ABSTRACT Investigating Dimeric Boroles As Sources of Monomers

ABSTRACT

Investigating Dimeric Boroles As Sources of Monomers

Jessica J. Baker, M.S.

Mentor: Caleb D. Martin, Ph.D.

Boroles are 4π electron, antiaromatic, BC4 systems that boast an array of interesting reactivity including ring expansion, ring opening, and Diels-Alder. The majority of publications in the last 10 years have been focused on the reactivity of monomeric boroles while dimeric boroles, which lack the bulky aryl substituents on the butadiene backbone, have been left largely unexplored. 1-Phenyl-2,3,4,5-tetramethylborole was synthesized in

1988 by Fagan and coworkers and is a borole dimer which can be utilized as a monocylic borole unit upon “cracking,” much like a cyclopentadiene dimer. Only four papers have been published on the reactivity of the 1-phenyl-2,3,4,5-tetramethylborole dimer since its synthesis 30 years ago. This thesis details the investigation of the reactivity of the 1-phenyl-

2,3,4,5-tetramethylborole dimer and its ability to act as a monomer upon “cracking” at higher temperatures. Investigating Dimeric Boroles as Sources of Borole Monomers

Jessica Baker, B.A.

A Thesis

Approved by the Department of Chemistry and Biochemistry

Patrick Farmer, Ph.D., Chairperson

Submitted to the Graduate Faculty of Baylor University in Partial Fulfillment of the Requirements for the Degree of Master of Science

Approved by the Thesis Committee

Caleb D. Martin, Ph.D., Chairperson

Patrick Farmer, Ph.D.

Kevin K. Klausmeyer, Ph.D.

John L. Wood, Ph.D.

William Hockaday, Ph.D.

Accepted by the Graduate School December 2018

J. Larry Lyon, Ph.D., Dean

TABLE OF CONTENTS

LIST OF FIGURES ...... vi LIST OF TABLES ...... x LIST OF SCHEMES ...... xi ACKNOWLEDGMENTS ...... xiii DEDICATION ...... xv CHAPTER ONE ...... 1 An Introduction to Borole Chemistry ...... 1 1.1 Borole Monomers ...... 1 1.2 Borole Dimers ...... 3 1.3 Reactivity of Boroles ...... 9 1.4 Diels-Alder Reactivity of Boroles ...... 9 1.5 Ring Insertion ...... 12 CHAPTER TWO ...... 16 Diverse Reactivity of Dienes with Pentaphenylborole and 1-Phenyl-2,3,4,5- Tetramethylborole Dimer ...... 16 2.1 Abstract ...... 16 2.2 Introduction ...... 16 2.3 Results and Discussion ...... 19 2.4 Conclusion ...... 27 2.5 Experimental ...... 27 CHAPTER THREE ...... 34 1,2- and 1,1-Insertion Chemistry with Borole Dimers ...... 34 3.1 Introduction ...... 34 3.2 1,2-Dipolar Insertion of Benzophenone into Borole Dimers ...... 37 3.3 Sulfur Insertion into 1-Phenyl-2,3,4,5-Tetramethylborole Dimer to make 1,2- Thiaborine ...... 40 3.4 Conclusions ...... 44 3.5 Experimental ...... 44 APPENDICES ...... 48 APPENDIX A ...... 49 Supplementary Information for Chapter Two ...... 49 APPENDIX B ...... 91 Cartesian Coordinates of Optimized Geometries for Chapter Two ...... 91 APPENDIX C ...... 105 Supplementary Information for Chapter Three ...... 105

iv BIBLIOGRAPHY ...... 122

LIST OF FIGURES

Figure 1.1. Structure of boroles displaying the butadiene backbone, 4π antiaromatic character, and empty pz orbital on the boron atom ...... 1

Figure 1.2. Examples of alkenes and dienes that were reacted with 1-phenyl-2,3,4,5- tetramethylborole and their boranorbornene products 1.38 – 1.40 ...... 11

Figure 1.3. Illustration of organic (1.40), inorganic (1.41), and hybrid inorganic/organic (1.42) molecules ...... 14

Figure 2.1. Examples of monomeric boroles kinetically stable to dimerization ...... 17

Figure 2.2. Solid-state structure of 3 ...... 20

Figure 2.3. Solid-state structure of 4·pyr ...... 23

Figure 2.4. Solid-state structure of 5 ...... 26

Figure 3.1. Illustration of organic, inorganic, and hybrid inorganic/organic molecules ...35

