined as one third of the trace of the orthogonalized U tensor. ______x y z U(eq) ______Sn(1) -1654(1) 2500 6253(1) 46(1) F(1) 3422(3) 1685(10) 4759(7) 165(5) F(2) 3504(3) 1617(10) 5954(8) 154(4) F(3) 718(6) 1585(10) 10889(5) 144(3) F(4) 1544(6) 1564(9) 10358(6) 147(4) C(1) -2209(4) 4350(8) 6769(5) 83(2) C(2) -1308(4) 2500 4742(5) 40(2) C(3) -1716(4) 2500 3869(6) 48(2) C(4) -1345(5) 2500 2964(6) 53(2) C(5) -566(5) 2500 2939(6) 51(2) C(6) -150(4) 2500 3797(5) 44(2) C(7) -512(4) 2500 4714(5) 37(2) C(8) -83(4) 2500 5646(5) 38(1) C(9) -453(4) 2500 6512(5) 43(2) C(10) 764(4) 2500 5608(5) 40(2) C(11) 1164(3) 1242(5) 5589(4) 50(1) C(12) 1944(3) 1249(5) 5539(4) 50(1) C(13) 2335(4) 2500 5497(5) 40(2) C(14) 3180(4) 2500 5415(6) 48(2) C(15) -68(4) 2500 7471(5) 43(2) C(16) 107(4) 1256(6) 7937(4) 61(2) C(17) 456(4) 1249(7) 8847(5) 68(2) C(18) 625(4) 2500 9302(6) 53(2) C(19) 997(5) 2500 10281(7) 76(3)

Table A15. Bond lengths [Å] and angles [°] for 2-7CF3. ______Sn(1)-C(1) 2.129(6) F(4)-F(4)#1 1.775(18) Sn(1)-C(1)#1 2.129(6) C(1)-H(1A) 0.9600 Sn(1)-C(2) 2.145(7) C(1)-H(1B) 0.9600 Sn(1)-C(9) 2.152(7) C(1)-H(1C) 0.9600 F(1)-C(14) 1.256(9) C(2)-C(3) 1.391(10) F(1)-F(1)#1 1.55(2) C(2)-C(7) 1.408(10) F(1)-F(2) 1.632(12) C(3)-C(4) 1.395(11) F(2)-C(14) 1.251(8) C(3)-H(3) 0.9599 F(2)-F(2)#1 1.675(19) C(4)-C(5) 1.378(12) F(3)-C(19) 1.296(10) C(4)-H(4) 0.9600 F(3)-F(4) 1.628(12) C(5)-C(6) 1.380(11) F(3)-F(3)#1 1.736(19) C(5)-H(5) 0.9601 F(4)-C(19) 1.316(10) C(6)-C(7) 1.402(9)

177 C(6)-H(6) 0.9600 C(14)-F(2)#1 1.251(8) C(7)-C(8) 1.478(10) C(14)-F(1)#1 1.256(9) C(8)-C(9) 1.347(10) C(15)-C(16)#1 1.375(7) C(8)-C(10) 1.499(9) C(15)-C(16) 1.375(7) C(9)-C(15) 1.471(10) C(16)-C(17) 1.384(8) C(10)-C(11)#1 1.387(6) C(16)-H(16) 0.9601 C(10)-C(11) 1.387(6) C(17)-C(18) 1.371(8) C(11)-C(12) 1.381(7) C(17)-H(17) 0.9600 C(11)-H(11) 0.9600 C(18)-C(17)#1 1.371(8) C(12)-C(13) 1.374(6) C(18)-C(19) 1.486(12) C(12)-H(12) 0.9600 C(19)-F(3)#1 1.296(10) C(13)-C(12)#1 1.374(6) C(19)-F(4)#1 1.316(10) C(13)-C(14) 1.498(10)

C(1)-Sn(1)-C(1)#1 110.9(4) C(9)-C(8)-C(7) 120.1(6) C(1)-Sn(1)-C(2) 116.6(2) C(9)-C(8)-C(10) 121.0(6) C(1)#1-Sn(1)-C(2) 116.6(2) C(7)-C(8)-C(10) 118.9(6) C(1)-Sn(1)-C(9) 113.6(2) C(8)-C(9)-C(15) 123.5(6) C(1)#1-Sn(1)-C(9) 113.6(2) C(8)-C(9)-Sn(1) 109.6(5) C(2)-Sn(1)-C(9) 82.9(3) C(15)-C(9)-Sn(1) 126.9(5) C(14)-F(1)-F(1)#1 52.0(6) C(11)#1-C(10)-C(11) 118.7(6) C(14)-F(1)-F(2) 49.2(5) C(11)#1-C(10)-C(8) 120.7(3) F(1)#1-F(1)-F(2) 92.3(5) C(11)-C(10)-C(8) 120.7(3) C(14)-F(2)-F(1) 49.5(5) C(12)-C(11)-C(10) 120.4(5) C(14)-F(2)-F(2)#1 48.0(6) C(12)-C(11)-H(11) 119.8 F(1)-F(2)-F(2)#1 87.7(5) C(10)-C(11)-H(11) 119.8 C(19)-F(3)-F(4) 52.0(5) C(13)-C(12)-C(11) 120.6(5) C(19)-F(3)-F(3)#1 48.0(5) C(13)-C(12)-H(12) 120.0 F(4)-F(3)-F(3)#1 90.7(5) C(11)-C(12)-H(12) 119.4 C(19)-F(4)-F(3) 50.9(5) C(12)-C(13)-C(12)#1 119.4(7) C(19)-F(4)-F(4)#1 47.6(5) C(12)-C(13)-C(14) 120.3(3) F(3)-F(4)-F(4)#1 89.3(5) C(12)#1-C(13)-C(14) 120.3(3) Sn(1)-C(1)-H(1A) 109.9 F(2)#1-C(14)-F(2) 84.0(11) Sn(1)-C(1)-H(1B) 109.0 F(2)#1-C(14)-F(1)#1 81.3(7) H(1A)-C(1)-H(1B) 109.5 F(2)-C(14)-F(1)#1 132.2(7) Sn(1)-C(1)-H(1C) 109.6 F(2)#1-C(14)-F(1) 132.2(7) H(1A)-C(1)-H(1C) 109.5 F(2)-C(14)-F(1) 81.3(7) H(1B)-C(1)-H(1C) 109.5 F(1)#1-C(14)-F(1) 76.0(11) C(3)-C(2)-C(7) 119.7(7) F(2)#1-C(14)-C(13) 114.4(6) C(3)-C(2)-Sn(1) 132.2(6) F(2)-C(14)-C(13) 114.4(6) C(7)-C(2)-Sn(1) 108.1(5) F(1)#1-C(14)-C(13) 113.1(6) C(2)-C(3)-C(4) 120.6(7) F(1)-C(14)-C(13) 113.1(6) C(2)-C(3)-H(3) 118.6 C(16)#1-C(15)-C(16) 118.3(7) C(4)-C(3)-H(3) 120.8 C(16)#1-C(15)-C(9) 120.9(3) C(5)-C(4)-C(3) 119.6(8) C(16)-C(15)-C(9) 120.9(3) C(5)-C(4)-H(4) 120.9 C(15)-C(16)-C(17) 121.1(6) C(3)-C(4)-H(4) 119.6 C(15)-C(16)-H(16) 118.8 C(4)-C(5)-C(6) 120.8(7) C(17)-C(16)-H(16) 120.1 C(4)-C(5)-H(5) 119.7 C(18)-C(17)-C(16) 119.8(6) C(6)-C(5)-H(5) 119.5 C(18)-C(17)-H(17) 120.3 C(5)-C(6)-C(7) 120.6(7) C(16)-C(17)-H(17) 119.9 C(5)-C(6)-H(6) 119.9 C(17)-C(18)-C(17)#1 119.8(7) C(7)-C(6)-H(6) 119.5 C(17)-C(18)-C(19) 120.1(4) C(6)-C(7)-C(2) 118.8(7) C(17)#1-C(18)-C(19) 120.1(4) C(6)-C(7)-C(8) 121.9(6) F(3)-C(19)-F(3)#1 84.1(11) C(2)-C(7)-C(8) 119.3(6) F(3)-C(19)-F(4)#1 132.9(9) 178 F(3)#1-C(19)-F(4)#1 77.1(7) F(3)-C(19)-C(18) 113.8(7) F(3)-C(19)-F(4) 77.1(7) F(3)#1-C(19)-C(18) 113.8(7) F(3)#1-C(19)-F(4) 132.9(9) F(4)#1-C(19)-C(18) 113.3(7) F(4)#1-C(19)-F(4) 84.8(11) F(4)-C(19)-C(18) 113.3(7) ______Symmetry transformations used to generate equivalent atoms: #1 x,-y+1/2,z

Table A16. Crystal data and structure refinement for 2-7F.

Crystallographer Adrian Houghton Empirical formula C22 H18 F2 Sn Formula weight 439.05 Temperature 173(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group C 2/c Unit cell dimensions a = 22.0110(6) Å a= 90°. b = 7.0410(2) Å b= 94.2060(10)°. c = 24.7450(7) Å g = 90°. Volume 3824.64(19) Å3 Z 8 Density (calculated) 1.525 Mg/m3 Absorption coefficient 1.355 mm-1 F(000) 1744 Crystal size 0.06 x 0.06 x 0.04 mm3 Theta range for data collection 2.39 to 27.48°. Index ranges -27<=h<=28, -9<=k<=9, -32<=l<=32 Reflections collected 8151 Independent reflections 4355 [R(int) = 0.0355] Completeness to theta = 27.48° 99.5 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9478 and 0.9231 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 4355 / 0 / 228 Goodness-of-fit on F2 1.291 Final R indices [I>2sigma(I)] R1 = 0.0484, wR2 = 0.1372 R indices (all data) R1 = 0.0652, wR2 = 0.1678 Largest diff. peak and hole 1.248 and -1.013 e.Å-3

Table A17. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 2-7F. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ______x y z U(eq) ______Sn(1) 7202(1) 2228(1) 1445(1) 28(1) F(1) 3460(2) -197(6) 934(2) 54(1) C(15) 6120(2) -458(8) 1839(2) 25(1) F(2) 5661(2) -4806(6) 2842(2) 51(1) C(2) 5917(2) 1953(7) 1114(2) 22(1) C(4) 6767(2) 3961(8) 823(2) 28(1)

179 C(3) 6148(2) 3505(8) 765(2) 23(1) C(18) 5809(3) -3384(9) 2515(2) 34(1) C(14) 4826(3) 2484(8) 1291(3) 30(1) C(5) 6984(3) 5433(9) 512(3) 34(1) C(9) 5259(2) 1425(8) 1047(2) 23(1) C(1) 6298(2) 1087(7) 1476(2) 23(1) C(8) 5763(2) 4525(8) 407(2) 28(1) C(7) 5992(3) 5991(9) 99(2) 33(1) C(12) 4058(2) 342(9) 968(2) 34(1) C(16) 5887(3) -79(9) 2331(2) 33(1) C(6) 6601(3) 6429(9) 154(2) 37(1) C(10) 5072(3) -194(9) 757(2) 34(1) C(17) 5729(3) -1558(10) 2674(2) 39(1) C(13) 4216(3) 1956(9) 1254(2) 33(1) C(21) 7515(3) 3805(11) 2156(3) 50(2) C(22) 7852(3) 168(10) 1228(3) 53(2) C(11) 4464(3) -749(10) 711(3) 39(1) C(19) 6024(3) -3824(9) 2029(3) 35(1) C(20) 6183(3) -2351(8) 1688(3) 32(1)

Table A18. Bond lengths [Å] and angles [°] for 2-7F. ______Sn(1)-C(22) 2.134(6) C(8)-C(7) 1.398(8) Sn(1)-C(4) 2.135(6) C(8)-H(8) 0.9500 Sn(1)-C(21) 2.150(7) C(7)-C(6) 1.374(8) Sn(1)-C(1) 2.153(5) C(7)-H(7) 0.9500 F(1)-C(12) 1.365(6) C(12)-C(13) 1.370(9) C(15)-C(16) 1.382(8) C(12)-C(11) 1.371(9) C(15)-C(20) 1.394(7) C(16)-C(17) 1.403(8) C(15)-C(1) 1.481(7) C(16)-H(16) 0.9500 F(2)-C(18) 1.343(7) C(6)-H(6) 0.9500 C(2)-C(1) 1.330(7) C(10)-C(11) 1.390(8) C(2)-C(9) 1.491(7) C(10)-H(10) 0.9500 C(2)-C(3) 1.503(7) C(17)-H(17) 0.9500 C(4)-C(5) 1.396(8) C(13)-H(13) 0.9500 C(4)-C(3) 1.398(7) C(21)-H(21A) 0.9800 C(3)-C(8) 1.382(7) C(21)-H(21B) 0.9800 C(18)-C(19) 1.360(8) C(21)-H(21C) 0.9800 C(18)-C(17) 1.360(9) C(22)-H(22A) 0.9800 C(14)-C(9) 1.384(7) C(22)-H(22B) 0.9800 C(14)-C(13) 1.389(8) C(22)-H(22C) 0.9800 C(14)-H(14) 0.9500 C(11)-H(11) 0.9500 C(5)-C(6) 1.371(9) C(19)-C(20) 1.398(8) C(5)-H(5) 0.9500 C(19)-H(19) 0.9500 C(9)-C(10) 1.393(8) C(20)-H(20) 0.9500

C(22)-Sn(1)-C(4) 118.7(3) C(1)-C(2)-C(9) 121.2(5) C(22)-Sn(1)-C(21) 112.1(3) C(1)-C(2)-C(3) 119.8(5) C(4)-Sn(1)-C(21) 113.3(3) C(9)-C(2)-C(3) 119.0(4) C(22)-Sn(1)-C(1) 113.2(2) C(5)-C(4)-C(3) 119.1(5) C(4)-Sn(1)-C(1) 82.7(2) C(5)-C(4)-Sn(1) 131.9(4) C(21)-Sn(1)-C(1) 113.9(3) C(3)-C(4)-Sn(1) 108.9(4) C(16)-C(15)-C(20) 118.2(5) C(8)-C(3)-C(4) 119.5(5) C(16)-C(15)-C(1) 121.6(5) C(8)-C(3)-C(2) 122.0(5) C(20)-C(15)-C(1) 120.2(5) C(4)-C(3)-C(2) 118.5(5)

180 F(2)-C(18)-C(19) 118.6(6) C(11)-C(10)-C(9) 121.3(5) F(2)-C(18)-C(17) 119.2(5) C(11)-C(10)-H(10) 119.4 C(19)-C(18)-C(17) 122.2(5) C(9)-C(10)-H(10) 119.4 C(9)-C(14)-C(13) 121.4(5) C(18)-C(17)-C(16) 118.9(5) C(9)-C(14)-H(14) 119.3 C(18)-C(17)-H(17) 120.6 C(13)-C(14)-H(14) 119.3 C(16)-C(17)-H(17) 120.6 C(6)-C(5)-C(4) 121.1(5) C(12)-C(13)-C(14) 117.7(5) C(6)-C(5)-H(5) 119.4 C(12)-C(13)-H(13) 121.2 C(4)-C(5)-H(5) 119.4 C(14)-C(13)-H(13) 121.2 C(14)-C(9)-C(10) 118.5(5) Sn(1)-C(21)-H(21A) 109.5 C(14)-C(9)-C(2) 120.8(5) Sn(1)-C(21)-H(21B) 109.5 C(10)-C(9)-C(2) 120.6(5) H(21A)-C(21)-H(21B) 109.5 C(2)-C(1)-C(15) 124.3(5) Sn(1)-C(21)-H(21C) 109.5 C(2)-C(1)-Sn(1) 110.1(4) H(21A)-C(21)-H(21C) 109.5 C(15)-C(1)-Sn(1) 125.6(4) H(21B)-C(21)-H(21C) 109.5 C(3)-C(8)-C(7) 120.4(5) Sn(1)-C(22)-H(22A) 109.5 C(3)-C(8)-H(8) 119.8 Sn(1)-C(22)-H(22B) 109.5 C(7)-C(8)-H(8) 119.8 H(22A)-C(22)-H(22B) 109.5 C(6)-C(7)-C(8) 120.0(5) Sn(1)-C(22)-H(22C) 109.5 C(6)-C(7)-H(7) 120.0 H(22A)-C(22)-H(22C) 109.5 C(8)-C(7)-H(7) 120.0 H(22B)-C(22)-H(22C) 109.5 F(1)-C(12)-C(13) 118.1(6) C(12)-C(11)-C(10) 117.5(6) F(1)-C(12)-C(11) 118.3(6) C(12)-C(11)-H(11) 121.3 C(13)-C(12)-C(11) 123.6(5) C(10)-C(11)-H(11) 121.3 C(15)-C(16)-C(17) 120.9(6) C(18)-C(19)-C(20) 118.9(6) C(15)-C(16)-H(16) 119.5 C(18)-C(19)-H(19) 120.5 C(17)-C(16)-H(16) 119.5 C(20)-C(19)-H(19) 120.5 C(5)-C(6)-C(7) 120.0(5) C(15)-C(20)-C(19) 120.9(5) C(5)-C(6)-H(6) 120.0 C(15)-C(20)-H(20) 119.6 C(7)-C(6)-H(6) 120.0 C(19)-C(20)-H(20) 119.6 ______Symmetry transformations used to generate equivalent atoms:

Table A19. Crystal data and structure refinement for 2-7C6F5.

Crystallographer Adrian Houghton Empirical formula C22 H10 F10 Sn Formula weight 582.99 Temperature 173(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group P 21/c Unit cell dimensions a = 8.8320(3) Å a= 90.0000(10)°. b = 17.0510(5) Å b= 100.5590(10)°. c = 28.7090(9) Å g = 90.0000(10)°. Volume 4250.2(2) Å3 Z 8 Density (calculated) 1.822 Mg/m3 Absorption coefficient 1.296 mm-1 F(000) 2256 Crystal size 0.20 x 0.16 x 0.12 mm3 Theta range for data collection 1.40 to 27.62°. Index ranges -11<=h<=11, -22<=k<=22, -37<=l<=37

181 Reflections collected 30330 Independent reflections 9595 [R(int) = 0.0556] Completeness to theta = 25.00° 97.6 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.8600 and 0.7816 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 9595 / 0 / 595 Goodness-of-fit on F2 1.258 Final R indices [I>2sigma(I)] R1 = 0.0621, wR2 = 0.0949 R indices (all data) R1 = 0.0839, wR2 = 0.1014 Largest diff. peak and hole 0.549 and -0.466 e.Å-3

Table A20. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 2- ij 7C6F5. U(eq) is defined as one third of the trace of the orthogonalized U tensor. ______x y z U(eq) ______Sn(1) 4481(1) 5143(1) 1595(1) 40(1) C(5) 1917(5) 4370(3) 1918(2) 32(1) C(11) 669(5) 3495(3) 1233(2) 33(1) C(10) 778(6) 4185(3) 2179(2) 39(1) C(12) 523(6) 2747(3) 1403(2) 37(1) C(19) 3673(6) 2834(3) 241(2) 45(1) C(6) 3078(6) 4906(3) 2108(2) 36(1) C(13) -670(6) 2260(3) 1213(2) 41(1) C(3) 3024(5) 4267(3) 1192(2) 34(1) C(17) 3191(5) 3935(3) 733(2) 34(1) C(9) 791(6) 4521(3) 2616(2) 46(1) C(22) 3192(6) 4401(3) 337(2) 45(1) C(14) -1769(6) 2523(3) 846(2) 51(2) C(4) 1947(5) 4045(3) 1443(2) 31(1) C(15) -1668(6) 3265(3) 668(2) 52(2) C(8) 1920(7) 5050(3) 2801(2) 47(1) C(21) 3386(7) 4103(4) -92(2) 50(2) C(7) 3062(6) 5246(3) 2544(2) 46(1) C(18) 3464(6) 3141(3) 669(2) 38(1) C(16) -447(6) 3738(3) 862(2) 43(1) C(20) 3603(6) 3315(4) -140(2) 51(2) Sn(2) 347(1) 2355(1) 3274(1) 40(1) C(42) 1274(6) 4207(4) 4995(2) 50(2) C(26) -2038(5) 3458(3) 3390(2) 33(1) C(33) -3043(5) 4053(3) 3570(2) 35(1) C(39) -57(5) 3576(3) 4122(2) 33(1) C(27) -2587(5) 3115(3) 2914(2) 33(1) C(34) -3169(6) 4815(3) 3397(2) 42(1) C(29) -2091(6) 2249(3) 2295(2) 44(1) C(28) -1618(6) 2573(3) 2741(2) 38(1) C(41) 1184(6) 4648(3) 4594(2) 46(1) C(43) 691(6) 3458(4) 4968(2) 49(2) C(25) -698(5) 3233(3) 3651(2) 35(1) C(38) -3859(6) 3877(3) 3920(2) 48(1) C(40) 523(6) 4330(3) 4167(2) 38(1) C(30) -3496(6) 2445(3) 2025(2) 45(1) C(32) -4009(6) 3301(3) 2638(2) 39(1)

182 C(36) -4862(7) 5165(4) 3913(3) 63(2) C(44) 56(6) 3148(3) 4536(2) 44(1) C(31) -4462(6) 2956(3) 2196(2) 44(1) C(35) -4049(7) 5374(3) 3570(3) 56(2) C(37) -4773(7) 4419(4) 4090(3) 62(2) F(6) 3548(3) 2647(2) 1037(1) 46(1) F(16) 455(4) 4783(2) 3779(1) 53(1) F(1) 1569(4) 2486(2) 1766(1) 47(1) F(11) -2421(4) 5023(2) 3052(1) 61(1) F(2) -752(4) 1530(2) 1377(1) 56(1) F(10) 2981(4) 5183(2) 375(1) 57(1) F(20) -472(4) 2408(2) 4515(1) 63(1) F(5) -385(4) 4458(2) 675(1) 60(1) F(7) 3921(4) 2065(2) 200(1) 56(1) F(9) 3370(4) 4587(2) -466(1) 71(1) F(15) -3784(4) 3153(2) 4106(1) 66(1) F(17) 1730(4) 5380(2) 4623(1) 64(1) F(12) -4112(5) 6104(2) 3401(2) 79(1) F(8) 3768(4) 3019(2) -560(1) 71(1) F(3) -2930(4) 2055(2) 654(2) 76(1) F(19) 762(5) 3028(2) 5361(1) 76(1) F(18) 1903(4) 4501(3) 5419(1) 76(1) F(4) -2742(4) 3514(2) 307(2) 88(2) C(1) 6838(6) 4795(4) 1740(2) 68(2) F(13) -5727(5) 5709(3) 4078(2) 102(2) F(14) -5548(5) 4225(3) 4431(2) 104(2) C(23) 325(8) 1226(3) 3586(3) 65(2) C(24) 2536(7) 2699(4) 3138(3) 70(2) C(2) 4106(8) 6307(3) 1334(2) 64(2)

Table A21. Bond lengths [Å] and angles [°] for 2-7C6F5. ______Sn(1)-C(2) 2.125(6) C(17)-C(18) 1.392(7) Sn(1)-C(6) 2.130(5) C(9)-C(8) 1.377(8) Sn(1)-C(1) 2.131(6) C(9)-H(9) 0.9500 Sn(1)-C(3) 2.162(5) C(22)-F(10) 1.352(6) C(5)-C(10) 1.397(7) C(22)-C(21) 1.371(8) C(5)-C(6) 1.407(7) C(14)-F(3) 1.336(6) C(5)-C(4) 1.476(7) C(14)-C(15) 1.374(8) C(11)-C(16) 1.376(7) C(15)-F(4) 1.340(6) C(11)-C(12) 1.380(7) C(15)-C(16) 1.379(7) C(11)-C(4) 1.506(6) C(8)-C(7) 1.395(8) C(10)-C(9) 1.378(7) C(8)-H(8) 0.9500 C(10)-H(10) 0.9500 C(21)-F(9) 1.352(6) C(12)-F(1) 1.337(6) C(21)-C(20) 1.368(8) C(12)-C(13) 1.373(7) C(7)-H(7) 0.9500 C(19)-F(7) 1.338(6) C(18)-F(6) 1.343(6) C(19)-C(20) 1.360(8) C(16)-F(5) 1.345(6) C(19)-C(18) 1.379(7) C(20)-F(8) 1.339(6) C(6)-C(7) 1.383(7) Sn(2)-C(24) 2.123(6) C(13)-F(2) 1.336(6) Sn(2)-C(23) 2.125(6) C(13)-C(14) 1.369(8) Sn(2)-C(28) 2.126(5) C(3)-C(4) 1.349(6) Sn(2)-C(25) 2.152(5) C(3)-C(17) 1.467(7) C(42)-F(18) 1.339(6) C(17)-C(22) 1.388(7) C(42)-C(41) 1.364(8)

183 C(42)-C(43) 1.375(9) C(30)-C(31) 1.371(7) C(26)-C(25) 1.336(7) C(30)-H(30) 0.9500 C(26)-C(27) 1.484(7) C(32)-C(31) 1.388(7) C(26)-C(33) 1.501(6) C(32)-H(32) 0.9500 C(33)-C(38) 1.373(7) C(36)-F(13) 1.342(6) C(33)-C(34) 1.387(7) C(36)-C(37) 1.367(10) C(39)-C(40) 1.380(7) C(36)-C(35) 1.368(10) C(39)-C(44) 1.384(7) C(44)-F(20) 1.343(6) C(39)-C(25) 1.486(7) C(31)-H(31) 0.9500 C(27)-C(32) 1.393(7) C(35)-F(12) 1.334(7) C(27)-C(28) 1.410(7) C(37)-F(14) 1.335(7) C(34)-F(11) 1.334(6) C(1)-H(1A) 0.9800 C(34)-C(35) 1.378(7) C(1)-H(1B) 0.9800 C(29)-C(30) 1.379(7) C(1)-H(1C) 0.9800 C(29)-C(28) 1.386(7) C(23)-H(23A) 0.9800 C(29)-H(29) 0.9500 C(23)-H(23B) 0.9800 C(41)-F(17) 1.335(6) C(23)-H(23C) 0.9800 C(41)-C(40) 1.371(7) C(24)-H(24A) 0.9800 C(43)-F(19) 1.337(6) C(24)-H(24B) 0.9800 C(43)-C(44) 1.370(8) C(24)-H(24C) 0.9800 C(38)-F(15) 1.342(7) C(2)-H(2A) 0.9800 C(38)-C(37) 1.374(8) C(2)-H(2B) 0.9800 C(40)-F(16) 1.348(6) C(2)-H(2C) 0.9800

C(2)-Sn(1)-C(6) 110.3(2) C(18)-C(17)-C(3) 122.8(5) C(2)-Sn(1)-C(1) 114.4(3) C(8)-C(9)-C(10) 120.5(5) C(6)-Sn(1)-C(1) 118.9(2) C(8)-C(9)-H(9) 119.7 C(2)-Sn(1)-C(3) 114.7(2) C(10)-C(9)-H(9) 119.7 C(6)-Sn(1)-C(3) 82.75(19) F(10)-C(22)-C(21) 118.7(5) C(1)-Sn(1)-C(3) 112.2(2) F(10)-C(22)-C(17) 118.5(5) C(10)-C(5)-C(6) 119.0(5) C(21)-C(22)-C(17) 122.8(5) C(10)-C(5)-C(4) 123.1(4) F(3)-C(14)-C(13) 120.3(5) C(6)-C(5)-C(4) 117.8(4) F(3)-C(14)-C(15) 119.6(5) C(16)-C(11)-C(12) 116.9(4) C(13)-C(14)-C(15) 120.1(5) C(16)-C(11)-C(4) 120.1(4) C(3)-C(4)-C(5) 121.4(4) C(12)-C(11)-C(4) 123.0(5) C(3)-C(4)-C(11) 120.7(5) C(9)-C(10)-C(5) 120.6(5) C(5)-C(4)-C(11) 117.8(4) C(9)-C(10)-H(10) 119.7 F(4)-C(15)-C(14) 119.7(5) C(5)-C(10)-H(10) 119.7 F(4)-C(15)-C(16) 121.1(5) F(1)-C(12)-C(13) 118.7(5) C(14)-C(15)-C(16) 119.2(5) F(1)-C(12)-C(11) 119.2(4) C(9)-C(8)-C(7) 119.7(5) C(13)-C(12)-C(11) 122.2(5) C(9)-C(8)-H(8) 120.1 F(7)-C(19)-C(20) 120.2(5) C(7)-C(8)-H(8) 120.1 F(7)-C(19)-C(18) 120.2(5) F(9)-C(21)-C(20) 120.1(5) C(20)-C(19)-C(18) 119.6(5) F(9)-C(21)-C(22) 120.0(6) C(7)-C(6)-C(5) 119.7(5) C(20)-C(21)-C(22) 119.9(5) C(7)-C(6)-Sn(1) 130.6(4) C(6)-C(7)-C(8) 120.5(5) C(5)-C(6)-Sn(1) 109.3(4) C(6)-C(7)-H(7) 119.8 F(2)-C(13)-C(14) 119.9(5) C(8)-C(7)-H(7) 119.8 F(2)-C(13)-C(12) 120.6(5) F(6)-C(18)-C(19) 117.7(5) C(14)-C(13)-C(12) 119.4(5) F(6)-C(18)-C(17) 119.5(5) C(4)-C(3)-C(17) 124.7(4) C(19)-C(18)-C(17) 122.8(5) C(4)-C(3)-Sn(1) 108.5(4) F(5)-C(16)-C(11) 120.5(4) C(17)-C(3)-Sn(1) 126.8(3) F(5)-C(16)-C(15) 117.4(5) C(22)-C(17)-C(18) 115.0(5) C(11)-C(16)-C(15) 122.1(5) C(22)-C(17)-C(3) 122.0(5) F(8)-C(20)-C(19) 120.0(6) 184 F(8)-C(20)-C(21) 120.1(6) C(41)-C(40)-C(39) 122.9(5) C(19)-C(20)-C(21) 119.9(6) C(31)-C(30)-C(29) 120.4(5) C(24)-Sn(2)-C(23) 114.0(3) C(31)-C(30)-H(30) 119.8 C(24)-Sn(2)-C(28) 118.0(2) C(29)-C(30)-H(30) 119.8 C(23)-Sn(2)-C(28) 113.1(2) C(31)-C(32)-C(27) 120.1(5) C(24)-Sn(2)-C(25) 112.9(2) C(31)-C(32)-H(32) 119.9 C(23)-Sn(2)-C(25) 112.4(2) C(27)-C(32)-H(32) 119.9 C(28)-Sn(2)-C(25) 82.60(19) F(13)-C(36)-C(37) 120.7(7) F(18)-C(42)-C(41) 120.8(6) F(13)-C(36)-C(35) 118.9(7) F(18)-C(42)-C(43) 119.2(6) C(37)-C(36)-C(35) 120.4(5) C(41)-C(42)-C(43) 120.0(5) F(20)-C(44)-C(43) 119.0(5) C(25)-C(26)-C(27) 120.7(4) F(20)-C(44)-C(39) 119.2(5) C(25)-C(26)-C(33) 121.3(5) C(43)-C(44)-C(39) 121.8(6) C(27)-C(26)-C(33) 118.0(4) C(30)-C(31)-C(32) 120.2(5) C(38)-C(33)-C(34) 116.6(5) C(30)-C(31)-H(31) 119.9 C(38)-C(33)-C(26) 121.7(5) C(32)-C(31)-H(31) 119.9 C(34)-C(33)-C(26) 121.6(5) F(12)-C(35)-C(36) 120.8(6) C(40)-C(39)-C(44) 116.3(5) F(12)-C(35)-C(34) 120.3(7) C(40)-C(39)-C(25) 121.7(5) C(36)-C(35)-C(34) 119.0(6) C(44)-C(39)-C(25) 121.9(5) F(14)-C(37)-C(36) 120.0(6) C(32)-C(27)-C(28) 119.4(5) F(14)-C(37)-C(38) 120.5(7) C(32)-C(27)-C(26) 122.9(5) C(36)-C(37)-C(38) 119.5(6) C(28)-C(27)-C(26) 117.7(4) Sn(1)-C(1)-H(1A) 109.5 F(11)-C(34)-C(35) 118.1(5) Sn(1)-C(1)-H(1B) 109.5 F(11)-C(34)-C(33) 119.7(5) H(1A)-C(1)-H(1B) 109.5 C(35)-C(34)-C(33) 122.2(6) Sn(1)-C(1)-H(1C) 109.5 C(30)-C(29)-C(28) 120.7(5) H(1A)-C(1)-H(1C) 109.5 C(30)-C(29)-H(29) 119.6 H(1B)-C(1)-H(1C) 109.5 C(28)-C(29)-H(29) 119.6 Sn(2)-C(23)-H(23A) 109.5 C(29)-C(28)-C(27) 119.1(5) Sn(2)-C(23)-H(23B) 109.5 C(29)-C(28)-Sn(2) 131.5(4) H(23A)-C(23)-H(23B) 109.5 C(27)-C(28)-Sn(2) 109.3(4) Sn(2)-C(23)-H(23C) 109.5 F(17)-C(41)-C(42) 119.9(5) H(23A)-C(23)-H(23C) 109.5 F(17)-C(41)-C(40) 121.0(5) H(23B)-C(23)-H(23C) 109.5 C(42)-C(41)-C(40) 119.1(6) Sn(2)-C(24)-H(24A) 109.5 F(19)-C(43)-C(44) 120.1(6) Sn(2)-C(24)-H(24B) 109.5 F(19)-C(43)-C(42) 120.1(6) H(24A)-C(24)-H(24B) 109.5 C(44)-C(43)-C(42) 119.8(5) Sn(2)-C(24)-H(24C) 109.5 C(26)-C(25)-C(39) 123.2(4) H(24A)-C(24)-H(24C) 109.5 C(26)-C(25)-Sn(2) 109.6(4) H(24B)-C(24)-H(24C) 109.5 C(39)-C(25)-Sn(2) 127.2(3) Sn(1)-C(2)-H(2A) 109.5 F(15)-C(38)-C(33) 119.9(5) Sn(1)-C(2)-H(2B) 109.5 F(15)-C(38)-C(37) 117.8(6) H(2A)-C(2)-H(2B) 109.5 C(33)-C(38)-C(37) 122.3(6) Sn(1)-C(2)-H(2C) 109.5 F(16)-C(40)-C(41) 117.4(5) H(2A)-C(2)-H(2C) 109.5 F(16)-C(40)-C(39) 119.7(5) H(2B)-C(2)-H(2C) 109.5 ______Symmetry transformations used to generate equivalent atoms:

185 Table A22. Crystal data and structure refinement for 2-8.

Crystallographer Adrian Houghton Empirical formula C22 H6 F14 Sn Formula weight 654.96 Temperature 173(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group P 21 Unit cell dimensions a = 7.8081(4) Å a= 90°. b = 14.4792(9) Å b= 90.521(3)°. c = 9.4551(5) Å g = 90°. Volume 1068.90(10) Å3 Z 2 Density (calculated) 2.035 Mg/m3 Absorption coefficient 1.326 mm-1 F(000) 628 Crystal size 0.10 x 0.08 x 0.06 mm3 Theta range for data collection 2.57 to 27.46°. Index ranges -10<=h<=10, -18<=k<=13, -12<=l<=12 Reflections collected 3452 Independent reflections 3452 [R(int) = 0.0000] Completeness to theta = 27.46° 98.7 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9247 and 0.8788 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 3452 / 1 / 336 Goodness-of-fit on F2 1.063 Final R indices [I>2sigma(I)] R1 = 0.0236, wR2 = 0.0596 R indices (all data) R1 = 0.0242, wR2 = 0.0604 Absolute structure parameter 0.006(19) Largest diff. peak and hole 0.770 and -0.471 e.Å-3

Table A23. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 2-8. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ______x y z U(eq) ______Sn(1) 4654(1) 13236(1) -4172(1) 27(1) F(5) 2386(3) 12082(2) 607(3) 44(1) F(11) 4626(4) 15726(2) 1690(2) 47(1) F(1) 3656(3) 11223(2) -5907(2) 45(1) F(4) -464(3) 11664(2) -1376(3) 36(1) F(2) 1097(4) 10019(2) -5378(3) 49(1) F(12) 3996(3) 17250(2) 120(3) 48(1) F(13) 3167(4) 17081(2) -2661(3) 49(1) F(7) -1719(4) 13847(2) 2954(3) 51(1) F(14) 2787(3) 15402(2) -3816(2) 41(1) F(8) -2154(3) 14903(2) 614(3) 50(1) F(10) 4365(3) 14040(2) 523(2) 38(1) F(9) -364(4) 14541(2) -1728(3) 39(1) F(6) 565(4) 12436(2) 2943(3) 53(1)

186 F(3) -936(3) 10277(2) -3103(3) 43(1) C(3) 3282(5) 13751(3) -2359(3) 27(1) C(4) 2145(4) 13129(3) -1914(3) 27(1) C(6) 2924(5) 12105(3) -3915(4) 29(1) C(5) 1886(4) 12259(3) -2734(4) 26(1) C(12) 1269(5) 12781(3) 584(4) 33(1) C(11) 1080(4) 13297(4) -631(3) 27(1) C(9) 339(5) 10866(3) -3367(4) 33(1) C(14) -830(5) 13662(3) 1785(4) 36(1) C(18) 4003(5) 14779(3) -285(4) 30(1) C(17) 3520(5) 14657(3) -1686(4) 28(1) C(19) 4167(5) 15636(3) 329(4) 34(1) C(1) 4234(6) 13944(4) -6089(4) 44(1) C(13) 337(5) 12956(3) 1786(4) 36(1) C(16) -105(5) 14016(3) -596(4) 30(1) C(20) 3868(5) 16412(3) -464(5) 36(1) C(21) 3433(5) 16324(3) -1876(4) 34(1) C(22) 3251(5) 15464(3) -2459(4) 32(1) C(7) 2661(5) 11363(3) -4763(4) 33(1) C(2) 7223(5) 12881(4) -3689(5) 43(1) C(8) 1366(5) 10736(3) -4525(4) 35(1) C(15) -1044(5) 14194(3) 609(4) 34(1) C(10) 613(5) 11612(3) -2483(4) 29(1)

Table A24. Bond lengths [Å] and angles [°] for 2-8. ______Sn(1)-C(1) 2.106(4) C(6)-C(5) 1.403(5) Sn(1)-C(2) 2.116(4) C(5)-C(10) 1.388(5) Sn(1)-C(6) 2.138(4) C(12)-C(11) 1.377(5) Sn(1)-C(3) 2.162(3) C(12)-C(13) 1.379(5) F(5)-C(12) 1.336(5) C(11)-C(16) 1.394(6) F(11)-C(19) 1.339(5) C(9)-C(8) 1.376(6) F(1)-C(7) 1.353(4) C(9)-C(10) 1.381(5) F(4)-C(10) 1.351(4) C(14)-C(15) 1.362(6) F(2)-C(8) 1.330(5) C(14)-C(13) 1.370(6) F(12)-C(20) 1.336(5) C(18)-C(19) 1.376(6) F(13)-C(21) 1.338(5) C(18)-C(17) 1.385(5) F(7)-C(14) 1.338(4) C(17)-C(22) 1.394(5) F(14)-C(22) 1.333(4) C(19)-C(20) 1.369(6) F(8)-C(15) 1.344(5) C(1)-H(1A) 0.9800 F(10)-C(18) 1.343(4) C(1)-H(1B) 0.9800 F(9)-C(16) 1.326(5) C(1)-H(1C) 0.9800 F(6)-C(13) 1.338(5) C(16)-C(15) 1.385(5) F(3)-C(9) 1.336(4) C(20)-C(21) 1.381(6) C(3)-C(4) 1.335(5) C(21)-C(22) 1.369(6) C(3)-C(17) 1.469(5) C(7)-C(8) 1.379(6) C(4)-C(5) 1.493(6) C(2)-H(2A) 0.9800 C(4)-C(11) 1.496(4) C(2)-H(2B) 0.9800 C(6)-C(7) 1.355(6) C(2)-H(2C) 0.9800

C(1)-Sn(1)-C(2) 116.35(18) C(6)-Sn(1)-C(3) 81.71(14) C(1)-Sn(1)-C(6) 112.14(17) C(4)-C(3)-C(17) 123.1(3) C(2)-Sn(1)-C(6) 112.85(16) C(4)-C(3)-Sn(1) 110.7(3) C(1)-Sn(1)-C(3) 116.09(16) C(17)-C(3)-Sn(1) 126.2(2) C(2)-Sn(1)-C(3) 112.86(15) C(3)-C(4)-C(5) 119.5(3)

187 C(3)-C(4)-C(11) 121.5(4) H(1B)-C(1)-H(1C) 109.5 C(5)-C(4)-C(11) 119.0(4) F(6)-C(13)-C(14) 120.2(3) C(7)-C(6)-C(5) 120.7(4) F(6)-C(13)-C(12) 120.2(4) C(7)-C(6)-Sn(1) 129.2(3) C(14)-C(13)-C(12) 119.5(4) C(5)-C(6)-Sn(1) 109.8(3) F(9)-C(16)-C(15) 118.6(4) C(10)-C(5)-C(6) 116.7(3) F(9)-C(16)-C(11) 120.4(3) C(10)-C(5)-C(4) 125.1(3) C(15)-C(16)-C(11) 121.0(3) C(6)-C(5)-C(4) 118.1(3) F(12)-C(20)-C(19) 120.4(4) F(5)-C(12)-C(11) 119.3(3) F(12)-C(20)-C(21) 120.0(4) F(5)-C(12)-C(13) 118.4(3) C(19)-C(20)-C(21) 119.6(4) C(11)-C(12)-C(13) 122.3(4) F(13)-C(21)-C(22) 120.4(3) C(12)-C(11)-C(16) 116.9(3) F(13)-C(21)-C(20) 119.8(4) C(12)-C(11)-C(4) 122.1(4) C(22)-C(21)-C(20) 119.8(4) C(16)-C(11)-C(4) 121.0(4) F(14)-C(22)-C(21) 118.4(3) F(3)-C(9)-C(8) 120.1(4) F(14)-C(22)-C(17) 119.1(4) F(3)-C(9)-C(10) 119.8(3) C(21)-C(22)-C(17) 122.5(3) C(8)-C(9)-C(10) 120.0(4) F(1)-C(7)-C(6) 120.5(4) F(7)-C(14)-C(15) 120.1(4) F(1)-C(7)-C(8) 117.3(3) F(7)-C(14)-C(13) 119.9(4) C(6)-C(7)-C(8) 122.2(4) C(15)-C(14)-C(13) 119.9(3) Sn(1)-C(2)-H(2A) 109.5 F(10)-C(18)-C(19) 117.4(3) Sn(1)-C(2)-H(2B) 109.5 F(10)-C(18)-C(17) 119.7(3) H(2A)-C(2)-H(2B) 109.5 C(19)-C(18)-C(17) 122.8(4) Sn(1)-C(2)-H(2C) 109.5 C(18)-C(17)-C(22) 115.6(3) H(2A)-C(2)-H(2C) 109.5 C(18)-C(17)-C(3) 124.1(3) H(2B)-C(2)-H(2C) 109.5 C(22)-C(17)-C(3) 120.2(3) F(2)-C(8)-C(9) 119.9(4) F(11)-C(19)-C(20) 119.3(4) F(2)-C(8)-C(7) 121.8(4) F(11)-C(19)-C(18) 121.0(4) C(9)-C(8)-C(7) 118.2(4) C(20)-C(19)-C(18) 119.6(4) F(8)-C(15)-C(14) 120.2(4) Sn(1)-C(1)-H(1A) 109.5 F(8)-C(15)-C(16) 119.4(4) Sn(1)-C(1)-H(1B) 109.5 C(14)-C(15)-C(16) 120.3(4) H(1A)-C(1)-H(1B) 109.5 F(4)-C(10)-C(9) 114.7(3) Sn(1)-C(1)-H(1C) 109.5 F(4)-C(10)-C(5) 123.1(3) H(1A)-C(1)-H(1C) 109.5 C(9)-C(10)-C(5) 122.1(3) ______Symmetry transformations used to generate equivalent atoms:

Table A25. Crystal data and structure refinement for 2-9CH3.