Figure 3.2. Solid-state structure of 3.16 ...... 39

1 Figure 3.3. Stacked in situ H NMR spectra of the reaction of 3.14 with S8 ...... 41

Figure 3.4. Observed 11B{1H} NMR spectroscopic resonances of η6 boron complexes ...43

Figure 3.5. Solid-state structure of 3.22 ...... 43

1 Figure A-1. H NMR Spectrum of 3 in CDCl3 (*n-pentane) ...... 49

1 Figure A-2. Expansion of H NMR Spectrum of 3 in CDCl3 (aryl region) ...... 50

1 Figure A-3. Expansion of H NMR Spectrum of 3 in CDCl3 (aliphatic region, *n- pentane) ...... 51

13 1 Figure A-4. C{ H} NMR Spectrum of 3 in CDCl3 (*n-pentane) ...... 52

13 1 Figure A-5. Expansion of C{ H} NMR Spectrum of 3 in CDCl3 (aryl region) ...... 53

Figure A-6. FT-IR Spectrum of 3 ...... 54

vi 1 Figure A-7. H NMR Spectrum of 4 in C6D6 (*dichloromethane) ...... 55

1 Figure A-8. Expansion of H NMR Spectrum of 4 in C6D6 (aryl region) ...... 56

1 Figure A-9. Expansion of H NMR Spectrum of 4 in C6D6 (aliphatic region) ...... 57

13 1 Figure A-10. C{ H} NMR Spectrum of 4 in C6D6 ...... 58

13 1 Figure A-11. Expansion of C{ H} NMR Spectrum of 4 in C6D6 (aryl region) ...... 59

11 1 Figure A-12. B{ H} NMR Spectrum of 4 in C6D6 ...... 60

Figure A-13. FT-IR Spectrum of 4 ...... 61

1 Figure A-14. H NMR Spectra of 4×pyr in C6D6 at 25 ºC and 65 °C ...... 62

1 Figure A-15. H NMR Spectrum of 4×pyr in C6D6 at 65 °C ...... 63

1 Figure A-16. Expansion of H NMR Spectrum of 4×pyr in C6D6 at 65 ºC (aryl region) ..64

1 Figure A-17. Expansion of H NMR Spectrum of 4×pyr in C6D6 at 65 ºC (aliphatic region) ...... 65

13 1 Figure A-18. C{ H} NMR Spectrum of 4×pyr in C6D6 at 65 ºC ...... 66

11 1 Figure A-19. B{ H} NMR Spectrum of 4×pyr in C6D6 ...... 67

Figure A-20. FT-IR Spectrum of 4×pyr ...... 68

1 Figure A-21. H NMR Spectrum of 2 in C6D6 (*hexanes, #grease) ...... 69

1 Figure A-22. Expansion of H NMR Spectrum of 2 in C6D6 (aryl region) ...... 70

1 Figure A-23. Expansion of H NMR Spectrum of 2 in C6D6 (aliphatic region, *hexanes) ...... 71

13 1 Figure A-24. C{ H} NMR Spectrum of 2 in C6D6 ...... 72

11 1 Figure A-25. B{ H} NMR Spectrum of 2 in C6D6 ...... 73

Figure A-26. FT-IR Spectrum of 2 ...... 74

1 Figure A-27. H NMR Spectrum of 2×pyr in CDCl3 ...... 75

1 Figure A-28. Expansion of H NMR Spectrum of 2×pyr in CDCl3 (aryl region) ...... 76

vii 1 Figure A-29. Expansion of H NMR Spectrum of 2×pyr in CDCl3 (aliphatic region) ...... 77

13 1 Figure A-30. C{ H} NMR Spectrum of 2×pyr in CDCl3 ...... 78

13 1 Figure A-31. Expansion of C{ H} NMR Spectrum of 2×pyr in CDCl3 (aryl region) .....79

11 1 Figure A-32. B{ H} NMR Spectrum of 2×pyr in CDCl3 ...... 80

Figure A-33. FT-IR Spectrum of 2×pyr ...... 81

1 Figure A-34. H NMR Spectrum of 5 in CDCl3 (*n-pentane) ...... 82

1 Figure A-35. Expansion of H NMR Spectrum of 5 in CDCl3 (aryl region) ...... 83

1 Figure A-36. Expansion of H NMR Spectrum of 5 in CDCl3 (aliphatic region, *n- pentane) ...... 84

13 1 Figure A-37. C{ H} NMR Spectrum of 5 in CDCl3 (*n-pentane) ...... 85

13 1 Figure A-38. Expansion of C{ H} NMR Spectrum of 5 in CDCl3 (aryl region) ...... 86

11 1 Figure A-39. B{ H} NMR Spectrum of 5 in CDCl3 ...... 87

Figure A-40. FT-IR Spectrum of 5 ...... 88

Figure A-41. Solid-state structure of 2·pyr ...... 90

1 Figure C-1. H NMR Spectra of 3.16 in CDCl3 at 25 ºC and -40 °C ...... 105

1 Figure C-2. Expansion of H NMR Spectra of 3.16 in CDCl3 at 25 ºC and -40 ºC (aryl region) ...... 106

1 Figure C-3. H NMR Spectrum of 3.16 in CDCl3 at -40 ºC ...... 107

1 Figure C-4. Expansion of H NMR spectrum of 3.16 in CDCl3 at -40 ºC (aryl region) ..108

13 1 Figure C-5. C{ H} NMR Spectrum of 3.16 in CDCl3 ...... 109

13 1 Figure C-6. Expansion of C{ H} NMR spectrum of 3.16 in CDCl3 (aryl region) ...... 110

11 Figure C-7. B NMR Spectrum of 3.16 in C6D6 ...... 111

Figure C-8. FT-IR Spectrum of 3.16 ...... 112

1 Figure C-9. H NMR Spectrum of 3.19 in CDCl3 ...... 113

viii 1 Figure C-10. Expansion of H NMR Spectrum of 3.19 in CDCl3 ...... 114

13 1 Figure C-11. C{ H} NMR Spectrum of 3.19 in CDCl3 ...... 115

13 1 Figure C-12. Expansion of C{ H} NMR Spectrum of 3.19 in CDCl3 (aryl region) .....116

11 1 Figure C-13. B{ H} NMR Spectrum of 3.19 in CDCl3 ...... 117

Figure C-14. FT-IR Spectrum of 3.19 ...... 118

11 1 Figure C-15. B{ H} NMR Spectrum of 3.22 in CDCl3 ...... 119

Figure C-16. FT-IR Spectrum of 3.22 ...... 120

LIST OF TABLES

Table A-1. X-ray crystallographic details for compounds 3, 4×pyr, 2×pyr, and 5 ...... 89

Table C-1. X-ray crystallographic details for compound 3.16 and 3.22 ...... 121

LIST OF SCHEMES

Scheme 1.1. Synthesis of pentaphenylborole 1.4 via a stannole intermediate 1.3 ...... 2

Scheme 1.2. Reaction of pentaphenylborole 1.4 with diphenylacetylene to generate boranorbornadiene 1.5 and borepin ring 1.6 ...... 2

Scheme 1.3. The reversible dimerization of cyclopentadiene 1.7 ...... 3

Scheme 1.4. Formation of the spirocyclic dimer products of 1-chloro- and 1-bromo- 2,3,4,5-tetraphenylborole with gentle heating ...... 4

Scheme 1.5. Synthesis of the chloroborole dimer 1.14 ...... 5

Scheme 1.6. Proposed mechanism for the formation of the bridged bicyclic dimer 1.14 ...6

Scheme 1.7. Synthesis of diisopropylaminoborole 1.18 as well as the discovery of the diisopropylaminoborole Diels-Alder product 1.20 by exposure to SnCl2 ...... 6

Scheme 1.8. Reactions of the diisopropylaminoborole dianion 1.18 with organometallic- dihalides to form metal complexes 1.21 and 1.22 ...... 7

Scheme 1.9. Synthesis of 1-phenyl-2,3,4,5-tetramethylborole dimer 1.26 ...... 8

Scheme 1.10. Reaction of 1-phenyl-2,3,4,5-tetramethylborole dimer 1.26 with 2-butyne .9

Scheme 1.11. Mechanism for the formation of 1.5 and 1.6 ...... 10

Scheme 1.12. Reaction of 1.34 with 2-butyne and the coordination of IMe to give 1.32 .10