Crystallographer Adrian Houghton Empirical formula C32 H28 Zr Formula weight 503.76 Temperature 173(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group P 21/c Unit cell dimensions a = 7.7070(3) Å a= 90°. b = 30.7970(12) Å b= 93.0900(10)°. c = 10.2530(4) Å g = 90°. Volume 2430.04(16) Å3 Z 4 Density (calculated) 1.377 Mg/m3 Absorption coefficient 0.470 mm-1

188 F(000) 1040 Crystal size 0.08 x 0.06 x 0.04 mm3 Theta range for data collection 2.10 to 27.49°. Index ranges -10<=h<=10, -39<=k<=39, -13<=l<=13 Reflections collected 9648 Independent reflections 5362 [R(int) = 0.0364] Completeness to theta = 27.49° 96.4 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9814 and 0.9634 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5362 / 0 / 213 Goodness-of-fit on F2 1.163 Final R indices [I>2sigma(I)] R1 = 0.0540, wR2 = 0.1014 R indices (all data) R1 = 0.0680, wR2 = 0.1086 Largest diff. peak and hole 0.530 and -0.525 e.Å-3

Table A26. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103)for 2- 9CH3. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ______x y z U(eq) ______Zr(1) 7280(1) 1665(1) 5670(1) 23(1) C(16) 10060(4) 953(1) 7211(3) 26(1) C(9) 8606(4) 1131(1) 9676(3) 25(1) C(8) 5445(1) 1658(1) 9683(1) 30(1) C(4) 5714(1) 1854(1) 7395(1) 24(1) C(2) 7807(1) 1313(1) 8435(1) 25(1) C(29) 5784(1) 972(1) 4968(1) 35(1) C(17) 11608(1) 1041(1) 7922(1) 31(1) C(1) 8505(1) 1233(1) 7263(1) 25(1) C(7) 4067(1) 1940(1) 9781(1) 32(1) C(23) 8143(1) 2364(1) 4664(1) 33(1) C(25) 9609(1) 2177(1) 6551(1) 38(1) C(3) 6303(1) 1614(1) 8514(1) 24(1) C(5) 4336(1) 2140(1) 7538(1) 30(1) C(13) 9519(1) 523(1) 11025(1) 35(1) C(6) 3510(1) 2182(1) 8708(1) 33(1) C(11) 10545(1) 1235(1) 11596(1) 33(1) C(10) 9573(1) 1402(1) 10538(1) 30(1) C(30) 4472(1) 1274(1) 5140(1) 32(1) C(14) 8574(1) 691(1) 9949(1) 32(1) C(12) 10553(1) 789(1) 11850(1) 33(1) C(31) 4573(1) 1605(1) 4205(1) 38(1) C(18) 13015(1) 760(1) 7933(1) 34(1) C(19) 12949(1) 378(1) 7213(1) 33(1) C(24) 8276(1) 2437(1) 6010(1) 34(1) C(27) 9411(1) 2060(1) 4361(1) 36(1) C(28) 6740(1) 1114(1) 3897(1) 44(1) C(21) 10037(1) 578(1) 6439(1) 32(1) C(20) 11438(1) 297(1) 6450(1) 37(1) C(22) 14460(1) 65(1) 7264(1) 46(1) C(26) 10335(1) 1944(1) 5549(1) 44(1) C(32) 5969(1) 1499(1) 3424(1) 50(1)

189 C(15) 11668(1) 608(1) 12958(1) 48(1)

Table A27. Bond lengths [Å] and angles [°] for 2-9CH3. ______Zr(1)-C(4) 2.2697 C(25)-H(25) 0.9500 Zr(1)-C(1) 2.2729 C(5)-C(6) 1.3943 Zr(1)-C(27) 2.4935 C(5)-H(5) 0.9500 Zr(1)-C(23) 2.4936 C(13)-C(14) 1.3880 Zr(1)-C(28) 2.5056 C(13)-C(12) 1.3960 Zr(1)-C(30) 2.5103 C(13)-H(13) 0.9500 Zr(1)-C(31) 2.5108 C(6)-H(6) 0.9500 Zr(1)-C(29) 2.5139 C(11)-C(10) 1.3828 Zr(1)-C(26) 2.5156 C(11)-C(12) 1.3969 Zr(1)-C(32) 2.5165 C(11)-H(11) 0.9500 Zr(1)-C(24) 2.5176 C(10)-H(10) 0.9500 Zr(1)-C(25) 2.5206 C(30)-C(31) 1.4040 C(16)-C(17) 1.391(3) C(30)-H(30) 0.9500 C(16)-C(21) 1.399(4) C(14)-H(14) 0.9500 C(16)-C(1) 1.481(3) C(12)-C(15) 1.4954 C(9)-C(14) 1.382(4) C(31)-C(32) 1.4137 C(9)-C(10) 1.400(4) C(31)-H(31) 0.9500 C(9)-C(2) 1.493(3) C(18)-C(19) 1.3895 C(8)-C(7) 1.3809 C(18)-H(18) 0.9500 C(8)-C(3) 1.4067 C(19)-C(20) 1.3901 C(8)-H(8) 0.9500 C(19)-C(22) 1.5085 C(4)-C(5) 1.3940 C(24)-H(24) 0.9500 C(4)-C(3) 1.4183 C(27)-C(26) 1.4232 C(2)-C(1) 1.3655 C(27)-H(27) 0.9500 C(2)-C(3) 1.4880 C(28)-C(32) 1.4008 C(29)-C(30) 1.3922 C(28)-H(28) 0.9500 C(29)-C(28) 1.4246 C(21)-C(20) 1.3842 C(29)-H(29) 0.9500 C(21)-H(21) 0.9500 C(17)-C(18) 1.3862 C(20)-H(20) 0.9500 C(17)-H(17) 0.9500 C(22)-H(22A) 0.9800 C(7)-C(6) 1.3782 C(22)-H(22B) 0.9800 C(7)-H(7) 0.9500 C(22)-H(22C) 0.9800 C(23)-C(24) 1.3962 C(26)-H(26) 0.9500 C(23)-C(27) 1.4005 C(32)-H(32) 0.9500 C(23)-H(23) 0.9500 C(15)-H(15A) 0.9800 C(25)-C(24) 1.3934 C(15)-H(15B) 0.9800 C(25)-C(26) 1.3947 C(15)-H(15C) 0.9800

C(4)-Zr(1)-C(1) 78.9 C(23)-Zr(1)-C(30) 124.8 C(4)-Zr(1)-C(27) 133.5 C(28)-Zr(1)-C(30) 53.9 C(1)-Zr(1)-C(27) 114.4 C(4)-Zr(1)-C(31) 91.5 C(4)-Zr(1)-C(23) 105.4 C(1)-Zr(1)-C(31) 133.3 C(1)-Zr(1)-C(23) 133.9 C(27)-Zr(1)-C(31) 105.3 C(27)-Zr(1)-C(23) 32.6 C(23)-Zr(1)-C(31) 92.8 C(4)-Zr(1)-C(28) 131.6 C(28)-Zr(1)-C(31) 54.3 C(1)-Zr(1)-C(28) 99.9 C(30)-Zr(1)-C(31) 32.5 C(27)-Zr(1)-C(28) 91.6 C(4)-Zr(1)-C(29) 100.7 C(23)-Zr(1)-C(28) 108.8 C(1)-Zr(1)-C(29) 82.8 C(4)-Zr(1)-C(30) 78.6 C(27)-Zr(1)-C(29) 124.5 C(1)-Zr(1)-C(30) 101.2 C(23)-Zr(1)-C(29) 138.1 C(27)-Zr(1)-C(30) 134.7 C(28)-Zr(1)-C(29) 33.0

190 C(30)-Zr(1)-C(29) 32.2 C(30)-C(29)-Zr(1) 73.8 C(31)-Zr(1)-C(29) 54.0 C(28)-C(29)-Zr(1) 73.2 C(4)-Zr(1)-C(26) 119.3 C(30)-C(29)-H(29) 126.2 C(1)-Zr(1)-C(26) 83.2 C(28)-C(29)-H(29) 126.2 C(27)-Zr(1)-C(26) 33.0 Zr(1)-C(29)-H(29) 118.8 C(23)-Zr(1)-C(26) 54.1 C(18)-C(17)-C(16) 122.04(15) C(28)-Zr(1)-C(26) 108.4 C(18)-C(17)-H(17) 119.0 C(30)-Zr(1)-C(26) 162.1 C(16)-C(17)-H(17) 119.0 C(31)-Zr(1)-C(26) 138.2 C(2)-C(1)-C(16) 119.72(13) C(29)-Zr(1)-C(26) 133.8 C(2)-C(1)-Zr(1) 111.0 C(4)-Zr(1)-C(32) 124.1 C(16)-C(1)-Zr(1) 128.41(14) C(1)-Zr(1)-C(32) 132.0 C(6)-C(7)-C(8) 119.4 C(27)-Zr(1)-C(32) 81.4 C(6)-C(7)-H(7) 120.3 C(23)-Zr(1)-C(32) 84.3 C(8)-C(7)-H(7) 120.3 C(28)-Zr(1)-C(32) 32.4 C(24)-C(23)-C(27) 108.2 C(30)-Zr(1)-C(32) 53.5 C(24)-C(23)-Zr(1) 74.8 C(31)-Zr(1)-C(32) 32.7 C(27)-C(23)-Zr(1) 73.7 C(29)-Zr(1)-C(32) 53.8 C(24)-C(23)-H(23) 125.9 C(26)-Zr(1)-C(32) 110.8 C(27)-C(23)-H(23) 125.9 C(4)-Zr(1)-C(24) 79.7 Zr(1)-C(23)-H(23) 117.6 C(1)-Zr(1)-C(24) 110.0 C(24)-C(25)-C(26) 108.6 C(27)-Zr(1)-C(24) 53.8 C(24)-C(25)-Zr(1) 73.8 C(23)-Zr(1)-C(24) 32.4 C(26)-C(25)-Zr(1) 73.7 C(28)-Zr(1)-C(24) 141.1 C(24)-C(25)-H(25) 125.7 C(30)-Zr(1)-C(24) 137.4 C(26)-C(25)-H(25) 125.7 C(31)-Zr(1)-C(24) 113.0 Zr(1)-C(25)-H(25) 118.6 C(29)-Zr(1)-C(24) 166.9 C(8)-C(3)-C(4) 119.6 C(26)-Zr(1)-C(24) 53.5 C(8)-C(3)-C(2) 120.6 C(32)-Zr(1)-C(24) 115.1 C(4)-C(3)-C(2) 119.8 C(4)-Zr(1)-C(25) 87.6 C(4)-C(5)-C(6) 122.4 C(1)-Zr(1)-C(25) 81.3 C(4)-C(5)-H(5) 118.8 C(27)-Zr(1)-C(25) 53.9 C(6)-C(5)-H(5) 118.8 C(23)-Zr(1)-C(25) 53.6 C(14)-C(13)-C(12) 121.4 C(28)-Zr(1)-C(25) 140.5 C(14)-C(13)-H(13) 119.3 C(30)-Zr(1)-C(25) 165.2 C(12)-C(13)-H(13) 119.3 C(31)-Zr(1)-C(25) 144.4 C(7)-C(6)-C(5) 119.9 C(29)-Zr(1)-C(25) 160.3 C(7)-C(6)-H(6) 120.0 C(26)-Zr(1)-C(25) 32.2 C(5)-C(6)-H(6) 120.0 C(32)-Zr(1)-C(25) 134.3 C(10)-C(11)-C(12) 120.5 C(24)-Zr(1)-C(25) 32.1 C(10)-C(11)-H(11) 119.8 C(17)-C(16)-C(21) 116.3(2) C(12)-C(11)-H(11) 119.8 C(17)-C(16)-C(1) 122.7(2) C(11)-C(10)-C(9) 121.41(14) C(21)-C(16)-C(1) 121.1(2) C(11)-C(10)-H(10) 119.3 C(14)-C(9)-C(10) 118.0(2) C(9)-C(10)-H(10) 119.3 C(14)-C(9)-C(2) 122.0(2) C(29)-C(30)-C(31) 109.4 C(10)-C(9)-C(2) 119.6(2) C(29)-C(30)-Zr(1) 74.1 C(7)-C(8)-C(3) 121.5 C(31)-C(30)-Zr(1) 73.8 C(7)-C(8)-H(8) 119.3 C(29)-C(30)-H(30) 125.3 C(3)-C(8)-H(8) 119.3 C(31)-C(30)-H(30) 125.3 C(5)-C(4)-C(3) 117.2 Zr(1)-C(30)-H(30) 118.6 C(5)-C(4)-Zr(1) 133.1 C(9)-C(14)-C(13) 120.78(14) C(3)-C(4)-Zr(1) 109.7 C(9)-C(14)-H(14) 119.6 C(1)-C(2)-C(3) 120.3 C(13)-C(14)-H(14) 119.6 C(1)-C(2)-C(9) 121.17(13) C(13)-C(12)-C(11) 117.8 C(3)-C(2)-C(9) 118.34(13) C(13)-C(12)-C(15) 121.8 C(30)-C(29)-C(28) 107.5 C(11)-C(12)-C(15) 120.3 191 C(30)-C(31)-C(32) 106.9 C(20)-C(21)-C(16) 121.67(14) C(30)-C(31)-Zr(1) 73.7 C(20)-C(21)-H(21) 119.2 C(32)-C(31)-Zr(1) 73.9 C(16)-C(21)-H(21) 119.2 C(30)-C(31)-H(31) 126.6 C(21)-C(20)-C(19) 121.5 C(32)-C(31)-H(31) 126.6 C(21)-C(20)-H(20) 119.3 Zr(1)-C(31)-H(31) 117.9 C(19)-C(20)-H(20) 119.3 C(17)-C(18)-C(19) 121.2 C(19)-C(22)-H(22A) 109.5 C(17)-C(18)-H(18) 119.4 C(19)-C(22)-H(22B) 109.5 C(19)-C(18)-H(18) 119.4 H(22A)-C(22)-H(22B) 109.5 C(18)-C(19)-C(20) 117.1 C(19)-C(22)-H(22C) 109.5 C(18)-C(19)-C(22) 121.1 H(22A)-C(22)-H(22C) 109.5 C(20)-C(19)-C(22) 121.8 H(22B)-C(22)-H(22C) 109.5 C(25)-C(24)-C(23) 108.3 C(25)-C(26)-C(27) 107.4 C(25)-C(24)-Zr(1) 74.1 C(25)-C(26)-Zr(1) 74.1 C(23)-C(24)-Zr(1) 72.9 C(27)-C(26)-Zr(1) 72.6 C(25)-C(24)-H(24) 125.8 C(25)-C(26)-H(26) 126.3 C(23)-C(24)-H(24) 125.8 C(27)-C(26)-H(26) 126.3 Zr(1)-C(24)-H(24) 119.1 Zr(1)-C(26)-H(26) 118.9 C(23)-C(27)-C(26) 107.5 C(28)-C(32)-C(31) 108.8 C(23)-C(27)-Zr(1) 73.7 C(28)-C(32)-Zr(1) 73.4 C(26)-C(27)-Zr(1) 74.3 C(31)-C(32)-Zr(1) 73.4 C(23)-C(27)-H(27) 126.3 C(28)-C(32)-H(32) 125.6 C(26)-C(27)-H(27) 126.3 C(31)-C(32)-H(32) 125.6 Zr(1)-C(27)-H(27) 117.7 Zr(1)-C(32)-H(32) 119.4 C(32)-C(28)-C(29) 107.4 C(12)-C(15)-H(15A) 109.5 C(32)-C(28)-Zr(1) 74.2 C(12)-C(15)-H(15B) 109.5 C(29)-C(28)-Zr(1) 73.8 H(15A)-C(15)-H(15B) 109.5 C(32)-C(28)-H(28) 126.3 C(12)-C(15)-H(15C) 109.5 C(29)-C(28)-H(28) 126.3 H(15A)-C(15)-H(15C) 109.5 Zr(1)-C(28)-H(28) 117.7 H(15B)-C(15)-H(15C) 109.5 ______Symmetry transformations used to generate equivalent atoms:

Table A28. Crystal data and structure refinement for 2-9C6F5.