Scheme 1.13. Mechanism for the formation of 1,2-azaborine 1.39 from 1.4 supported by computational studies ...... 13

Scheme 1.14. Synthesis of 1,2-oxaborine 1.45 through the addition of NMMO to 1.4 ....14

Scheme 2.1. Examples of dimeric boroles (C2 and E2) that demonstrate thermal reactivity consistent with monomeric species ...... 18

Scheme 2.2. Thermal reactions of E2 with 1,3-butadiene and 1,3-cyclohexadiene. reported by Fagan and coworkers ...... 19

Scheme 2.3. Mechanism for the formation of 3 ...... 21

xi Scheme 2.4. Cracking E2 to form the monomeric species E and the mechanism of formation of 4×pyr ...... 24

Scheme 2.5. Diels-Alder cycloadditions of E and A with 1,3-cyclohexadiene to form boranorbornene products 2 and 5...... 26

Scheme 3.1. Synthesis of 1,2-thiaborine 3.4 thru the synthesis of 1,2-thiaborolide 3.9 by Ashe ...... 36

Scheme 3.2. Synthesis of 1,2-thiaborine 3.12 by the Martin lab ...... 36

Scheme 3.3. Reaction of pentaphenylborole and benzophenone to give the 1,2-insertion product, 3.13 ...... 37

Scheme 3.4. Reaction of 1-phenyl-2,3,4,5-tetramethylborole 3.14 with benzophenone ...38

Scheme 3.5. Mechanism for the formation of 3.16...... 39

Scheme 3.6. Formation of 1,2-thiaborine 3.19 by reacting 3.14 with elemental sulfur at 100 ºC ...... 41

Scheme 3.7. Haptotropic migration of 1,2-azaborine chromium complex 3.21 to form 3.23 upon heating ...... 44

xii

ACKNOWLEDGMENTS

First and foremost, I want to thank my committee: Drs. Patrick Farmer, Kevin K.

Klausmeyer, John L. Wood, and William Hockaday. You’ve taken the time out of your busy schedules to help progress me as a chemist and I would not have been able to succeed without your guidance.

To my mentor, Caleb: thank you for your patience and your leadership. There were times during my time in your group when I wasn’t sure which direction to go or how to best approach a problem. You offered both a fresh point of view to consider and the space that I needed to grow as an individual and a chemist. I greatly appreciate the time that you’ve put into me.

Mom, you are the strongest person I have ever met. I wouldn’t be the person I am today without your guidance and love. Thank you for always listening and encouraging me. Dad, you are a light. You taught me about love, laughter, and curiosity. Thank you!

Dustin, I’m so lucky to have you as a big brother. Thank you for being my rock and for always supporting me.

Amanda, you are going to do great things. Thank you for being my friend, for always being ready to fight for me, and for laughing with me. Your support has kept me afloat this last year. Marina, Megan, and Raegyn – Thank you for always being ready to celebrate my successes and to build me up when things don’t go how I planned. I love you all and you’ve made my time here amazing!

xiii To the post docs that I’ve overlapped within the group, Kiran and Alba: Kiran, you were patient and always encouraging. I learned a lot from you in my first year, and I was never afraid to ask you for advice. Alba, thank you for listening. It means more to me than you’ll ever know.

Clinton and Vanessa, you two are amazing. I’m so glad that I got to work in the same hallway as you, because I’m quite sure graduate school would not have been the same without your mentorship and friendship.

Leif, you have been a calm and steady voice of reason for me this past year. You are consistent, kind, and I’m so thankful for all of your help and all of the support you’ve given me.

Jesse, you are going to be a kick-ass chemist someday (not that you aren’t already).

There’s been nothing greater than watching you grow and mature in this lab to become that chemist. Our lab is consistently full of laughter and joy because you’re in it.

Kristen, I love you. You are a joy to be around and you inspire me so much. I am so proud of the growth that I have seen in you in this past year. I never expected to find a friend like you: I didn’t think people who are so selfless and loving actually existed in the world. Don’t let anything get in the way of accomplishing the amazing things that you’re going to do in life. Thank you for loving and supporting me.