Crystallographer Adrian Houghton Empirical formula C30 H14 F10 Zr Formula weight 655.63 Temperature 173(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group C 2/c Unit cell dimensions a = 27.8330(11) Å a= 90°. b = 14.9090(4) Å b= 120.449(2)°. c = 15.8230(7) Å g = 90°. Volume 5660.4(4) Å3 Z 8 Density (calculated) 1.539 Mg/m3 Absorption coefficient 0.472 mm-1 F(000) 2592 Crystal size 0.12 x 0.08 x 0.06 mm3 Theta range for data collection 2.47 to 27.74°. Index ranges -36<=h<=36, -19<=k<=19, -20<=l<=20 Reflections collected 12500

192 Independent reflections 6579 [R(int) = 0.0474] Completeness to theta = 27.74° 98.6 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9722 and 0.9455 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 6579 / 0 / 289 Goodness-of-fit on F2 1.051 Final R indices [I>2sigma(I)] R1 = 0.0793, wR2 = 0.1826 R indices (all data) R1 = 0.1127, wR2 = 0.2010 Largest diff. peak and hole 0.999 and -0.461 e.Å-3

Table A29. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 2- ij 9C6F5. U(eq) is defined as one third of the trace of the orthogonalized U tensor. ______x y z U(eq) ______Zr(1) 2237(1) 2623(1) 2008(1) 41(1) F(36) 1041(1) 3446(2) -1664(2) 54(1) F(32) 1597(1) 5841(2) 562(2) 54(1) F(37) 840(1) 4394(2) 972(3) 57(1) F(33) 983(2) 6953(2) -909(3) 61(1) F(34) 396(1) 6331(2) -2765(3) 59(1) F(35) 395(2) 4553(3) -3109(2) 63(1) F(38) -253(2) 4126(3) 192(3) 69(1) F(41) 932(2) 1885(3) -728(3) 72(1) C(11) 701(2) 5768(4) -2024(4) 43(1) C(13) 1036(2) 4306(4) -1443(4) 40(1) C(8) 1357(2) 4603(3) -492(4) 38(1) C(9) 1316(2) 5502(4) -340(4) 41(1) C(5) 3121(1) 5048(1) 991(1) 55(2) C(7) 2341(1) 4200(1) 843(1) 42(1) C(10) 997(1) 6084(1) -1118(1) 44(1) C(14) 1740(1) 4003(1) 342(1) 38(1) F(39) -767(1) 2760(1) -1061(1) 86(1) C(6) 2552(1) 4869(1) 503(1) 47(1) C(12) 709(1) 4864(1) -2214(1) 47(1) C(16) 937(1) 3165(1) 167(1) 41(1) C(15) 1545(1) 3311(1) 639(1) 40(1) C(17) 654(1) 2448(1) -486(1) 50(1) C(2) 2697(1) 3685(1) 1672(1) 43(1) C(21) 608(1) 3697(1) 363(1) 45(1) C(4) 3468(1) 4537(1) 1775(1) 60(2) F(40) -164(1) 1630(1) -1497(1) 94(2) C(3) 3265(1) 3872(1) 2123(1) 59(2) C(29) 1964(1) 1104(1) 1274(1) 58(2) C(31) 2719(1) 1736(1) 1329(1) 56(2) C(30) 2158(1) 1570(1) 726(1) 57(2) C(28) 2408(1) 982(1) 2207(1) 59(2) C(18) 93(1) 2306(1) -916(1) 63(2) C(27) 2891(1) 1385(1) 2263(1) 59(2) C(19) -208(1) 2906(1) -639(1) 63(2) C(23) 1970(1) 3797(1) 2843(1) 67(2) C(20) 34(1) 3573(1) -17(1) 53(1) C(22) 2560(1) 3666(1) 3466(1) 72(2)

193 C(26) 2640(1) 2793(1) 3818(1) 85(3) C(25) 2096(1) 2355(1) 3430(1) 100(4) C(24) 1716(1) 2999(1) 2849(1) 82(2)

Table A30. Bond lengths [Å] and angles [°] for 2-9C6F5. ______Zr(1)-C(2) 2.2606(13) F(39)-C(19) 1.3630 Zr(1)-C(15) 2.2859(13) C(6)-H(6) 0.9600 Zr(1)-C(27) 2.4772(12) C(16)-C(21) 1.3611 Zr(1)-C(24) 2.4799(13) C(16)-C(17) 1.4166 Zr(1)-C(28) 2.4829(13) C(16)-C(15) 1.4798 Zr(1)-C(29) 2.4830(13) C(17)-C(18) 1.3670 Zr(1)-C(31) 2.4832(12) C(2)-C(3) 1.3943 Zr(1)-C(30) 2.4852(12) C(21)-C(20) 1.4037 Zr(1)-C(26) 2.5035(13) C(4)-C(3) 1.3875 Zr(1)-C(25) 2.5059(13) C(4)-H(4) 0.9600 Zr(1)-C(23) 2.5209(12) F(40)-C(18) 1.3054 Zr(1)-C(22) 2.5388(13) C(3)-H(3) 0.9600 F(36)-C(13) 1.331(6) C(29)-C(28) 1.3748 F(32)-C(9) 1.332(6) C(29)-C(30) 1.4135 F(37)-C(21) 1.340(4) C(29)-H(29) 0.9500 F(33)-C(10) 1.344(3) C(31)-C(30) 1.3788 F(34)-C(11) 1.339(6) C(31)-C(27) 1.4037 F(35)-C(12) 1.315(3) C(31)-H(31) 0.9500 F(38)-C(20) 1.303(4) C(30)-H(30) 0.9500 F(41)-C(17) 1.323(4) C(28)-C(27) 1.4343 C(11)-C(10) 1.326(6) C(28)-H(28) 0.9500 C(11)-C(12) 1.383(6) C(18)-C(19) 1.4373 C(13)-C(12) 1.372(6) C(27)-H(27) 0.9500 C(13)-C(8) 1.378(7) C(19)-C(20) 1.3201 C(8)-C(9) 1.376(7) C(23)-C(24) 1.3853 C(8)-C(14) 1.501(5) C(23)-C(22) 1.4372 C(9)-C(10) 1.397(5) C(23)-H(23) 0.9500 C(5)-C(4) 1.3551 C(22)-C(26) 1.3874 C(5)-C(6) 1.3909 C(22)-H(22) 0.9500 C(5)-H(5) 0.9600 C(26)-C(25) 1.4678 C(7)-C(6) 1.3975 C(26)-H(26) 0.9500 C(7)-C(2) 1.4051 C(25)-C(24) 1.3788 C(7)-C(14) 1.4714 C(25)-H(25) 0.9500 C(14)-C(15) 1.3565 C(24)-H(24) 0.9500

C(2)-Zr(1)-C(15) 76.6 C(28)-Zr(1)-C(29) 32.1 C(2)-Zr(1)-C(27) 95.9 C(2)-Zr(1)-C(31) 77.1 C(15)-Zr(1)-C(27) 133.24(6) C(15)-Zr(1)-C(31) 102.1 C(2)-Zr(1)-C(24) 121.48(5) C(27)-Zr(1)-C(31) 32.9 C(15)-Zr(1)-C(24) 88.0 C(24)-Zr(1)-C(31) 160.80(6) C(27)-Zr(1)-C(24) 131.51(6) C(28)-Zr(1)-C(31) 54.5 C(2)-Zr(1)-C(28) 128.70(5) C(29)-Zr(1)-C(31) 54.3 C(15)-Zr(1)-C(28) 125.27(5) C(2)-Zr(1)-C(30) 94.4 C(27)-Zr(1)-C(28) 33.6 C(15)-Zr(1)-C(30) 80.0 C(24)-Zr(1)-C(28) 106.4 C(27)-Zr(1)-C(30) 54.3 C(2)-Zr(1)-C(29) 127.18(5) C(24)-Zr(1)-C(30) 138.33(6) C(15)-Zr(1)-C(29) 93.1 C(28)-Zr(1)-C(30) 54.0 C(27)-Zr(1)-C(29) 54.7 C(29)-Zr(1)-C(30) 33.1 C(24)-Zr(1)-C(29) 109.5 C(31)-Zr(1)-C(30) 32.2

194 C(2)-Zr(1)-C(26) 102.7 C(11)-C(10)-F(33) 122.0(3) C(15)-Zr(1)-C(26) 135.41(5) C(11)-C(10)-C(9) 120.1(3) C(27)-Zr(1)-C(26) 91.3 F(33)-C(10)-C(9) 117.8(3) C(24)-Zr(1)-C(26) 53.7 C(15)-C(14)-C(7) 120.7 C(28)-Zr(1)-C(26) 90.5 C(15)-C(14)-C(8) 121.8(2) C(29)-Zr(1)-C(26) 118.75(5) C(7)-C(14)-C(8) 117.5(2) C(31)-Zr(1)-C(26) 121.50(5) C(5)-C(6)-C(7) 120.4 C(30)-Zr(1)-C(26) 143.20(6) C(5)-C(6)-H(6) 119.8 C(2)-Zr(1)-C(25) 133.47(6) C(7)-C(6)-H(6) 119.8 C(15)-Zr(1)-C(25) 118.81(5) F(35)-C(12)-C(13) 121.5(3) C(27)-Zr(1)-C(25) 99.9 F(35)-C(12)-C(11) 120.2(3) C(24)-Zr(1)-C(25) 32.1 C(13)-C(12)-C(11) 118.3(3) C(28)-Zr(1)-C(25) 80.6 C(21)-C(16)-C(17) 114.7 C(29)-Zr(1)-C(25) 97.2 C(21)-C(16)-C(15) 121.9 C(31)-Zr(1)-C(25) 132.01(5) C(17)-C(16)-C(15) 123.4 C(30)-Zr(1)-C(25) 130.00(5) C(14)-C(15)-C(16) 119.6 C(26)-Zr(1)-C(25) 34.1 C(14)-C(15)-Zr(1) 112.1 C(2)-Zr(1)-C(23) 89.4 C(16)-C(15)-Zr(1) 127.7 C(15)-Zr(1)-C(23) 81.6 F(41)-C(17)-C(18) 116.56(17) C(27)-Zr(1)-C(23) 145.02(6) F(41)-C(17)-C(16) 119.95(17) C(24)-Zr(1)-C(23) 32.2 C(18)-C(17)-C(16) 123.5 C(28)-Zr(1)-C(23) 134.93(6) C(3)-C(2)-C(7) 116.7 C(29)-Zr(1)-C(23) 140.96(6) C(3)-C(2)-Zr(1) 130.5 C(31)-Zr(1)-C(23) 164.61(6) C(7)-C(2)-Zr(1) 112.8 C(30)-Zr(1)-C(23) 159.80(6) F(37)-C(21)-C(16) 118.80(15) C(26)-Zr(1)-C(23) 53.9 F(37)-C(21)-C(20) 116.02(15) C(25)-Zr(1)-C(23) 54.4 C(16)-C(21)-C(20) 125.2 C(2)-Zr(1)-C(22) 78.7 C(5)-C(4)-C(3) 121.4 C(15)-Zr(1)-C(22) 109.1 C(5)-C(4)-H(4) 120.2 C(27)-Zr(1)-C(22) 114.6 C(3)-C(4)-H(4) 118.4 C(24)-Zr(1)-C(22) 53.6 C(4)-C(3)-C(2) 121.7 C(28)-Zr(1)-C(22) 122.11(5) C(4)-C(3)-H(3) 118.6 C(29)-Zr(1)-C(22) 150.13(6) C(2)-C(3)-H(3) 119.7 C(31)-Zr(1)-C(22) 134.40(5) C(28)-C(29)-C(30) 108.0 C(30)-Zr(1)-C(22) 166.63(6) C(28)-C(29)-Zr(1) 73.9 C(26)-Zr(1)-C(22) 31.9 C(30)-C(29)-Zr(1) 73.6 C(25)-Zr(1)-C(22) 54.9 C(28)-C(29)-H(29) 126.0 C(23)-Zr(1)-C(22) 33.0 C(30)-C(29)-H(29) 126.0 C(10)-C(11)-F(34) 119.7(5) Zr(1)-C(29)-H(29) 118.5 C(10)-C(11)-C(12) 120.8(4) C(30)-C(31)-C(27) 108.8 F(34)-C(11)-C(12) 119.6(4) C(30)-C(31)-Zr(1) 74.0 F(36)-C(13)-C(12) 116.2(4) C(27)-C(31)-Zr(1) 73.3 F(36)-C(13)-C(8) 120.6(5) C(30)-C(31)-H(31) 125.6 C(12)-C(13)-C(8) 123.2(4) C(27)-C(31)-H(31) 125.6 C(9)-C(8)-C(13) 116.0(5) Zr(1)-C(31)-H(31) 118.9 C(9)-C(8)-C(14) 120.8(4) C(31)-C(30)-C(29) 108.4 C(13)-C(8)-C(14) 123.2(4) C(31)-C(30)-Zr(1) 73.8 F(32)-C(9)-C(8) 120.1(5) C(29)-C(30)-Zr(1) 73.4 F(32)-C(9)-C(10) 118.3(4) C(31)-C(30)-H(30) 125.8 C(8)-C(9)-C(10) 121.5(4) C(29)-C(30)-H(30) 125.8 C(4)-C(5)-C(6) 118.9 Zr(1)-C(30)-H(30) 118.9 C(4)-C(5)-H(5) 120.9 C(29)-C(28)-C(27) 108.3 C(6)-C(5)-H(5) 120.2 C(29)-C(28)-Zr(1) 73.9 C(6)-C(7)-C(2) 121.0 C(27)-C(28)-Zr(1) 73.0 C(6)-C(7)-C(14) 121.4 C(29)-C(28)-H(28) 125.8 C(2)-C(7)-C(14) 117.7 C(27)-C(28)-H(28) 125.8 195 Zr(1)-C(28)-H(28) 119.1 C(26)-C(22)-Zr(1) 72.6 F(40)-C(18)-C(17) 123.3 C(23)-C(22)-Zr(1) 72.8 F(40)-C(18)-C(19) 119.9 C(26)-C(22)-H(22) 126.3 C(17)-C(18)-C(19) 116.7 C(23)-C(22)-H(22) 126.3 C(31)-C(27)-C(28) 106.4 Zr(1)-C(22)-H(22) 120.1 C(31)-C(27)-Zr(1) 73.8 C(22)-C(26)-C(25) 109.2 C(28)-C(27)-Zr(1) 73.4 C(22)-C(26)-Zr(1) 75.4 C(31)-C(27)-H(27) 126.8 C(25)-C(26)-Zr(1) 73.1 C(28)-C(27)-H(27) 126.8 C(22)-C(26)-H(26) 125.4 Zr(1)-C(27)-H(27) 118.1 C(25)-C(26)-H(26) 125.4 C(20)-C(19)-F(39) 120.7 Zr(1)-C(26)-H(26) 117.9 C(20)-C(19)-C(18) 122.6 C(24)-C(25)-C(26) 104.4 F(39)-C(19)-C(18) 116.7 C(24)-C(25)-Zr(1) 72.9 C(24)-C(23)-C(22) 106.7 C(26)-C(25)-Zr(1) 72.9 C(24)-C(23)-Zr(1) 72.3 C(24)-C(25)-H(25) 127.8 C(22)-C(23)-Zr(1) 74.2 C(26)-C(25)-H(25) 127.8 C(24)-C(23)-H(23) 126.6 Zr(1)-C(25)-H(25) 118.7 C(22)-C(23)-H(23) 126.6 C(25)-C(24)-C(23) 112.4 Zr(1)-C(23)-H(23) 118.9 C(25)-C(24)-Zr(1) 75.0 F(38)-C(20)-C(19) 121.22(19) C(23)-C(24)-Zr(1) 75.6 F(38)-C(20)-C(21) 121.30(19) C(25)-C(24)-H(24) 123.8 C(19)-C(20)-C(21) 117.4 C(23)-C(24)-H(24) 123.8 C(26)-C(22)-C(23) 107.3 Zr(1)-C(24)-H(24) 117.2 ______Symmetry transformations used to generate equivalent atoms:

Table A31. Crystal data and structure refinement for 2-10.

Crystallographer Adrian Houghton Empirical formula C30 H10 F14 Zr Formula weight 727.60 Temperature 173(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group P 21/n Unit cell dimensions a = 8.4551(3) Å α= 90˚. b = 16.9172(5) Å β= 94.924(2)˚. c = 17.7991(4) Å γ = 90˚. Volume 2536.45(13) Å3 Z 4 Density (calculated) 1.905 Mg/m3 Absorption coefficient 0.559 mm-1 F(000) 1424 Crystal size 0.10 x 0.08 x 0.06 mm3 Theta range for data collection 2.30 to 27.47˚. Index ranges -10<=h<=10, -21<=k<=21, -23<=l<=23 Reflections collected 11213 Independent reflections 5779 [R(int) = 0.0495] Completeness to theta = 27.47˚ 99.6 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9673 and 0.9463 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5779 / 0 / 446

196 Goodness-of-fit on F2 1.134 Final R indices [I>2sigma(I)] R1 = 0.0532, wR2 = 0.0939 R indices (all data) R1 = 0.0799, wR2 = 0.1057 Largest diff. peak and hole 0.446 and -0.489 e.Å-3

Table A32. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 2-10. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ______x y z U(eq) ______Zr(1) -1433(1) 1231(1) 7321(1) 25(1) F(1) -2127(3) 1956(2) 9111(1) 42(1) F(2) -773(3) 3169(2) 9922(1) 49(1) F(3) 1149(3) 4195(2) 9267(1) 48(1) F(4) 1722(3) 4040(2) 7837(1) 42(1) F(5) 1701(3) 892(2) 5890(2) 49(1) F(6) 1738(4) 658(2) 4408(2) 60(1) F(7) 99(4) 1635(2) 3415(1) 59(1) F(8) -1660(3) 2821(2) 3928(1) 49(1) F(9) -1831(3) 3029(1) 5405(1) 38(1) F(10) 3277(3) 2600(2) 6266(2) 45(1) F(11) 4591(3) 3711(2) 5444(2) 54(1) F(12) 3042(4) 5101(2) 5147(1) 54(1) F(13) 270(4) 5388(2) 5750(1) 48(1) F(14) -1040(3) 4274(1) 6576(1) 38(1) C(1) 678(6) 819(3) 8310(3) 43(1) C(2) -593(6) 294(3) 8353(3) 40(1) C(3) -710(6) -158(3) 7694(3) 39(1) C(4) 444(6) 106(3) 7241(3) 40(1) C(5) 1308(5) 713(3) 7621(3) 42(1) C(6) -4253(6) 1033(5) 7495(4) 64(2) C(7) -3943(7) 537(4) 6927(4) 69(2) C(8) -3607(6) 978(3) 6322(3) 50(1) C(9) -3713(5) 1769(3) 6499(3) 41(1) C(10) -4136(6) 1801(4) 7249(3) 50(1) C(11) -172(5) 2071(2) 6543(2) 25(1) C(12) 315(4) 2758(2) 6873(2) 24(1) C(13) 59(4) 2891(2) 7677(2) 26(1) C(14) -916(5) 2344(2) 8023(2) 27(1) C(15) -1184(5) 2466(3) 8762(2) 32(1) C(16) -515(5) 3080(3) 9192(2) 35(1) C(17) 461(5) 3599(2) 8861(2) 31(1) C(18) 746(5) 3507(2) 8114(2) 29(1) C(19) -58(5) 1968(2) 5720(2) 28(1) C(20) 808(5) 1371(2) 5425(2) 35(1) C(21) 860(6) 1249(3) 4659(3) 42(1) C(22) 26(6) 1739(3) 4160(2) 41(1) C(23) -860(5) 2333(3) 4419(2) 35(1) C(24) -908(5) 2440(2) 5178(2) 30(1) C(25) 1062(5) 3395(2) 6439(2) 26(1) C(26) 2502(5) 3283(3) 6140(2) 31(1) C(27) 3194(5) 3844(3) 5715(2) 36(1) C(28) 2425(6) 4549(3) 5575(2) 38(1) C(29) 1002(5) 4692(2) 5877(2) 34(1)

197 C(30) 358(5) 4121(2) 6298(2) 29(1)

Table A33. Bond lengths [Å] and angles [˚] for 2-10. ______Zr(1)-C(14) 2.282(4) C(4)-H(4) 0.92(4) Zr(1)-C(11) 2.307(4) C(5)-H(5) 0.90(4) Zr(1)-C(6) 2.454(5) C(6)-C(7) 1.357(9) Zr(1)-C(10) 2.473(5) C(6)-C(10) 1.377(9) Zr(1)-C(7) 2.474(6) C(6)-H(6) 0.94(5) Zr(1)-C(8) 2.482(5) C(7)-C(8) 1.360(9) Zr(1)-C(2) 2.484(4) C(7)-H(7) 1.00(7) Zr(1)-C(9) 2.490(4) C(8)-C(9) 1.378(7) Zr(1)-C(4) 2.490(4) C(8)-H(8) 0.96(5) Zr(1)-C(5) 2.492(4) C(9)-C(10) 1.413(7) Zr(1)-C(1) 2.496(4) C(9)-H(9) 0.88(5) Zr(1)-C(3) 2.504(4) C(10)-H(10) 0.79(6) F(1)-C(15) 1.361(5) C(11)-C(12) 1.350(5) F(2)-C(16) 1.343(4) C(11)-C(19) 1.487(5) F(3)-C(17) 1.344(4) C(12)-C(13) 1.483(5) F(4)-C(18) 1.344(5) C(12)-C(25) 1.498(5) F(5)-C(20) 1.344(5) C(13)-C(18) 1.397(5) F(6)-C(21) 1.344(5) C(13)-C(14) 1.414(5) F(7)-C(22) 1.343(5) C(14)-C(15) 1.368(5) F(8)-C(23) 1.342(5) C(15)-C(16) 1.383(6) F(9)-C(24) 1.349(5) C(16)-C(17) 1.373(6) F(10)-C(26) 1.338(5) C(17)-C(18) 1.380(5) F(11)-C(27) 1.333(5) C(19)-C(20) 1.377(6) F(12)-C(28) 1.340(5) C(19)-C(24) 1.401(6) F(13)-C(29) 1.341(5) C(20)-C(21) 1.384(6) F(14)-C(30) 1.344(4) C(21)-C(22) 1.366(7) C(1)-C(5) 1.390(7) C(22)-C(23) 1.358(6) C(1)-C(2) 1.402(7) C(23)-C(24) 1.367(6) C(1)-H(1) 0.88(5) C(25)-C(30) 1.378(5) C(2)-C(3) 1.397(7) C(25)-C(26) 1.382(5) C(2)-H(2) 0.89(5) C(26)-C(27) 1.375(6) C(3)-C(4) 1.391(7) C(27)-C(28) 1.371(7) C(3)-H(3) 0.91(5) C(28)-C(29) 1.380(6) C(4)-C(5) 1.400(7) C(29)-C(30) 1.365(6)