Sam, you have been my rock, my confidant, my mentor, and my best friend since moving to Waco. I strive to have the tenacity, work-ethic, and strength that you have, as well as the deep love you show for the people in your circle. The wisdom and advice you have given me these past two and a half years will stay with me for the rest of my life, and

I’m so excited to see all of the great and amazing things that you will do.

xiv

DEDICATION

To my friends, family, and, most importantly, my cat, Nebula

CHAPTER ONE

An Introduction to Borole Chemistry

Boroles are 5-membered BC4 rings with 1,3-butadiene backbones that resemble cyclopentadiene.1-2 These molecules have the ability to act as Lewis acceptors for coordination due to the empty pz orbital located on the boron atom (Figure 1.1). The presence of the 1,3-butadiene backbone allows boroles to act as dienes and, as will be discussed later, as dienophiles. Finally, the antiaromatic character of this system makes for a very reactive species which can undergo facile transformations to create more complex products.3-23

Figure 1.1. Structure of boroles displaying the butadiene backbone, 4π antiaromatic character, and empty p orbital on the boron atom. z

1.1 Borole Monomers

Eisch and coworkers reported the synthesis of the first borole, pentaphenylborole

(1.4), in 1969.24 A stannole intermediate (1.3) was first made by reacting two equivalents of diphenylacetylene (1.1) and two equivalents of lithium metal to form the dilithio- compound 1.2. Addition of dimethyltindichloride (Me2SnCl2) gave 1.3 which was then

1 transmetallated with PhBCl2 to form 1.4 (Scheme 1.1). Pentaphenylborole is marked by its characteristic deep blue color and its extreme air and water sensitivity.

Scheme 1.1. Synthesis of pentaphenylborole 1.4 via a stannole intermediate 1.3.

Eisch explored the reactivity of 1.4 with diphenylacetylene and observed the ability of boroles to act as dienes in Diels-Alder type reactions. These products, called boranorbornadienes (1.5 in Scheme 1.2), give pseudo-5-coordinate boron centers, due to the Lewis-base coordination of the alkene of the boranorbornadiene backbone to the empty pz orbital of the central boron atom. Along with this, Eisch also observed the insertion of diphenylacetylene to give a 7-membered borepin ring (1.6) when 1.5 was heated.24-27

Scheme 1.2. Reaction of pentaphenylborole 1.4 with diphenylacetylene to generate boranorbornadiene 1.5 and borepin ring 1.6.

2 Pentaphenylborole was the first free borole characterized by X-ray crystallography and offered insight into the antiaromatic character of 1.4.28 The X-ray structure contained positional disorder within the unit cell due to the inability to differentiate between the boron and the carbon atoms of the central ring. However, the electron deficient boron atom seemed to be stabilized by π donation from adjacent phenyl rings within the crystal lattice, indicating that the bulky aryl groups help to stabilize the free borole. This result sparked the recent interest in boroles and led to the synthesis of boroles with varying substituents on both the boron and the carbon ring.16, 23, 29-42

1.2 Borole Dimers

The cyclopentadiene anion, generated upon deprotonation of the cyclopentadiene dimer, has been used as a universal reagent in metal complex synthesis. The protonated species exists as a dimer (1.8) but the monomeric unit (1.7) can be isolated for a limited time by distillation for reactions (Scheme 1.3).43-46

Scheme 1.3. The reversible dimerization of cyclopentadiene 1.7.

Boroles which lack the stabilizing steric bulk of aryl groups on their backbones tend to form dimers, much like cyclopentadiene. There are two different types of borole dimers: reversible dimers which can be “cracked” with heating and irreversible dimerization products that cannot access the original monomeric unit for further reactivity.34, 42, 47-51

3 There are two subtypes of irreversible borole dimers: spirocyclic dimer products and bridged bicyclic dimer products. The former was observed by Braunschweig and coworkers in 2010 and 2011 in an effort to synthesize a borole with a halide, allowing it to undergo substitution at the central boron atom. Braunschweig successfully synthesized and fully characterized this type of borole as a monomer.34, 49 However, gentle heating (40 ºC for 1-chloro-2,3,4,5-tetraphenylborole or 55 ºC for 1-bromo-2,3,4,5-tetraphenylborole) of

1.9 resulted in the formation of the irreversible spirocyclic dimer (1.10) (Scheme 1.4).

Scheme 1.4. Formation of the spirocyclic dimer products of 1-chloro- and 1-bromo-2,3,4,5- tetraphenylborole with gentle heating.