C(14)-Zr(1)-C(11) 75.14(14) C(10)-Zr(1)-C(8) 53.57(18) C(14)-Zr(1)-C(6) 100.7(2) C(7)-Zr(1)-C(8) 31.9(2) C(11)-Zr(1)-C(6) 131.60(16) C(14)-Zr(1)-C(2) 95.32(15) C(14)-Zr(1)-C(10) 80.75(17) C(11)-Zr(1)-C(2) 135.98(15) C(11)-Zr(1)-C(10) 101.63(18) C(6)-Zr(1)-C(2) 92.22(18) C(6)-Zr(1)-C(10) 32.4(2) C(10)-Zr(1)-C(2) 119.4(2) C(14)-Zr(1)-C(7) 131.8(2) C(7)-Zr(1)-C(2) 95.18(19) C(11)-Zr(1)-C(7) 123.5(2) C(8)-Zr(1)-C(2) 124.53(19) C(6)-Zr(1)-C(7) 32.0(2) C(14)-Zr(1)-C(9) 97.04(16) C(10)-Zr(1)-C(7) 53.4(2) C(11)-Zr(1)-C(9) 78.30(14) C(14)-Zr(1)-C(8) 129.04(16) C(6)-Zr(1)-C(9) 53.99(17) C(11)-Zr(1)-C(8) 91.64(18) C(10)-Zr(1)-C(9) 33.07(17) C(6)-Zr(1)-C(8) 53.1(2) C(7)-Zr(1)-C(9) 53.47(19)

198 C(8)-Zr(1)-C(9) 32.19(17) C(2)-C(3)-H(3) 125(3) C(2)-Zr(1)-C(9) 145.63(16) Zr(1)-C(3)-H(3) 117(3) C(14)-Zr(1)-C(4) 124.71(15) C(3)-C(4)-C(5) 108.5(5) C(11)-Zr(1)-C(4) 96.15(15) C(3)-C(4)-Zr(1) 74.4(3) C(6)-Zr(1)-C(4) 122.3(2) C(5)-C(4)-Zr(1) 73.7(3) C(10)-Zr(1)-C(4) 152.30(19) C(3)-C(4)-H(4) 123(3) C(7)-Zr(1)-C(4) 99.0(2) C(5)-C(4)-H(4) 128(3) C(8)-Zr(1)-C(4) 105.28(17) Zr(1)-C(4)-H(4) 118(3) C(2)-Zr(1)-C(4) 53.92(17) C(1)-C(5)-C(4) 107.3(5) C(9)-Zr(1)-C(4) 135.29(18) C(1)-C(5)-Zr(1) 74.0(3) C(14)-Zr(1)-C(5) 92.43(15) C(4)-C(5)-Zr(1) 73.6(3) C(11)-Zr(1)-C(5) 82.88(15) C(1)-C(5)-H(5) 130(3) C(6)-Zr(1)-C(5) 145.16(19) C(4)-C(5)-H(5) 122(3) C(10)-Zr(1)-C(5) 170.45(18) Zr(1)-C(5)-H(5) 120(3) C(7)-Zr(1)-C(5) 130.8(2) C(7)-C(6)-C(10) 108.9(5) C(8)-Zr(1)-C(5) 135.27(18) C(7)-C(6)-Zr(1) 74.9(4) C(2)-Zr(1)-C(5) 54.23(17) C(10)-C(6)-Zr(1) 74.6(3) C(9)-Zr(1)-C(5) 155.94(17) C(7)-C(6)-H(6) 127(3) C(4)-Zr(1)-C(5) 32.64(16) C(10)-C(6)-H(6) 124(3) C(14)-Zr(1)-C(1) 75.66(15) Zr(1)-C(6)-H(6) 117(3) C(11)-Zr(1)-C(1) 104.80(16) C(6)-C(7)-C(8) 108.4(6) C(6)-Zr(1)-C(1) 121.11(18) C(6)-C(7)-Zr(1) 73.2(3) C(10)-Zr(1)-C(1) 138.30(18) C(8)-C(7)-Zr(1) 74.4(3) C(7)-Zr(1)-C(1) 127.7(2) C(6)-C(7)-H(7) 120(4) C(8)-Zr(1)-C(1) 153.86(18) C(8)-C(7)-H(7) 131(4) C(2)-Zr(1)-C(1) 32.70(16) Zr(1)-C(7)-H(7) 115(4) C(9)-Zr(1)-C(1) 170.75(18) C(7)-C(8)-C(9) 109.3(6) C(4)-Zr(1)-C(1) 53.59(17) C(7)-C(8)-Zr(1) 73.8(3) C(5)-Zr(1)-C(1) 32.37(16) C(9)-C(8)-Zr(1) 74.2(3) C(14)-Zr(1)-C(3) 126.77(15) C(7)-C(8)-H(8) 121(3) C(11)-Zr(1)-C(3) 128.48(15) C(9)-C(8)-H(8) 130(3) C(6)-Zr(1)-C(3) 93.2(2) Zr(1)-C(8)-H(8) 117(3) C(10)-Zr(1)-C(3) 125.7(2) C(8)-C(9)-C(10) 106.3(5) C(7)-Zr(1)-C(3) 79.25(19) C(8)-C(9)-Zr(1) 73.6(3) C(8)-Zr(1)-C(3) 100.20(18) C(10)-C(9)-Zr(1) 72.8(3) C(2)-Zr(1)-C(3) 32.52(15) C(8)-C(9)-H(9) 132(3) C(9)-Zr(1)-C(3) 131.12(17) C(10)-C(9)-H(9) 121(3) C(4)-Zr(1)-C(3) 32.35(15) Zr(1)-C(9)-H(9) 119(3) C(5)-Zr(1)-C(3) 53.95(16) C(6)-C(10)-C(9) 107.1(5) C(1)-Zr(1)-C(3) 53.66(17) C(6)-C(10)-Zr(1) 73.0(3) C(5)-C(1)-C(2) 108.6(5) C(9)-C(10)-Zr(1) 74.1(3) C(5)-C(1)-Zr(1) 73.7(3) C(6)-C(10)-H(10) 136(5) C(2)-C(1)-Zr(1) 73.2(3) C(9)-C(10)-H(10) 117(5) C(5)-C(1)-H(1) 131(3) Zr(1)-C(10)-H(10) 115(5) C(2)-C(1)-H(1) 120(3) C(12)-C(11)-C(19) 119.1(4) Zr(1)-C(1)-H(1) 120(3) C(12)-C(11)-Zr(1) 114.1(3) C(3)-C(2)-C(1) 107.5(5) C(19)-C(11)-Zr(1) 126.2(3) C(3)-C(2)-Zr(1) 74.5(3) C(11)-C(12)-C(13) 119.1(3) C(1)-C(2)-Zr(1) 74.1(3) C(11)-C(12)-C(25) 121.4(3) C(3)-C(2)-H(2) 125(3) C(13)-C(12)-C(25) 119.5(3) C(1)-C(2)-H(2) 128(3) C(18)-C(13)-C(14) 118.4(4) Zr(1)-C(2)-H(2) 120(3) C(18)-C(13)-C(12) 124.2(4) C(4)-C(3)-C(2) 108.0(4) C(14)-C(13)-C(12) 117.4(3) C(4)-C(3)-Zr(1) 73.3(3) C(15)-C(14)-C(13) 118.1(4) C(2)-C(3)-Zr(1) 73.0(3) C(15)-C(14)-Zr(1) 127.6(3) C(4)-C(3)-H(3) 127(3) C(13)-C(14)-Zr(1) 113.1(3)

199 F(1)-C(15)-C(14) 119.7(4) F(8)-C(23)-C(22) 119.7(4) F(1)-C(15)-C(16) 116.8(4) F(8)-C(23)-C(24) 120.5(4) C(14)-C(15)-C(16) 123.5(4) C(22)-C(23)-C(24) 119.8(4) F(2)-C(16)-C(17) 119.8(4) F(9)-C(24)-C(23) 117.4(4) F(2)-C(16)-C(15) 121.9(4) F(9)-C(24)-C(19) 119.4(4) C(17)-C(16)-C(15) 118.3(4) C(23)-C(24)-C(19) 123.3(4) F(3)-C(17)-C(16) 119.8(4) C(30)-C(25)-C(26) 115.7(4) F(3)-C(17)-C(18) 120.0(4) C(30)-C(25)-C(12) 122.7(4) C(16)-C(17)-C(18) 120.2(4) C(26)-C(25)-C(12) 121.6(4) F(4)-C(18)-C(17) 116.2(4) F(10)-C(26)-C(27) 117.5(4) F(4)-C(18)-C(13) 122.4(4) F(10)-C(26)-C(25) 119.3(4) C(17)-C(18)-C(13) 121.4(4) C(27)-C(26)-C(25) 123.2(4) C(20)-C(19)-C(24) 114.4(4) F(11)-C(27)-C(28) 120.1(4) C(20)-C(19)-C(11) 122.9(4) F(11)-C(27)-C(26) 121.1(4) C(24)-C(19)-C(11) 122.6(4) C(28)-C(27)-C(26) 118.8(4) F(5)-C(20)-C(19) 119.8(4) F(12)-C(28)-C(27) 120.5(4) F(5)-C(20)-C(21) 117.0(4) F(12)-C(28)-C(29) 119.6(4) C(19)-C(20)-C(21) 123.2(4) C(27)-C(28)-C(29) 119.9(4) F(6)-C(21)-C(22) 120.3(4) F(13)-C(29)-C(30) 120.9(4) F(6)-C(21)-C(20) 120.2(4) F(13)-C(29)-C(28) 119.6(4) C(22)-C(21)-C(20) 119.5(4) C(30)-C(29)-C(28) 119.4(4) F(7)-C(22)-C(23) 120.4(4) F(14)-C(30)-C(29) 118.1(4) F(7)-C(22)-C(21) 119.8(4) F(14)-C(30)-C(25) 119.0(4) C(23)-C(22)-C(21) 119.8(4) C(29)-C(30)-C(25) 122.9(4) ______Symmetry transformations used to generate equivalent atoms:

Table A34. Crystal data and structure refinement for 2-11.

Crystallographer Adrian Houghton Empirical formula C20 B Br F14 Formula weight 596.92 Temperature 173(2) K Wavelength 0.71073 Å Crystal system Triclinic Space group P -1 Unit cell dimensions a = 9.0742(3) Å a= 71.095(2)°. b = 10.2272(4) Å b= 79.247(2)°. c = 10.9121(3) Å g = 84.755(2)°. Volume 940.71(5) Å3 Z 2 Density (calculated) 2.107 Mg/m3 Absorption coefficient 2.330 mm-1 F(000) 572 Crystal size 0.10 x 0.08 x 0.06 mm3 Theta range for data collection 3.03 to 27.58°. Index ranges -11<=h<=11, -13<=k<=13, -13<=l<=14 Reflections collected 7922 Independent reflections 4291 [R(int) = 0.0206] Completeness to theta = 27.58° 98.7 % Absorption correction Semi-empirical from equivalents

200 Max. and min. transmission 0.8729 and 0.8004 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 4291 / 0 / 325 Goodness-of-fit on F2 1.081 Final R indices [I>2sigma(I)] R1 = 0.0351, wR2 = 0.0821 R indices (all data) R1 = 0.0420, wR2 = 0.0885 Largest diff. peak and hole 0.575 and -0.419 e.Å-3

Table A35. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 2-11. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ______x y z U(eq) ______Br(1) 9042(1) 1425(1) 10696(1) 36(1) F(9) 3832(2) 1015(2) 8514(2) 32(1) F(4) 1775(2) 2588(2) 12014(2) 36(1) F(5) 2886(2) 4930(2) 9953(2) 35(1) F(14) 7657(2) 195(2) 8622(2) 35(1) F(13) 8887(2) 635(2) 6092(2) 47(1) F(8) 1551(2) 1830(2) 7146(2) 40(1) F(1) 7085(2) 1203(2) 13783(2) 41(1) F(7) -49(2) 4186(2) 7161(2) 43(1) F(6) 621(2) 5730(2) 8573(2) 42(1) F(3) 1926(2) 2149(2) 14518(2) 45(1) F(10) 5778(2) 4802(2) 7573(2) 40(1) F(2) 4579(2) 1511(2) 15417(2) 44(1) C(3) 4405(3) 2246(2) 11516(2) 24(1) B(15) 6974(3) 1829(3) 10764(3) 26(1) C(12) 1082(3) 3788(3) 7841(2) 31(1) C(2) 4638(3) 2488(2) 10071(2) 23(1) C(9) 3407(3) 2935(2) 9300(2) 23(1) C(13) 1898(3) 2595(3) 7829(2) 29(1) F(12) 8572(2) 3162(2) 4293(2) 52(1) C(10) 2562(3) 4139(3) 9274(2) 27(1) C(14) 3052(3) 2187(3) 8540(2) 25(1) F(11) 6956(2) 5211(2) 5049(2) 52(1) C(5) 5820(3) 1605(3) 13283(3) 30(1) C(19) 8125(3) 1655(3) 6460(3) 34(1) C(4) 5793(3) 1869(3) 11976(2) 26(1) C(16) 6522(3) 3743(3) 7238(3) 30(1) C(15) 6687(3) 2482(3) 8190(2) 26(1) C(20) 7500(3) 1456(3) 7755(3) 29(1) C(1) 6087(3) 2255(2) 9590(2) 24(1) C(8) 3122(3) 2295(3) 12377(2) 27(1) C(11) 1412(3) 4572(3) 8563(3) 29(1) C(6) 4521(3) 1725(3) 14145(2) 32(1) C(7) 3182(3) 2051(3) 13701(3) 32(1) C(17) 7134(3) 3966(3) 5932(3) 36(1) C(18) 7952(3) 2927(3) 5548(3) 38(1)

Table A36. Bond lengths [Å] and angles [°] for 2-11. ______Br(1)-B(15) 1.878(3) F(9)-C(14) 1.341(3)

201 F(4)-C(8) 1.334(3) C(2)-C(9) 1.474(3) F(5)-C(10) 1.343(3) C(9)-C(10) 1.385(3) F(14)-C(20) 1.344(3) C(9)-C(14) 1.389(3) F(13)-C(19) 1.328(3) C(13)-C(14) 1.374(4) F(8)-C(13) 1.333(3) F(12)-C(18) 1.332(3) F(1)-C(5) 1.337(3) C(10)-C(11) 1.371(3) F(7)-C(12) 1.335(3) F(11)-C(17) 1.342(3) F(6)-C(11) 1.330(3) C(5)-C(4) 1.368(4) F(3)-C(7) 1.327(3) C(5)-C(6) 1.387(4) F(10)-C(16) 1.340(3) C(19)-C(18) 1.375(4) F(2)-C(6) 1.344(3) C(19)-C(20) 1.377(4) C(3)-C(8) 1.361(4) C(16)-C(17) 1.382(4) C(3)-C(4) 1.417(3) C(16)-C(15) 1.385(4) C(3)-C(2) 1.492(3) C(15)-C(20) 1.386(4) B(15)-C(4) 1.548(4) C(15)-C(1) 1.472(3) B(15)-C(1) 1.562(4) C(8)-C(7) 1.395(4) C(12)-C(13) 1.371(4) C(6)-C(7) 1.365(4) C(12)-C(11) 1.377(4) C(17)-C(18) 1.372(4) C(2)-C(1) 1.352(3)

C(8)-C(3)-C(4) 120.0(2) C(3)-C(4)-B(15) 106.1(2) C(8)-C(3)-C(2) 130.2(2) F(10)-C(16)-C(17) 117.8(2) C(4)-C(3)-C(2) 109.7(2) F(10)-C(16)-C(15) 120.2(2) C(4)-B(15)-C(1) 105.2(2) C(17)-C(16)-C(15) 122.0(3) C(4)-B(15)-Br(1) 127.75(19) C(16)-C(15)-C(20) 116.1(2) C(1)-B(15)-Br(1) 127.0(2) C(16)-C(15)-C(1) 122.2(2) F(7)-C(12)-C(13) 119.9(2) C(20)-C(15)-C(1) 121.7(2) F(7)-C(12)-C(11) 119.7(3) F(14)-C(20)-C(19) 118.0(2) C(13)-C(12)-C(11) 120.3(2) F(14)-C(20)-C(15) 119.0(2) C(1)-C(2)-C(9) 125.8(2) C(19)-C(20)-C(15) 123.0(2) C(1)-C(2)-C(3) 111.7(2) C(2)-C(1)-C(15) 124.6(2) C(9)-C(2)-C(3) 122.5(2) C(2)-C(1)-B(15) 107.4(2) C(10)-C(9)-C(14) 116.5(2) C(15)-C(1)-B(15) 127.9(2) C(10)-C(9)-C(2) 121.7(2) F(4)-C(8)-C(3) 122.9(2) C(14)-C(9)-C(2) 121.8(2) F(4)-C(8)-C(7) 117.0(2) F(8)-C(13)-C(12) 119.8(2) C(3)-C(8)-C(7) 120.1(2) F(8)-C(13)-C(14) 120.6(2) F(6)-C(11)-C(10) 120.6(2) C(12)-C(13)-C(14) 119.6(2) F(6)-C(11)-C(12) 120.3(2) F(5)-C(10)-C(11) 118.3(2) C(10)-C(11)-C(12) 119.1(2) F(5)-C(10)-C(9) 119.2(2) F(2)-C(6)-C(7) 120.0(3) C(11)-C(10)-C(9) 122.6(2) F(2)-C(6)-C(5) 120.0(2) F(9)-C(14)-C(13) 118.4(2) C(7)-C(6)-C(5) 119.9(2) F(9)-C(14)-C(9) 119.6(2) F(3)-C(7)-C(6) 120.6(2) C(13)-C(14)-C(9) 122.0(2) F(3)-C(7)-C(8) 119.2(2) F(1)-C(5)-C(4) 121.6(2) C(6)-C(7)-C(8) 120.1(2) F(1)-C(5)-C(6) 117.5(2) F(11)-C(17)-C(18) 120.3(3) C(4)-C(5)-C(6) 120.9(2) F(11)-C(17)-C(16) 119.7(3) F(13)-C(19)-C(18) 120.2(2) C(18)-C(17)-C(16) 119.9(3) F(13)-C(19)-C(20) 120.7(3) F(12)-C(18)-C(17) 119.6(3) C(18)-C(19)-C(20) 119.1(3) F(12)-C(18)-C(19) 120.5(3) C(5)-C(4)-C(3) 118.8(2) C(17)-C(18)-C(19) 119.9(3) C(5)-C(4)-B(15) 135.1(2) ______Symmetry transformations used to generate equivalent atoms:

202 Table A37. Crystal data and structure refinement for 3-3.

Crystallographer Adrian Houghton Empirical formula C40 H31 B O Formula weight 538.46 Temperature 173(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group P2(1)/c Unit cell dimensions a = 11.9170(3) Å a= 90.000°. b = 19.6110(3) Å b= 119.088(2)°. c = 14.2740(4) Å g = 90.000°. Volume 2915.15(12) Å3 Z 4 Density (calculated) 1.227 Mg/m3 Absorption coefficient 0.071 mm-1 F(000) 1136 Crystal size 0.20 x 0.20 x 0.16 mm3 Theta range for data collection 1.93 to 27.52°. Index ranges -15<=h<=15, -20<=k<=25, -15<=l<=18 Reflections collected 17174 Independent reflections 6669 [R(int) = 0.0455] Completeness to theta = 27.52° 99.4 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.8514 and 0.5561 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 6669 / 0 / 495 Goodness-of-fit on F2 1.161 Final R indices [I>2sigma(I)] R1 = 0.0587, wR2 = 0.1354 R indices (all data) R1 = 0.0838, wR2 = 0.1506 Largest diff. peak and hole 0.249 and -0.251 e.Å-3

Table A38. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 3-3. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ______x y z U(eq) ______O(1) 7026(1) 2543(1) 2694(1) 35(1) C(2) 7877(2) 1845(1) 5062(1) 27(1) C(3) 9127(2) 2129(1) 5253(1) 28(1) C(1) 6771(2) 2139(1) 4303(1) 27(1) C(17) 5488(2) 1981(1) 4188(2) 28(1) C(4) 9236(2) 2811(1) 5171(2) 30(1) C(29) 10221(2) 1652(1) 5557(2) 29(1) C(35) 10255(2) 3204(1) 5119(2) 31(1) C(18) 5293(2) 1963(1) 5074(2) 32(1) C(28) 7037(2) 699(1) 5212(2) 32(1) C(5) 7534(2) 1939(1) 2551(2) 32(1) C(10) 8654(2) 1986(1) 2500(2) 37(1) C(23) 7901(2) 1235(1) 5695(2) 28(1) C(33) 11122(2) 645(1) 5221(2) 38(1) C(22) 4423(2) 1882(1) 3177(2) 34(1)

203 C(19) 4100(2) 1828(1) 4965(2) 39(1) C(30) 11404(2) 1780(1) 6461(2) 37(1) C(6) 6917(2) 1321(1) 2403(2) 36(1) C(20) 3063(2) 1705(1) 3960(2) 42(1) C(11) 6244(2) 3433(1) 3463(2) 30(1) C(24) 8814(2) 1167(1) 6772(2) 33(1) C(14) 5484(2) 4775(1) 3507(2) 41(1) C(12) 6146(2) 3907(1) 2702(2) 35(1) C(34) 10085(2) 1073(1) 4957(2) 31(1) B(1) 6734(2) 2688(1) 3487(2) 30(1) C(9) 9180(2) 1407(1) 2316(2) 42(1) C(27) 7072(2) 130(1) 5791(2) 38(1) C(36) 10369(2) 3897(1) 5377(2) 36(1) C(40) 11067(2) 2942(1) 4764(2) 38(1) C(16) 5957(2) 3654(1) 4254(2) 37(1) C(31) 12432(2) 1346(1) 6730(2) 44(1) C(37) 11279(2) 4300(1) 5314(2) 42(1) C(13) 5768(2) 4573(1) 2724(2) 40(1) C(21) 3233(2) 1735(1) 3075(2) 40(1) C(7) 7459(2) 745(1) 2217(2) 39(1) C(8) 8577(2) 786(1) 2170(2) 41(1) C(32) 12288(2) 782(1) 6101(2) 43(1) C(25) 8839(2) 595(1) 7351(2) 39(1) C(26) 7971(2) 76(1) 6860(2) 41(1) C(15) 5580(2) 4318(1) 4274(2) 45(1) C(39) 11955(2) 3349(1) 4677(2) 47(1) C(38) 12069(2) 4029(1) 4959(2) 47(1)

Table A39. Bond lengths [Å] and angles [°] for 3-3. ______O(1)-B(1) 1.367(3) C(10)-H(31) 0.99(3) O(1)-C(5) 1.389(2) C(23)-C(24) 1.393(3) C(2)-C(1) 1.361(3) C(33)-C(32) 1.373(3) C(2)-C(3) 1.486(3) C(33)-C(34) 1.385(3) C(2)-C(23) 1.491(3) C(33)-H(10) 1.00(2) C(3)-C(4) 1.354(3) C(22)-C(21) 1.384(3) C(3)-C(29) 1.486(3) C(22)-H(21) 1.01(2) C(1)-C(17) 1.488(3) C(19)-C(20) 1.385(3) C(1)-B(1) 1.571(3) C(19)-H(18) 0.99(2) C(17)-C(18) 1.393(3) C(30)-C(31) 1.384(3) C(17)-C(22) 1.396(3) C(30)-H(7) 0.98(2) C(4)-C(35) 1.471(3) C(6)-C(7) 1.390(3) C(4)-H(1) 1.00(2) C(6)-H(27) 1.00(2) C(29)-C(34) 1.384(3) C(20)-C(21) 1.373(3) C(29)-C(30) 1.395(3) C(20)-H(19) 0.99(2) C(35)-C(40) 1.391(3) C(11)-C(12) 1.392(3) C(35)-C(36) 1.397(3) C(11)-C(16) 1.398(3) C(18)-C(19) 1.379(3) C(11)-B(1) 1.568(3) C(18)-H(17) 0.98(2) C(24)-C(25) 1.386(3) C(28)-C(27) 1.378(3) C(24)-H(12) 0.97(2) C(28)-C(23) 1.397(3) C(14)-C(13) 1.374(3) C(28)-H(16) 0.98(2) C(14)-C(15) 1.375(3) C(5)-C(10) 1.375(3) C(14)-H(24) 0.97(2) C(5)-C(6) 1.379(3) C(12)-C(13) 1.388(3) C(10)-C(9) 1.383(3) C(12)-H(26) 0.99(2)

204 C(34)-H(11) 1.00(2) C(37)-H(3) 0.95(2) C(9)-C(8) 1.378(3) C(13)-H(25) 0.96(2) C(9)-H(30) 0.96(2) C(21)-H(20) 0.96(2) C(27)-C(26) 1.377(3) C(7)-C(8) 1.369(3) C(27)-H(15) 0.96(3) C(7)-H(28) 0.97(2) C(36)-C(37) 1.380(3) C(8)-H(29) 0.96(2) C(36)-H(36) 0.9300 C(32)-H(9) 0.98(3) C(40)-C(39) 1.379(3) C(25)-C(26) 1.375(3) C(40)-H(6) 0.97(2) C(25)-H(13) 0.98(3) C(16)-C(15) 1.382(3) C(26)-H(14) 1.00(3) C(16)-H(22) 1.00(2) C(15)-H(23) 1.01(2) C(31)-C(32) 1.382(3) C(39)-C(38) 1.381(3) C(31)-H(8) 0.97(3) C(39)-H(5) 0.94(3) C(37)-C(38) 1.375(3) C(38)-H(4) 0.9300

B(1)-O(1)-C(5) 127.18(15) C(21)-C(22)-H(21) 120.3(13) C(1)-C(2)-C(3) 119.01(17) C(17)-C(22)-H(21) 119.2(13) C(1)-C(2)-C(23) 123.19(17) C(18)-C(19)-C(20) 120.1(2) C(3)-C(2)-C(23) 117.77(16) C(18)-C(19)-H(18) 120.0(14) C(4)-C(3)-C(2) 118.87(17) C(20)-C(19)-H(18) 119.9(15) C(4)-C(3)-C(29) 122.58(18) C(31)-C(30)-C(29) 120.5(2) C(2)-C(3)-C(29) 118.52(16) C(31)-C(30)-H(7) 121.9(13) C(2)-C(1)-C(17) 123.10(17) C(29)-C(30)-H(7) 117.6(13) C(2)-C(1)-B(1) 123.12(17) C(5)-C(6)-C(7) 118.7(2) C(17)-C(1)-B(1) 113.77(16) C(5)-C(6)-H(27) 118.9(13) C(18)-C(17)-C(22) 117.76(18) C(7)-C(6)-H(27) 122.4(13) C(18)-C(17)-C(1) 121.34(17) C(21)-C(20)-C(19) 119.3(2) C(22)-C(17)-C(1) 120.81(17) C(21)-C(20)-H(19) 122.0(13) C(3)-C(4)-C(35) 129.71(19) C(19)-C(20)-H(19) 118.7(13) C(3)-C(4)-H(1) 116.8(13) C(12)-C(11)-C(16) 117.62(19) C(35)-C(4)-H(1) 113.4(13) C(12)-C(11)-B(1) 121.87(18) C(34)-C(29)-C(30) 118.72(18) C(16)-C(11)-B(1) 120.42(18) C(34)-C(29)-C(3) 120.86(17) C(25)-C(24)-C(23) 121.0(2) C(30)-C(29)-C(3) 120.42(18) C(25)-C(24)-H(12) 119.1(13) C(40)-C(35)-C(36) 117.46(19) C(23)-C(24)-H(12) 119.8(13) C(40)-C(35)-C(4) 124.17(19) C(13)-C(14)-C(15) 120.1(2) C(36)-C(35)-C(4) 118.25(18) C(13)-C(14)-H(24) 119.9(13) C(19)-C(18)-C(17) 121.34(19) C(15)-C(14)-H(24) 119.9(13) C(19)-C(18)-H(17) 119.0(13) C(13)-C(12)-C(11) 121.0(2) C(17)-C(18)-H(17) 119.7(13) C(13)-C(12)-H(26) 119.1(13) C(27)-C(28)-C(23) 120.9(2) C(11)-C(12)-H(26) 119.8(13) C(27)-C(28)-H(16) 120.1(13) C(29)-C(34)-C(33) 120.57(19) C(23)-C(28)-H(16) 118.9(13) C(29)-C(34)-H(11) 120.1(12) C(10)-C(5)-C(6) 120.70(19) C(33)-C(34)-H(11) 119.3(12) C(10)-C(5)-O(1) 117.00(18) O(1)-B(1)-C(11) 114.76(17) C(6)-C(5)-O(1) 122.21(19) O(1)-B(1)-C(1) 122.99(18) C(5)-C(10)-C(9) 119.7(2) C(11)-B(1)-C(1) 122.05(17) C(5)-C(10)-H(31) 118.5(14) C(8)-C(9)-C(10) 120.2(2) C(9)-C(10)-H(31) 121.7(15) C(8)-C(9)-H(30) 120.1(14) C(24)-C(23)-C(28) 117.71(18) C(10)-C(9)-H(30) 119.7(14) C(24)-C(23)-C(2) 121.40(17) C(26)-C(27)-C(28) 120.4(2) C(28)-C(23)-C(2) 120.84(17) C(26)-C(27)-H(15) 119.6(15) C(32)-C(33)-C(34) 120.2(2) C(28)-C(27)-H(15) 119.9(15) C(32)-C(33)-H(10) 119.9(13) C(37)-C(36)-C(35) 121.2(2) C(34)-C(33)-H(10) 119.9(13) C(37)-C(36)-H(36) 119.4 C(21)-C(22)-C(17) 120.5(2) C(35)-C(36)-H(36) 119.4 205 C(39)-C(40)-C(35) 121.2(2) C(7)-C(8)-C(9) 119.5(2) C(39)-C(40)-H(6) 118.1(13) C(7)-C(8)-H(29) 120.0(14) C(35)-C(40)-H(6) 120.6(13) C(9)-C(8)-H(29) 120.4(14) C(15)-C(16)-C(11) 121.2(2) C(33)-C(32)-C(31) 120.1(2) C(15)-C(16)-H(22) 117.9(14) C(33)-C(32)-H(9) 120.5(15) C(11)-C(16)-H(22) 120.9(14) C(31)-C(32)-H(9) 119.4(15) C(32)-C(31)-C(30) 119.9(2) C(26)-C(25)-C(24) 120.2(2) C(32)-C(31)-H(8) 122.0(15) C(26)-C(25)-H(13) 121.1(14) C(30)-C(31)-H(8) 118.1(15) C(24)-C(25)-H(13) 118.8(15) C(38)-C(37)-C(36) 120.2(2) C(25)-C(26)-C(27) 119.7(2) C(38)-C(37)-H(3) 119.4(15) C(25)-C(26)-H(14) 120.0(15) C(36)-C(37)-H(3) 120.4(15) C(27)-C(26)-H(14) 120.3(15) C(14)-C(13)-C(12) 120.0(2) C(14)-C(15)-C(16) 120.0(2) C(14)-C(13)-H(25) 121.5(14) C(14)-C(15)-H(23) 120.2(13) C(12)-C(13)-H(25) 118.4(15) C(16)-C(15)-H(23) 119.8(13) C(20)-C(21)-C(22) 120.9(2) C(40)-C(39)-C(38) 120.3(2) C(20)-C(21)-H(20) 120.2(14) C(40)-C(39)-H(5) 121.4(16) C(22)-C(21)-H(20) 118.9(14) C(38)-C(39)-H(5) 118.2(16) C(8)-C(7)-C(6) 121.1(2) C(37)-C(38)-C(39) 119.5(2) C(8)-C(7)-H(28) 119.8(13) C(37)-C(38)-H(4) 120.2 C(6)-C(7)-H(28) 119.2(13) C(39)-C(38)-H(4) 120.2 ______Symmetry transformations used to generate equivalent atoms:

Table A40. Crystal data and structure refinement for 3-4.

Crystallographer Adrian Houghton Empirical formula C26 H B Cl F19 Formula weight 720.53 Temperature 173(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group P 21/c Unit cell dimensions a = 11.2301(3) Å a= 90°. b = 17.6492(4) Å b= 126.554(2)°. c = 15.5641(5) Å g = 90°. Volume 2478.04(12) Å3 Z 4 Density (calculated) 1.931 Mg/m3 Absorption coefficient 0.317 mm-1 F(000) 1400 Crystal size 0.10 x 0.08 x 0.06 mm3 Theta range for data collection 2.00 to 27.57°. Index ranges -14<=h<=14, -22<=k<=22, -20<=l<=20 Reflections collected 21099 Independent reflections 5731 [R(int) = 0.0653] Completeness to theta = 27.57° 99.7 % Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9812 and 0.9690 Refinement method Full-matrix least-squares on F2 Data / restraints / parameters 5731 / 0 / 424

206 Goodness-of-fit on F2 1.176 Final R indices [I>2sigma(I)] R1 = 0.0790, wR2 = 0.1048 R indices (all data) R1 = 0.1271, wR2 = 0.1187 Largest diff. peak and hole 0.243 and -0.357 e.Å-3

Table A41. Atomic coordinates ( x 104) and equivalent isotropic displacement parameters (Å2x 103) for 3-4. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. ______x y z U(eq) ______C(1) 7527(4) 1528(2) 5727(3) 46(1) C(2) 8998(4) 1459(2) 6069(3) 42(1) C(3) 10246(4) 1717(2) 7155(3) 41(1) C(4) 10148(4) 2365(2) 7548(3) 43(1) C(5) 9243(4) 1160(2) 5371(3) 52(1) C(6) 8121(5) 925(2) 4367(3) 60(1) C(7) 6686(5) 990(2) 4032(3) 62(1) C(8) 6415(4) 1295(2) 4699(3) 57(1) C(9) 11602(4) 1247(2) 7750(3) 44(1) C(10) 11547(5) 487(2) 7904(3) 57(1) C(11) 12756(7) 26(3) 8381(3) 77(2) C(12) 14076(6) 325(4) 8704(3) 89(2) C(13) 14204(5) 1082(4) 8598(3) 77(2) C(14) 12975(4) 1534(3) 8118(3) 56(1) C(15) 11211(4) 2642(2) 8643(3) 42(1) C(16) 11793(4) 2209(2) 9547(3) 46(1) C(17) 12748(4) 2495(2) 10558(3) 51(1) C(18) 13141(4) 3243(3) 10681(3) 57(1) C(19) 12583(5) 3694(2) 9813(4) 57(1) C(20) 11639(4) 3394(2) 8812(3) 51(1) C(21) 7573(4) 1420(2) 7506(3) 46(1) C(22) 8058(4) 1785(2) 8448(3) 55(1) C(23) 8457(5) 1413(3) 9350(3) 61(1) C(25) 7871(4) 251(2) 8421(3) 56(1) C(26) 7493(4) 641(2) 7533(3) 49(1) C(24) 8357(4) 641(3) 9332(3) 60(1) Cl(1) 6094(1) 2662(1) 6083(1) 71(1) F(10) 11399(2) 1479(1) 9459(2) 58(1) F(1) 10635(2) 1111(1) 5655(2) 67(1) F(9) 13118(2) 2267(2) 7984(2) 70(1) F(14) 11119(3) 3838(1) 7963(2) 74(1) F(34) 6990(3) 240(1) 6649(2) 65(1) F(11) 13306(3) 2052(2) 11410(2) 75(1) F(12) 14087(3) 3529(2) 11663(2) 81(1) F(5) 10254(3) 183(1) 7585(2) 72(1) F(4) 4999(2) 1330(2) 4357(2) 79(1) F(17) 8949(3) 1791(2) 10240(2) 95(1) F(19) 7773(3) -501(1) 8409(2) 79(1) F(13) 12978(3) 4421(1) 9948(2) 86(1) F(16) 8199(3) 2541(1) 8503(2) 80(1) F(8) 15505(3) 1383(2) 8927(2) 114(1) F(2) 8422(3) 644(2) 3723(2) 85(1) F(6) 12660(4) -706(2) 8526(2) 115(1) F(18) 8738(3) 267(2) 10204(2) 86(1)

207 F(3) 5592(3) 741(2) 3057(2) 91(1) F(7) 15282(3) -111(2) 9157(2) 132(2) B(1) 7144(4) 1832(2) 6476(4) 49(1)

Table A42. Bond lengths [Å] and angles [°] for 3-4. ______C(1)-C(8) 1.381(5) C(14)-F(9) 1.335(5) C(1)-C(2) 1.406(5) C(15)-C(16) 1.376(5) C(1)-B(1) 1.559(6) C(15)-C(20) 1.384(5) C(2)-C(5) 1.375(5) C(16)-F(10) 1.341(4) C(2)-C(3) 1.486(5) C(16)-C(17) 1.368(5) C(3)-C(4) 1.332(5) C(17)-F(11) 1.331(4) C(3)-C(9) 1.478(5) C(17)-C(18) 1.370(6) C(4)-C(15) 1.465(5) C(18)-F(12) 1.336(4) C(4)-H(4) 0.9500 C(18)-C(19) 1.357(6) C(5)-F(1) 1.351(4) C(19)-F(13) 1.333(4) C(5)-C(6) 1.363(5) C(19)-C(20) 1.365(5) C(6)-F(2) 1.329(4) C(20)-F(14) 1.334(4) C(6)-C(7) 1.371(6) C(21)-C(26) 1.381(5) C(7)-F(3) 1.336(4) C(21)-C(22) 1.383(5) C(7)-C(8) 1.356(6) C(21)-B(1) 1.552(6) C(8)-F(4) 1.345(4) C(22)-F(16) 1.341(4) C(9)-C(10) 1.371(5) C(22)-C(23) 1.361(6) C(9)-C(14) 1.382(5) C(23)-F(17) 1.326(4) C(10)-F(5) 1.335(5) C(23)-C(24) 1.366(6) C(10)-C(11) 1.363(6) C(25)-F(19) 1.330(4) C(11)-F(6) 1.327(6) C(25)-C(24) 1.364(6) C(11)-C(12) 1.357(8) C(25)-C(26) 1.366(5) C(12)-F(7) 1.337(5) C(26)-F(34) 1.337(4) C(12)-C(13) 1.363(8) C(24)-F(18) 1.330(4) C(13)-F(8) 1.338(5) Cl(1)-B(1) 1.747(4) C(13)-C(14) 1.368(6)

C(8)-C(1)-C(2) 117.5(4) F(4)-C(8)-C(1) 119.0(4) C(8)-C(1)-B(1) 120.4(3) C(7)-C(8)-C(1) 123.0(4) C(2)-C(1)-B(1) 122.1(3) C(10)-C(9)-C(14) 116.2(4) C(5)-C(2)-C(1) 118.5(3) C(10)-C(9)-C(3) 121.4(3) C(5)-C(2)-C(3) 121.3(3) C(14)-C(9)-C(3) 122.3(4) C(1)-C(2)-C(3) 120.2(3) F(5)-C(10)-C(11) 118.3(4) C(4)-C(3)-C(9) 122.0(3) F(5)-C(10)-C(9) 118.7(4) C(4)-C(3)-C(2) 120.4(3) C(11)-C(10)-C(9) 123.0(5) C(9)-C(3)-C(2) 117.5(3) F(6)-C(11)-C(12) 119.9(5) C(3)-C(4)-C(15) 126.0(3) F(6)-C(11)-C(10) 121.2(6) C(3)-C(4)-H(4) 117.0 C(12)-C(11)-C(10) 118.9(5) C(15)-C(4)-H(4) 117.0 F(7)-C(12)-C(11) 120.7(7) F(1)-C(5)-C(6) 117.1(4) F(7)-C(12)-C(13) 118.8(6) F(1)-C(5)-C(2) 120.3(3) C(11)-C(12)-C(13) 120.5(5) C(6)-C(5)-C(2) 122.6(4) F(8)-C(13)-C(12) 120.9(5) F(2)-C(6)-C(5) 120.1(4) F(8)-C(13)-C(14) 119.6(6) F(2)-C(6)-C(7) 120.9(4) C(12)-C(13)-C(14) 119.5(5) C(5)-C(6)-C(7) 119.1(4) F(9)-C(14)-C(13) 118.3(4) F(3)-C(7)-C(8) 121.8(4) F(9)-C(14)-C(9) 119.9(4) F(3)-C(7)-C(6) 118.8(4) C(13)-C(14)-C(9) 121.8(5) C(8)-C(7)-C(6) 119.4(4) C(16)-C(15)-C(20) 116.1(3) F(4)-C(8)-C(7) 117.9(4) C(16)-C(15)-C(4) 124.5(3)