In 2016, Marder and coworkers discovered the bridged bicyclic dimer product

(1.14) in their attempts to synthesize the chloroborole monomer (1.13) (Scheme 1.5).50

Transmetallating from the corresponding zirconacycle (1.11) to the stannole (1.12) was accomplished by methods similar to Piers and coworkers’ synthesis of perfluoropentaphenylborole.30 Final transmetallation from the stannole to the borole yielded unexpected results: initial addition of BCl3, done at -78 ºC, gave an immediate color change from the green of the stannole starting material to a brown/purple color, but allowing the solution to warm to room temperature resulted in the loss of this color. NMR spectroscopy and crystallographic analysis revealed the presence of the bridged bicyclic dimer product (1.14). It was later theorized that the desired chloroborole monomer (1.13)

4 was formed initially, but that the resulting monomer was too unstable at room temperature, and dimerized to form 1.14.

Scheme 1.5. Synthesis of the chloroborole dimer 1.14.

Computational analysis of the mechanism of formation showed that this reaction proceeded from an initial [2� + 2π] cyclization to form a 5/7 fused ring intermediate (1.15)

(Scheme 1.6). A zwitterionic intermediate is formed by first making a new B–C bond from one of the adjacent alkenes. Breaking of the B–C bond closest to the new carbocation formed in intermediate 1.16 results in the 6/7-bridged bicyclic dimer product (1.14).

Further computations on the formation of borole dimers were published in 2017 in a collaboration between Lin, Marder, and Braunschweig, which proposed a similar mechanism for the formation of the spirocyclic dimers beginning with a [2� + 2π] cyclization. 51

The first example of a [4 +2] borole dimer was observed by Herberich and coworkers in their efforts to synthesize an unsubstituted borole for metal complexation.

Diisopropylaminoborole (1.18) was first reported by Herberich in 1983 as a dianion, which was reportedly air-sensitive, decomposed at room temperature, and was synthesized from

1-diisopropylamino-3-borolene (1.17).52 In 1985, Herberich discovered that 1.18

5 underwent a Diels-Alder type dimerization to form 1.20 when exposed to SnCl2 (Scheme

1.7).47

Scheme 1.6. Proposed mechanism for the formation of the bridged bicyclic dimer 1.14.

Scheme 1.7. Synthesis of diisopropylaminoborole 1.18 as well as the discovery of the diisopropylaminoborole Diels-Alder product 1.20 by exposure to SnCl2.

6 The formation of the 1.20 in situ did not stop the reactivity of 1.18, as Herberich and coworkers surmised that the borole dimer was formed when reacted with any organometallic-dihalide compounds. In fact, if these organometallic-dihalides were transition metals, they could form metal complexes with the diisopropylaminoborole monomer (1.19), as shown in the formation of complexes 1.21 and 1.22 (Scheme 1.8).47, 53

X-ray crystallography studies of these structures revealed that the diisopropylaminoborole was not binding as an η5 ligand, but instead as an η4 ligand. The lone pair of the nitrogen atom donates into the empty pz orbital of the boron atom, pulling it out of planarity and away from full interaction with the metal center. This η4-coordination was not observed in the metal-borole complexes that Herberich had synthesized directly from unsubstituted borolenes with alkyl or aryl substituents on the boron atom.54-59

Scheme 1.8. Reactions of the diisopropylaminoborole dianion 1.18 with organometallic-dihalides to form metal complexes 1.21 and 1.22.

Another example of a Diels-Alder borole dimer was reported by Fagan and coworkers in 1988 (Scheme 1.9).48, 60 1-Phenyl-2,3,4,5-tetramethylborole dimer (1.26) was first synthesized through a red tetramethyl-zirconacycle (1.24), made by addition of 2-

7 butyne (1.23), n-butyl lithium, and biscyclopentadienyl-zirconocenedichloride.

Transmetallation of zirconium to boron with PhBCl2 produced 1-phenyl-2,3,4,5- tetramethylborole (1.25) which dimerized at room temperature to 1.26, denoted by the presence of two resonances in the 11B{1H} NMR spectrum at 70.0 and -6.5 ppm. The two different resonances were the results of the different coordination environments of the two boron atoms, distinguished by the coordination of the alkene backbone to the empty pz orbital of one of the boron atoms.61-62 The interaction of the boron atom with the alkene of the backbone was also observed in the crystal structure by the bending of the boron atom towards the backbone.