208 C(20)-C(15)-C(4) 119.4(3) F(16)-C(22)-C(23) 117.5(4) F(10)-C(16)-C(17) 117.2(3) F(16)-C(22)-C(21) 119.2(4) F(10)-C(16)-C(15) 120.1(3) C(23)-C(22)-C(21) 123.3(4) C(17)-C(16)-C(15) 122.7(4) F(17)-C(23)-C(22) 120.7(4) F(11)-C(17)-C(16) 120.7(4) F(17)-C(23)-C(24) 120.1(4) F(11)-C(17)-C(18) 120.4(4) C(22)-C(23)-C(24) 119.2(4) C(16)-C(17)-C(18) 118.9(4) F(19)-C(25)-C(24) 119.8(4) F(12)-C(18)-C(19) 119.9(4) F(19)-C(25)-C(26) 121.0(4) F(12)-C(18)-C(17) 119.7(4) C(24)-C(25)-C(26) 119.2(4) C(19)-C(18)-C(17) 120.4(4) F(34)-C(26)-C(25) 117.4(4) F(13)-C(19)-C(18) 119.6(4) F(34)-C(26)-C(21) 119.4(3) F(13)-C(19)-C(20) 120.8(4) C(25)-C(26)-C(21) 123.1(4) C(18)-C(19)-C(20) 119.6(4) F(18)-C(24)-C(25) 119.8(4) F(14)-C(20)-C(19) 119.2(4) F(18)-C(24)-C(23) 120.1(4) F(14)-C(20)-C(15) 118.6(3) C(25)-C(24)-C(23) 120.1(4) C(19)-C(20)-C(15) 122.2(4) C(21)-B(1)-C(1) 123.9(3) C(26)-C(21)-C(22) 115.0(4) C(21)-B(1)-Cl(1) 119.0(3) C(26)-C(21)-B(1) 120.8(3) C(1)-B(1)-Cl(1) 117.1(3) C(22)-C(21)-B(1) 124.2(3) ______Symmetry transformations used to generate equivalent atoms:

Table A43: Crystal data and structure refinement for 3-6 Crystallographer Denis Spasyuk Chemical formula C32 H10 B F19 Molecular weight 766.21 Temperature 173(2) Wavelength 1.54178 Crystal system ; space group Monoclinic ; P2(1)/n a = 14.5087(8) Å ; α = 90.00 ° Unit cell dimentions b = 11.4420(6) Å ; β = 97.574(5) ° c = 17.6386(10) Å ; γ = 90.00 ° Volume 2902.6(3) Å³ Z, Calculated density 4, 1.753 g/cm³ Absorption coefficient 1.707 1/mm F(000) 1512 Theta range for data collection 3.71° to 68.74° Limiting indices -16 <= h <= 17 ; -13 <= k <= 13 ; -21 <= l <= 21 Reflexion collected / unique 19959 / 5313 [R(int) = 0.0274] Completness to theta max 98.9 % Refinement method Full-matrix least-square on F² Data / restraints / parameters 5313 / 152 / 563 Goodness of fit on F² 1.030 Final R indices [I>2sigma(I)] R1 = 0.0385 ; wR2 = 0.1047 Final R indices [all data] R1 = 0.0515 ; wR2 = 0.1144 Absolute structure parameter Largest diff peak and hole 0.209 and -0.208 e/Å³

209 Table A44: Atomic coordinates (x 104) and equivalent isotropic displacements parameters (Å2 x 103) for 3- 6. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. Label x y z U(eq) B1 10078.7(1.4) 6127(2) 7478.4(1.3) 44.1(5) C1 10144.7(1.3) 7076.0(1.6) 8132.7(1.1) 42.4(4) C10 9089.4(1.4) 3598.3(1.7) 8534.1(1.2) 48.5(4) C11 9388.1(1.7) 2621.7(1.8) 8169.2(1.3) 55.7(5) C12 9927.2(1.8) 2750.3(1.9) 7594.9(1.3) 61.1(6) C13 10146.3(1.5) 3867.4(1.9) 7372.2(1.2) 53.1(5) C14 9863.2(1.3) 4861.1(1.6) 7720.9(1.1) 44.3(4) C15 8887.7(1.2) 7880.9(1.6) 8919.4(1.0) 40.4(4) C16 9250.1(1.4) 8416.8(1.8) 9595.8(1.1) 48.8(5) C17 8817.6(1.6) 9344(2) 9898.8(1.3) 57.7(5) C18 8005.5(1.6) 9786.6(1.9) 9515.0(1.4) 57.9(5) C19 7626.1(1.4) 9274.0(1.8) 8845.6(1.3) 50.9(5) C2 11061.8(1.4) 6789(2) 8683.2(1.2) 55.5(5) C20 8061.9(1.3) 8342.2(1.7) 8556.3(1.1) 43.2(4) C21 8168.8(1.3) 5662.2(1.6) 9132.1(1.1) 42.5(4) C22 7285.7(1.4) 5394.3(1.7) 8781.1(1.1) 47.0(4) C23 6539.7(1.4) 5282.0(1.8) 9182.3(1.4) 54.0(5) C24 6665.5(1.5) 5450(2) 9961.7(1.4) 57.3(5) C25 7529.5(1.6) 5720(2) 10331.3(1.2) 56.2(5) C26 8268.5(1.4) 5806.3(1.8) 9918.9(1.2) 49.6(4) C28A 10101.9(1.6) 6453.2(1.8) 6608.8(1.2) 52.2(5) C29A 10944(18) 6245(17) 6225(13) 63(4) C29B 10742(15) 6423(17) 6162(14) 64(4) C3 11934.3(1.6) 7073(3) 8314.6(1.6) 74.3(7) C30A 10951(14) 6593(14) 5505(10) 69(3) C30B 10634(13) 6796(12) 5377(9) 67(3) C31A 10179(15) 7111(13) 5104(10) 64(3) C31B 9798(16) 7275(12) 5069(9) 65(3) C32A 9392(13) 7266(14) 5414(10) 59(3) C32B 9093(13) 7353(11) 5516(8) 53(3) C33A 9410(18) 6940(20) 6154(15) 53(4) C33B 9237(16) 6968(18) 6271(12) 41(3) C4 11943(2) 8357(3) 8080.9(1.8) 86.5(9) C5 11077.3(1.8) 8686(2) 7546.4(1.5) 66.9(6) C6 10185.1(1.6) 8367.5(1.7) 7874.8(1.2) 51.5(5) C7 9330.1(1.2) 6851.1(1.6) 8586.3(1.0) 39.4(4) C8 8971.5(1.2) 5786.5(1.6) 8683(1) 40.0(4) C9 9315.3(1.2) 4721.2(1.6) 8324.5(1.0) 41.5(4) F1 8577.9(1.0) 3387.5(1.1) 9098.4(8) 64.3(3) F10 7658.5(8) 7854.5(1.1) 7907.6(7) 56.1(3) F11 6816.7(1.0) 9667.1(1.3) 8485.6(9) 73.9(4) F12 7581.7(1.1) 10680.1(1.4) 9807.2(1.0) 85.7(5) F13 9183.8(1.1) 9809.5(1.5) 10566.0(9) 83.5(5) F14 10052.0(9) 8035.7(1.2) 9986.0(8) 66.5(4) F15 9109.5(9) 6036.9(1.4) 10300.9(7) 67.0(4) F16 7653.4(1.2) 5886.5(1.6) 11087.7(8) 80.6(4) F17 5946.3(1.0) 5340.6(1.5) 10358.7(1.0) 79.3(4) F18 5702.5(9) 4991.8(1.4) 8824.8(9) 74.0(4) F19 7145.3(9) 5213.9(1.2) 8022.7(7) 61.3(3) F2 9150.2(1.2) 1555.7(1.1) 8383.5(9) 76.7(4) F3 10233.4(1.4) 1810.0(1.3) 7249.1(1.0) 88.9(5) F4 10667.5(1.1) 3955.6(1.2) 6799.0(9) 73.9(4)

210 F5A 11686(12) 5842(13) 6519(7) 75(5) F5B 11611(14) 5940(16) 6513(8) 128(7) F6A 11542(15) 6576(13) 5071(9) 188(8) F6B 11493(15) 6666(12) 5056(8) 130(7) F7A 10090(30) 7504(18) 4377(12) 139(7) F7B 9730(30) 7688(16) 4349(17) 130(7) F8A 8526(18) 7775(10) 5089(11) 116(4) F8B 8328(16) 7816(10) 5196(10) 93(4) F9A 8624(15) 7117(13) 6564(12) 71(4) F9B 8543(9) 7108(9) 6621(8) 60(2)

Table A45: Bond lengths (Å) and angles (˚) for 3-6. Bond Length (Å) C25 - F16 1.336(3) B1 - C1 1.578(3) C26 - F15 1.340(2) B1 - C14 1.554(3) C28A - C29A 1.49(2) B1 - C28A 1.583(3) C28A - C29B 1.30(2) C1 - C2 1.575(3) C28A - C33A 1.32(3) C1 - C6 1.550(3) C28A - C33B 1.44(3) C1 - C7 1.534(3) C29A - C30A 1.33(3) C10 - C11 1.387(3) C29A - F5A 1.22(4) C10 - F1 1.339(2) C29B - C30B 1.44(3) C11 - C12 1.367(4) C29B - F5B 1.44(3) C11 - F2 1.336(3) C3 - C4 1.527(4) C12 - C13 1.386(3) C3 - H3A 0.9900 C12 - F3 1.341(3) C3 - H3B 0.9900 C13 - C14 1.381(3) C30A - C31A 1.378(15) C13 - F4 1.344(3) C30A - F6A 1.22(2) C15 - C16 1.382(3) C30B - C31B 1.375(14) C15 - C20 1.386(3) C30B - F6B 1.44(2) C16 - C17 1.376(3) C31A - C32A 1.341(14) C16 - F14 1.344(2) C31A - F7A 1.35(3) C17 - C18 1.376(3) C31B - C32B 1.374(12) C17 - F13 1.336(3) C31B - F7B 1.35(3) C18 - C19 1.367(3) C32A - C33A 1.35(3) C18 - F12 1.331(2) C32A - F8A 1.43(3) C19 - C20 1.372(3) C32B - C33B 1.39(2) C19 - F11 1.337(2) C32B - F8B 1.29(3) C2 - C3 1.532(3) C33A - F9A 1.44(4) C2 - H2A 0.9900 C33B - F9B 1.26(2) C2 - H2B 0.9900 C4 - C5 1.515(4) C20 - F10 1.337(2) C4 - H4A 0.9900 C21 - C22 1.382(3) C4 - H4B 0.9900 C21 - C26 1.386(3) C5 - C6 1.530(3) C22 - C23 1.375(3) C5 - H5A 0.9900 C22 - F19 1.342(2) C5 - H5B 0.9900 C23 - C24 1.376(3) C6 - H6A 0.9900 C23 - F18 1.335(3) C6 - H6B 0.9900 C24 - C25 1.370(3) C7 - C15 1.498(3) C24 - F17 1.337(3) C7 - C8 1.344(3) C25 - C26 1.376(3) C8 - C21 1.499(3)

211 C8 - C9 1.489(3) C9 - C14 1.419(3) C9 - C10 1.388(3)

Atoms Angle (°) C3 - C4 - H4A 109.3 C1 - B1 - C28A 122.64(18) C3 - C4 - H4B 109.3 C1 - C2 - H2A 109.2 C30A - C29A - C28A 119.6(16) C1 - C2 - H2B 109.2 C30B - C29B - F5B 120.4(17) C1 - C6 - H6A 108.8 C30B - C31B - C32B 118.9(13) C1 - C6 - H6B 108.8 C31A - C32A - C33A 116.6(14) C10 - C9 - C14 118.65(17) C31A - C32A - F8A 129.7(19) C10 - C9 - C8 122.72(18) C31B - C30B - C29B 118.5(12) C11 - C10 - C9 121.5(2) C31B - C30B - F6B 130.5(16) C11 - C12 - C13 119.0(2) C31B - C32B - C33B 120.0(12) C12 - C11 - C10 120.1(2) C32A - C31A - C30A 121.7(15) C13 - C14 - B1 124.24(19) C32A - C31A - F7A 111(2) C13 - C14 - C9 118.05(18) C32A - C33A - F9A 122(2) C14 - B1 - C1 115.79(18) C32B - C33B - C28A 122.4(12) C14 - B1 - C28A 121.14(17) C33A - C28A - B1 125.1(10) C14 - C13 - C12 122.7(2) C33A - C28A - C29A 113.2(12) C14 - C9 - C8 118.58(16) C33A - C28A - C33B 13.6(14) C15 - C7 - C1 118.16(16) C33A - C32A - F8A 113.7(18) C16 - C15 - C20 115.92(17) C33B - C28A - B1 111.6(8) C16 - C15 - C7 123.61(16) C33B - C28A - C29A 126.7(11) C17 - C16 - C15 122.43(18) C4 - C3 - C2 110.8(2) C18 - C17 - C16 119.82(19) C4 - C3 - H3A 109.5 C18 - C19 - C20 120.11(18) C4 - C3 - H3B 109.5 C19 - C18 - C17 119.24(19) C4 - C5 - C6 112.2(2) C19 - C20 - C15 122.46(18) C4 - C5 - H5A 109.2 C2 - C1 - B1 105.81(16) C4 - C5 - H5B 109.2 C2 - C3 - H3A 109.5 C5 - C4 - C3 111.8(2) C2 - C3 - H3B 109.5 C5 - C4 - H4A 109.3 C20 - C15 - C7 120.47(16) C5 - C4 - H4B 109.3 C22 - C21 - C26 116.31(18) C5 - C6 - C1 113.89(18) C22 - C21 - C8 121.55(17) C5 - C6 - H6A 108.8 C22 - C23 - C24 119.4(2) C5 - C6 - H6B 108.8 C23 - C22 - C21 122.4(2) C6 - C1 - B1 116.25(17) C24 - C25 - C26 119.5(2) C6 - C1 - C2 108.54(17) C25 - C24 - C23 120.0(2) C6 - C5 - H5A 109.2 C25 - C26 - C21 122.3(2) C6 - C5 - H5B 109.2 C26 - C21 - C8 122.14(17) C7 - C1 - B1 106.82(15) C28A - C29B - C30B 125.6(15) C7 - C1 - C2 106.86(15) C28A - C29B - F5B 114.0(19) C7 - C1 - C6 112.01(16) C28A - C33A - C32A 128.1(15) C7 - C8 - C21 119.58(17) C28A - C33A - F9A 110.0(19) C7 - C8 - C9 122.07(17) C29A - C28A - B1 121.7(10) C8 - C7 - C1 123.78(16) C29A - C30A - C31A 120.7(14) C8 - C7 - C15 118.02(17) C29B - C28A - B1 133.7(11) C9 - C14 - B1 117.68(16) C29B - C28A - C29A 12.5(18) C9 - C8 - C21 118.28(16) C29B - C28A - C33A 101.0(13) F1 - C10 - C11 115.93(18) C29B - C28A - C33B 114.5(12) F1 - C10 - C9 122.54(18) C29B - C30B - F6B 110.8(15) F10 - C20 - C15 119.39(17) C3 - C2 - C1 111.88(19) F10 - C20 - C19 118.13(17) C3 - C2 - H2A 109.2 F11 - C19 - C18 119.61(18) C3 - C2 - H2B 109.2 F11 - C19 - C20 120.25(19)

212 F12 - C18 - C17 120.1(2) F3 - C12 - C13 120.6(2) F12 - C18 - C19 120.7(2) F4 - C13 - C12 117.07(19) F13 - C17 - C16 120.0(2) F4 - C13 - C14 120.2(2) F13 - C17 - C18 120.15(19) F5A - C29A - C28A 126.5(18) F14 - C16 - C15 120.21(17) F5A - C29A - C30A 113.7(17) F14 - C16 - C17 117.36(17) F6A - C30A - C29A 133(2) F15 - C26 - C21 119.66(19) F6A - C30A - C31A 106(2) F15 - C26 - C25 118.00(19) F7A - C31A - C30A 127(2) F16 - C25 - C24 120.1(2) F7B - C31B - C30B 118(2) F16 - C25 - C26 120.4(2) F7B - C31B - C32B 123(2) F17 - C24 - C23 120.0(2) F8B - C32B - C31B 116.0(17) F17 - C24 - C25 120.0(2) F8B - C32B - C33B 124.0(16) F18 - C23 - C22 120.6(2) F9B - C33B - C28A 124.0(17) F18 - C23 - C24 119.9(2) F9B - C33B - C32B 113.6(19) F19 - C22 - C21 119.38(18) H2A - C2 - H2B 107.9 F19 - C22 - C23 118.17(18) H3A - C3 - H3B 108.1 F2 - C11 - C10 119.7(2) H4A - C4 - H4B 107.9 F2 - C11 - C12 120.2(2) H5A - C5 - H5B 107.9 F3 - C12 - C11 120.5(2) H6A - C6 - H6B 107.7

Table A46: Crystal data and structure refinement for 4-1 Crystallographer Adrian Houghton Chemical formula C32 H16 B F19 Si Molecular weight 800.35 Temperature 173(2) Wavelength 1.54178 Crystal system ; space group Triclinic ; P-1 a = 8.8644(6) Å ; α = 84.427(4) ° Unit cell dimentions b = 10.8121(7) Å ; β = 84.854(4) ° c = 18.0451(12) Å ; γ = 70.356(4) ° Volume 1618.13(19) Å³ Z, Calculated density 2, 1.643 g/cm³ Absorption coefficient 1.899 1/mm F(000) 796 Theta range for data collection 2.46° to 66.66° Limiting indices -10 <= h <= 10 ; -12 <= k <= 12 ; -21 <= l <= 18 Reflexion collected / unique 20449 / 5579 [R(int) = 0.0186] Completness to theta max 97.4 % Refinement method Full-matrix least-square on F² Data / restraints / parameters 5579 / 0 / 485 Goodness of fit on F² 1.043 Final R indices [I>2sigma(I)] R1 = 0.0413 ; wR2 = 0.1152 Final R indices [all data] R1 = 0.0463 ; wR2 = 0.1204 Absolute structure parameter Largest diff peak and hole 0.589 and -0.209 e/Å³

Table A47: Atomic coordinates (x 104) and equivalent isotropic displacements parameters (Å2 x 103) for 4-1. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor. Label x y z U(eq) B1 665(3) 8361(2) 2045.2(1.2) 35.4(4) C1 1355(2) 7431.8(1.8) 2779.4(1.0) 34.5(4) C10 1684(3) 10238(2) 1377.1(1.3) 47.6(5) C11 1599(3) 11537(3) 1219.0(1.4) 57.0(6)

213 C12 482(3) 12506(2) 1595.6(1.4) 57.0(6) C13 -526(3) 12176(2) 2141.5(1.5) 55.3(6) C14 -408(3) 10872(2) 2285.1(1.2) 45.8(5) C15 1122(2) 7728.6(1.8) 3572.2(1.1) 36.7(4) C16 1668(2) 8660.8(1.9) 3832.6(1.1) 39.3(4) C17 1598(3) 8858(2) 4578.7(1.2) 48.1(5) C18 951(3) 8132(2) 5093.9(1.2) 55.3(6) C19 360(3) 7212(2) 4860.5(1.3) 55.1(6) C2 2234(2) 6216.7(1.8) 2575.1(1.0) 34.4(4) C20 447(3) 7026.3(1.9) 4109.6(1.2) 44.1(5) C21 3075(2) 5093.8(1.8) 3094.8(1.0) 37.2(4) C22 4262(3) 5139(2) 3529.4(1.2) 46.6(5) C23 5012(3) 4102(3) 4022.6(1.5) 63.8(7) C24 4578(3) 2986(3) 4089.9(1.5) 68.5(7) C25 3420(3) 2899(2) 3663.5(1.5) 58.6(6) C26 2675(3) 3950(2) 3178.2(1.2) 44.5(5) C27 -4036(3) 9246(3) 2737.3(1.7) 70.2(7) C28 -3612(4) 8738(4) 3535.7(1.8) 82.6(9) C29 -3140(3) 9377(3) 1053.5(1.7) 76.8(8) C3 2290(2) 6121.1(1.8) 1762.6(1.0) 34.4(4) C30 -3380(5) 10795(4) 999(2) 95.0(1.1) C31 -2240(3) 6669(3) 1942(2) 84.9(1.0) C32 -3667(4) 6364(3) 1695(2) 80.5(9) C4 3129(2) 5076.0(1.9) 1343.2(1.1) 40.1(4) C5 3058(3) 5203(2) 576.2(1.2) 43.8(5) C6 2163(3) 6373(2) 228.8(1.1) 44.6(5) C7 1333(2) 7431(2) 651.4(1.1) 40.4(4) C8 1376(2) 7334.4(1.8) 1410.7(1.1) 35.7(4) C9 658(2) 9851.2(1.8) 1904.3(1.1) 38.9(4) F1 4052.4(1.7) 3918.2(1.2) 1652.1(7) 54.8(3) F10 4712.4(1.6) 6209.5(1.4) 3482.0(9) 61.6(4) F11 6150(2) 4189(2) 4435.4(1.1) 95.6(6) F12 5281(3) 1985(2) 4571.2(1.3) 110.6(8) F13 3000(2) 1812.9(1.4) 3722.6(1.1) 85.5(5) F14 1514.9(1.8) 3861.5(1.3) 2787.5(8) 59.6(4) F15 2348.7(1.5) 9367.8(1.2) 3351.4(7) 49.5(3) F16 2167.5(1.8) 9760.7(1.3) 4799.5(8) 63.6(4) F17 874(2) 8315.6(1.6) 5818.4(8) 80.7(5) F18 -281(2) 6501.9(1.6) 5354.5(9) 82.8(5) F19 -141.3(1.7) 6128.2(1.3) 3900.3(8) 57.9(3) F2 3876.9(1.8) 4185.5(1.3) 170.6(7) 59.6(4) F3 2127.7(1.9) 6490.4(1.5) -516.6(7) 62.8(4) F4 500.2(1.6) 8563.1(1.3) 278.9(7) 53.4(3) F5 2832.5(1.7) 9338.7(1.5) 990.0(9) 67.9(4) F6 2600(2) 11849.4(1.8) 686.8(1.0) 87.8(6) F7 366(2) 13766.8(1.4) 1425(1) 80.8(5) F8 -1625(2) 13111.1(1.4) 2520.8(1.1) 84.2(5) F9 -1424.6(1.9) 10592.7(1.4) 2822.0(8) 65.1(4) Si1 -2642.5(7) 8449.0(6) 1981.4(4) 48.5(17)

Table A48: Bond lengths (Å) and angles (˚) for 4-1. Bond Length (Å) C1 - C15 1.478(3) B1 - C9 1.605(3) C11 - C10 1.383(3) B1 - H1 1.46(2) C11 - C12 1.364(4) C1 - B1 1.616(3) C12 - C13 1.373(4) 214 C14 - C13 1.379(3) C32 - H32B 0.9800 C14 - C9 1.383(3) C32 - H32C 0.9800 C16 - C15 1.390(3) C4 - C3 1.380(3) C16 - C17 1.376(3) C4 - C5 1.383(3) C18 - C17 1.370(4) C5 - C6 1.372(3) C18 - C19 1.382(4) C7 - C6 1.391(3) C2 - C1 1.350(3) C8 - B1 1.608(3) C2 - C3 1.475(3) C8 - C3 1.413(3) C20 - C15 1.390(3) C8 - C7 1.367(3) C20 - C19 1.380(3) C9 - C10 1.390(3) C21 - C2 1.485(3) F1 - C4 1.344(2) C21 - C22 1.384(3) F10 - C22 1.338(3) C21 - C26 1.388(3) F11 - C23 1.339(3) C22 - C23 1.380(3) F12 - C24 1.332(3) C24 - C23 1.376(4) F13 - C25 1.338(3) C25 - C24 1.369(4) F14 - C26 1.332(3) C26 - C25 1.378(3) F15 - C16 1.338(2) C27 - C28 1.524(4) F16 - C17 1.345(3) C27 - H27A 0.9900 F17 - C18 1.334(3) C27 - H27B 0.9900 F18 - C19 1.333(3) C28 - H28A 0.9800 F19 - C20 1.344(3) C28 - H28B 0.9800 F2 - C5 1.340(2) C28 - H28C 0.9800 F3 - C6 1.341(2) C29 - C30 1.470(5) F4 - C7 1.348(2) C29 - H29A 0.9900 F5 - C10 1.345(3) C29 - H29B 0.9900 F6 - C11 1.345(3) C30 - H30A 0.9800 F7 - C12 1.339(2) C30 - H30B 0.9800 F8 - C13 1.339(3) C30 - H30C 0.9800 F9 - C14 1.346(3) C31 - C32 1.522(4) Si1 - C27 1.828(3) C31 - H31A 0.9900 Si1 - C29 1.874(3) C31 - H31B 0.9900 Si1 - C31 1.843(3) C32 - H32A 0.9800 Si1 - H1 1.51(2)

Atoms Angle (°) C20 - C19 - C18 119.5(2) C1 - B1 - H1 101.5(9) C22 - C21 - C2 122.23(18) C1 - C2 - C21 124.92(18) C22 - C21 - C26 116.71(18) C1 - C2 - C3 112.20(16) C23 - C22 - C21 121.8(2) C10 - C9 - B1 123.26(19) C24 - C23 - C22 119.7(2) C11 - C10 - C9 123.1(2) C24 - C25 - C26 119.3(2) C11 - C12 - C13 119.4(2) C25 - C24 - C23 120.2(2) C12 - C11 - C10 120.0(2) C25 - C26 - C21 122.3(2) C12 - C13 - C14 119.1(2) C26 - C21 - C2 121.05(18) C13 - C14 - C9 124.2(2) C27 - C28 - H28A 109.5 C14 - C9 - B1 122.63(18) C27 - C28 - H28B 109.5 C14 - C9 - C10 114.09(18) C27 - C28 - H28C 109.5 C15 - C1 - B1 130.11(16) C27 - Si1 - C29 112.20(14) C16 - C15 - C1 121.93(17) C27 - Si1 - C31 116.50(16) C16 - C15 - C20 116.03(19) C27 - Si1 - H1 104.4(9) C17 - C16 - C15 122.5(2) C28 - C27 - H27A 107.9 C17 - C18 - C19 119.8(2) C28 - C27 - H27B 107.9 C18 - C17 - C16 119.8(2) C28 - C27 - Si1 117.8(2) C19 - C20 - C15 122.3(2) C29 - C30 - H30A 109.5 C2 - C1 - B1 109.09(16) C29 - C30 - H30B 109.5 C2 - C1 - C15 120.79(17) C29 - C30 - H30C 109.5 C20 - C15 - C1 121.89(18) C29 - Si1 - H1 106.4(9) 215 C3 - C2 - C21 122.87(16) F16 - C17 - C18 120.3(2) C3 - C4 - C5 120.14(18) F17 - C18 - C17 120.4(2) C3 - C8 - B1 107.65(16) F17 - C18 - C19 119.9(2) C30 - C29 - H29A 107.9 F18 - C19 - C18 120.5(2) C30 - C29 - H29B 107.9 F18 - C19 - C20 120.0(2) C30 - C29 - Si1 117.5(2) F19 - C20 - C15 119.60(19) C31 - C32 - H32A 109.5 F19 - C20 - C19 118.05(19) C31 - C32 - H32B 109.5 F2 - C5 - C4 119.95(19) C31 - C32 - H32C 109.5 F2 - C5 - C6 119.95(19) C31 - Si1 - C29 112.27(17) F3 - C6 - C5 119.5(2) C31 - Si1 - H1 103.9(9) F3 - C6 - C7 120.77(19) C32 - C31 - H31A 109.1 F4 - C7 - C6 117.10(18) C32 - C31 - H31B 109.1 F4 - C7 - C8 121.36(18) C32 - C31 - Si1 112.5(2) F5 - C10 - C11 116.4(2) C4 - C3 - C2 129.21(17) F5 - C10 - C9 120.42(19) C4 - C3 - C8 120.27(18) F6 - C11 - C10 120.2(3) C5 - C6 - C7 119.71(18) F6 - C11 - C12 119.8(2) C6 - C5 - C4 120.10(19) F7 - C12 - C11 119.9(2) C7 - C8 - B1 134.02(17) F7 - C12 - C13 120.7(3) C7 - C8 - C3 118.23(18) F8 - C13 - C12 120.4(2) C8 - B1 - C1 100.58(15) F8 - C13 - C14 120.5(2) C8 - B1 - H1 106.5(9) F9 - C14 - C13 117.1(2) C8 - C3 - C2 110.46(16) F9 - C14 - C9 118.65(18) C8 - C7 - C6 121.54(18) H27A - C27 - H27B 107.2 C9 - B1 - C1 122.89(16) H28A - C28 - H28B 109.5 C9 - B1 - C8 120.84(17) H28A - C28 - H28C 109.5 C9 - B1 - H1 102.0(9) H28B - C28 - H28C 109.5 F1 - C4 - C3 122.28(18) H29A - C29 - H29B 107.2 F1 - C4 - C5 117.57(18) H30A - C30 - H30B 109.5 F10 - C22 - C21 120.29(19) H30A - C30 - H30C 109.5 F10 - C22 - C23 117.9(2) H30B - C30 - H30C 109.5 F11 - C23 - C22 119.9(3) H31A - C31 - H31B 107.8 F11 - C23 - C24 120.4(2) H32A - C32 - H32B 109.5 F12 - C24 - C23 120.1(3) H32A - C32 - H32C 109.5 F12 - C24 - C25 119.7(3) H32B - C32 - H32C 109.5 F13 - C25 - C24 120.5(2) Si1 - C27 - H27A 107.9 F13 - C25 - C26 120.3(3) Si1 - C27 - H27B 107.9 F14 - C26 - C21 119.40(18) Si1 - C29 - H29A 107.9 F14 - C26 - C25 118.2(2) Si1 - C29 - H29B 107.9 F15 - C16 - C15 119.69(17) Si1 - C31 - H31A 109.1 F15 - C16 - C17 117.71(19) Si1 - C31 - H31B 109.1 F16 - C17 - C16 120.0(2)

216

APPENDIX B: CALCULATED GEOMETRIES

Table A49: Atomic coordinates (Å) for 1-1 # opt B3LYP/6-311g(d) ------Center Atomic Atomic Coordinates (Angstroms) Number Number Type X Y Z ------1 6 0 1.255621 0.392829 -0.019968 2 6 0 0.770472 -0.876645 -0.011945 3 6 0 -0.763104 -0.883264 0.011949 4 6 0 -1.259066 0.382046 0.020125 5 5 0 -0.005895 1.357579 0.000392 6 6 0 -1.037768 5.026566 -0.651856 7 6 0 -1.041871 3.636020 -0.632418 8 6 0 -0.012593 2.904996 0.000269 9 6 0 1.010326 3.645098 0.632761 10 6 0 0.994224 5.035557 0.651752 11 6 0 -0.024791 5.729391 -0.000181 12 6 0 -2.692327 0.748496 -0.003785 13 6 0 -3.563948 0.252544 -0.987206 14 6 0 -4.906145 0.619398 -1.008712 15 6 0 -5.414422 1.487322 -0.043511 16 6 0 -4.563491 1.991495 0.938088 17 6 0 -3.217979 1.633669 0.951787 18 6 0 -1.550061 -2.136512 0.017876 19 6 0 -1.328732 -3.138874 -0.939582 20 6 0 -2.096426 -4.299658 -0.946642 21 6 0 -3.084167 -4.494023 0.016826 22 6 0 -3.304138 -3.514194 0.983632 23 6 0 -2.550519 -2.345027 0.980026 24 1 0 -1.831582 5.563864 -1.161341 25 1 0 -1.849057 3.105559 -1.124031 26 1 0 1.822046 3.121773 1.124563 27 1 0 1.783377 5.579828 1.161074 28 1 0 -0.029507 6.815246 -0.000377 29 1 0 -3.179739 -0.423476 -1.743314 30 1 0 -5.557603 0.224735 -1.782499 31 1 0 -6.462016 1.770997 -0.058970 32 1 0 -4.946063 2.670393 1.694161 33 1 0 -2.563068 2.039217 1.715965 34 1 0 -0.558178 -3.003100 -1.690153 35 1 0 -1.916290 -5.057185 -1.702859 36 1 0 -3.676312 -5.403687 0.016189

217 37 1 0 -4.068604 -3.657968 1.740716 38 1 0 -2.732869 -1.582961 1.729204 39 6 0 1.568295 -2.123025 -0.017993 40 6 0 1.356360 -3.126832 0.940076 41 6 0 2.134187 -4.280848 0.947149 42 6 0 3.122954 -4.467007 -0.016884 43 6 0 3.333719 -3.485730 -0.984270 44 6 0 2.569915 -2.323177 -0.980672 45 6 0 2.685746 0.771277 0.003849 46 6 0 3.203736 1.661605 -0.951121 47 6 0 4.546250 2.030533 -0.937553 48 6 0 5.401643 1.532585 0.043347 49 6 0 4.900876 0.659693 1.007994 50 6 0 3.561766 0.281738 0.986591 51 1 0 0.585093 -2.997521 1.691071 52 1 0 1.961207 -5.039577 1.703835 53 1 0 3.723020 -5.371465 -0.016239 54 1 0 4.098930 -3.623140 -1.741783 55 1 0 2.745132 -1.559826 -1.730254 56 1 0 2.545219 2.062324 -1.714741 57 1 0 4.922956 2.713172 -1.693201 58 1 0 6.446864 1.824890 0.058697 59 1 0 5.555825 0.269816 1.781259 60 1 0 3.183444 -0.398056 1.742276 ------

Table A50: Atomic coordinates (Å) for 1-2 # opt B3LYP/6-311g(d)

------Center Atomic Atomic Coordinates (Angstroms) Number Number Type X Y Z ------1 6 0 -0.854445 0.994401 -0.007387 2 6 0 0.495548 1.042612 -0.007296 3 6 0 1.098775 -0.359962 0.001073 4 6 0 0.136300 -1.308296 -0.007982 5 5 0 -1.246824 -0.538382 -0.006214 6 6 0 -4.309976 -2.752674 -0.846905 7 6 0 -3.036871 -2.203171 -0.838354 8 6 0 -2.674658 -1.150075 0.006903 9 6 0 -3.671471 -0.677419 0.865530 10 6 0 -4.948739 -1.216354 0.899585 11 6 0 -5.267543 -2.257132 0.032934 12 6 0 0.366839 -2.761564 -0.018108 13 6 0 1.121115 -3.399722 -1.005718 14 6 0 1.302705 -4.776455 -1.019971 15 6 0 0.719437 -5.557712 -0.029643

218 16 6 0 -0.041121 -4.955582 0.966581 17 6 0 -0.207700 -3.578634 0.958174 18 6 0 2.556683 -0.588647 0.023491 19 6 0 3.379649 -0.107180 -0.996292 20 6 0 4.751025 -0.316478 -0.997013 21 6 0 5.333013 -1.027352 0.046816 22 6 0 4.540989 -1.522122 1.077262 23 6 0 3.170504 -1.301669 1.056556 24 9 0 -4.625943 -3.742082 -1.683955 25 9 0 -2.144370 -2.689338 -1.716174 26 9 0 -3.391381 0.311054 1.730484 27 9 0 -5.867446 -0.753776 1.748984 28 9 0 -6.490191 -2.778459 0.044391 29 9 0 1.677099 -2.683561 -1.994635 30 9 0 2.025748 -5.353904 -1.983032 31 9 0 0.889999 -6.879330 -0.033495 32 9 0 -0.596125 -5.701963 1.924710 33 9 0 -0.935766 -3.021325 1.939630 34 9 0 2.835578 0.553734 -2.028034 35 9 0 5.508796 0.146868 -1.992734 36 9 0 6.647294 -1.236451 0.058348 37 9 0 5.103100 -2.196769 2.081744 38 9 0 2.440344 -1.775941 2.072169 39 6 0 1.330025 2.260009 -0.018584 40 6 0 2.233871 2.526285 1.011873 41 6 0 3.021964 3.667918 1.024239 42 6 0 2.915106 4.581840 -0.018316 43 6 0 2.023301 4.347319 -1.059163 44 6 0 1.244030 3.198482 -1.050261 45 6 0 -1.754401 2.158873 -0.007423 46 6 0 -2.732640 2.297224 -0.994562 47 6 0 -3.622598 3.361042 -1.013885 48 6 0 -3.550678 4.329527 -0.018809 49 6 0 -2.591637 4.222565 0.981383 50 6 0 -1.712430 3.147519 0.978497 51 9 0 2.330693 1.674764 2.042841 52 9 0 3.868116 3.899163 2.029670 53 9 0 3.664862 5.681400 -0.019085 54 9 0 1.928768 5.221447 -2.062707 55 9 0 0.411354 2.994326 -2.077043 56 9 0 -2.815174 1.382430 -1.974544 57 9 0 -4.537285 3.465894 -1.981079 58 9 0 -4.397836 5.358149 -0.025340 59 9 0 -2.527667 5.147212 1.942921 60 9 0 -0.819202 3.063949 1.975936 ------

Table A51: Atomic coordinates (Å) for 1-3 # opt B3LYP/6-311g(d)

------Center Atomic Atomic Coordinates (Angstroms) Number Number Type X Y Z ------

219 1 6 0 1.444762 3.210810 0.040642 2 6 0 0.811574 4.468337 0.017745 3 6 0 -0.569418 4.564122 -0.039594 4 6 0 -1.354452 3.395743 -0.058149 5 6 0 -0.750005 2.148953 -0.018455 6 6 0 0.663994 2.068790 0.005151 7 6 0 1.099495 0.634096 0.014706 8 6 0 0.026664 -0.216337 0.003173 9 5 0 -1.284829 0.667538 -0.014030 10 6 0 -4.500998 -1.336316 -0.803119 11 6 0 -3.164623 -0.954895 -0.737027 12 6 0 -2.764640 0.206163 -0.043594 13 6 0 -3.773742 0.950541 0.602841 14 6 0 -5.106299 0.552756 0.570717 15 6 0 -5.474171 -0.587692 -0.142494 16 6 0 0.114100 -1.694109 -0.009179 17 6 0 0.899554 -2.380150 -0.949805 18 6 0 0.957304 -3.770600 -0.959905 19 6 0 0.235493 -4.511819 -0.025773 20 6 0 -0.551513 -3.847842 0.913141 21 6 0 -0.617961 -2.457255 0.915151 22 6 0 2.532725 0.267509 0.068126 23 6 0 3.438147 0.771394 -0.878884 24 6 0 4.785252 0.422166 -0.833553 25 6 0 5.256935 -0.420334 0.170893 26 6 0 4.369898 -0.919140 1.123559 27 6 0 3.020687 -0.584832 1.069386 28 1 0 2.526612 3.152768 0.089108 29 1 0 1.416337 5.369734 0.041008 30 1 0 -1.046099 5.538851 -0.067723 31 1 0 -2.435405 3.484987 -0.110715 32 1 0 -4.783655 -2.225159 -1.358612 33 1 0 -2.418265 -1.559549 -1.239848 34 1 0 -3.504184 1.841685 1.160409 35 1 0 -5.860092 1.134757 1.092029 36 1 0 -6.515367 -0.893093 -0.181200 37 1 0 1.463755 -1.814635 -1.683362 38 1 0 1.569004 -4.276680 -1.700530 39 1 0 0.282729 -5.596197 -0.032365 40 1 0 -1.120580 -4.413645 1.644469 41 1 0 -1.240473 -1.951189 1.645479 42 1 0 3.078105 1.420844 -1.669942 43 1 0 5.466892 0.810533 -1.583812 44 1 0 6.308243 -0.686872 0.211099 45 1 0 4.729022 -1.574617 1.910613 46 1 0 2.334984 -0.980580 1.809855 ------

Table A52: Atomic coordinates (Å) for 1-4 # opt B3LYP/6-311g(d)

------Center Atomic Atomic Coordinates (Angstroms) Number Number Type X Y Z

220 ------1 6 0 1.432126 3.338494 0.058737 2 6 0 0.796307 4.596390 0.007323 3 6 0 -0.576811 4.683801 -0.082233 4 6 0 -1.342427 3.503089 -0.115639 5 6 0 -0.740323 2.269852 -0.049330 6 6 0 0.677738 2.191096 0.010728 7 6 0 1.105294 0.761993 0.042456 8 6 0 0.032101 -0.075804 -0.002923 9 5 0 -1.271260 0.799557 -0.060868 10 6 0 -4.459008 -1.113983 -1.147896 11 6 0 -3.148986 -0.666938 -1.058336 12 6 0 -2.745379 0.306679 -0.141964 13 6 0 -3.736158 0.807166 0.706696 14 6 0 -5.052076 0.371539 0.656744 15 6 0 -5.412754 -0.591786 -0.280115 16 6 0 0.113899 -1.547573 0.007030 17 6 0 0.809246 -2.269437 -0.965448 18 6 0 0.843997 -3.657595 -0.968418 19 6 0 0.168406 -4.364164 0.019474 20 6 0 -0.536574 -3.677051 1.001273 21 6 0 -0.556330 -2.289863 0.981729 22 6 0 2.519798 0.343140 0.141488 23 6 0 3.442852 0.672466 -0.852623 24 6 0 4.769275 0.275856 -0.783001 25 6 0 5.202664 -0.471775 0.307204 26 6 0 4.308597 -0.815740 1.314026 27 6 0 2.983095 -0.411212 1.221086 28 9 0 2.769186 3.336501 0.147855 29 9 0 1.535456 5.702343 0.043892 30 9 0 -1.172750 5.874853 -0.137241 31 9 0 -2.667876 3.643984 -0.209631 32 9 0 -4.812507 -2.030380 -2.052123 33 9 0 -2.255751 -1.177165 -1.924545 34 9 0 -3.414777 1.714351 1.639798 35 9 0 -5.969285 0.857572 1.495326 36 9 0 -6.672408 -1.014911 -0.346191 37 9 0 1.451535 -1.622579 -1.949697 38 9 0 1.514367 -4.316464 -1.917321 39 9 0 0.197152 -5.696606 0.026469 40 9 0 -1.180475 -4.353232 1.955993 41 9 0 -1.235456 -1.650886 1.947792 42 9 0 3.041719 1.377980 -1.916011 43 9 0 5.627444 0.597768 -1.752338 44 9 0 6.474175 -0.858029 0.385745 45 9 0 4.727845 -1.526970 2.362965 46 9 0 2.149615 -0.748090 2.214367 ------

221