Scheme 1.9. Synthesis of 1-phenyl-2,3,4,5-tetramethylborole dimer 1.26.

Fagan and coworkers demonstrated the ability of 1.26 to reversibly reform the monomer (1.25) by trapping the monomer with 2-butyne at 60 ºC to give Diels-Alder product 1.27 (Scheme 1.10).48 This not only showed that 1-phenyl-2,3,4,5- tetramethylborole was a reversible dimer, much like cyclopentadiene and diisopropylaminoborole, but also that borole dimers can undergo similar reactivity to monomeric boroles with bulkier substituents, such as pentaphenylborole.

Scheme 1.10. Reaction of 1-phenyl-2,3,4,5-tetramethylborole dimer 1.26 with 2-butyne.

1.3 Reactivity of Boroles

Boroles can react in several different ways: Diels-Alder reactivity, coordination, redox chemistry, ring insertion, and ring opening.1-16, 18-19, 21-27, 30-36, 38, 40-42, 48-50, 63-78 The butadiene backbone of borole allows it to act as a proficient diene in Diels-Alder type cyclizations when exposed to dienophiles. The empty pz orbital on boron allows boroles to coordinate to Lewis bases, which can lead to further reactivity. Finally, the nucleophilic

B–C bond of the borole can break (ring opening) to insert the coordinated atom (ring insertion). For the purpose of this thesis, only Diels-Alder and ring insertion reactivity will be discussed.

1.4 Diels-Alder Reactivity of Boroles

The first type of reactivity reported with boroles was the [4 + 2] cycloaddition of diphenylacetylene and 1.4 by Eisch and coworkers in 1969.24 This was followed by subsequent work examining 1.4 as a diene, forming the boranorbornadiene product (1.5), which can be heated to form borepin 1.6 through a 1,3-suprafacial sigmatropic rearrangement of intermediate 1.28 (Scheme 1.11).25-27 The boranorbornadiene product 1.5 can be identified by the presence of the pseudo-5-coordinate boron center observed by

11B{1H} NMR spectroscopy as a sharp peak between 10 and -20 ppm.48, 61, 64, 68, 73

9 Scheme 1.11. Mechanism for the formation of 1.5 and 1.6.

Borepins are characterized as 7-membered nonaromatic rings with a central boron

atom and garnered some interest for their use in the generation of aromatic ring systems

upon elimination of the boron atom.79 Though borepin 1.6 is more thermally stable in the

1.4 and diphenylacetylene reaction, the boranorbornadiene ring (1.27) is the only product formed in the reaction of 1.26 and 2-butyne (Scheme 1.10).48

Scheme 1.12. Reaction of 1.34 with 2-butyne and the coordination of IMe to give 1.32.

Changing the substituents of the alkyne to be different than those on the carbon

backbone of the boroles gave further insight into the reactivity of boroles. For example, the

reaction of 1-mesityl-2,3,4,5-tetraphenylborole (1.29) with 2-butyne revealed that the

boranorbornadiene product can also form as two different constitutional isomers, 1.30 and

1.31 (Scheme 1.12).68 Braunschweig and coworkers proposed that 1.30 was the kinetic isomer, while 1.31 was the thermodynamic isomer, due to the equilibration of the ratio of

10 the two isomers converting from 1:2.4 to 1:9 over two days. Addition of the N-heterocyclic

carbene N,N’-dimethylimidazol-2-ylidene (IMe) and heating led to the generation of the

coordinated borepin product 1.32 as a single isomer.

Figure 1.2. Examples of alkenes and dienes that were reacted with 1-phenyl-2,3,4,5-tetramethylborole and their boranorbornene products 1.33 – 1.35.

Outside of the reactivity of boroles and alkynes, Fagan and coworkers also explored

the chemistry of 1.26 and a variety of alkenes and two dienes (Figure 1.2).48 All of these

reactions gave boranorbornene products (examples: 1.33 – 1.35) supported by the observance of diagnostic 11B{1H} NMR spectroscopic resonances between the ranges of

10 to -20 ppm, indicating pseudo-5-coordinate boron centers. It is important to note that

11 Fagan and coworkers did not report any crystallographic data in the characterization of these products. In the 30 years since the synthesis of 1-phenyl-2,3,4,5-tetramethylborole, only one other paper utilizes the dimer as a reactant.80

1.5 Ring Insertion

The ability of boroles to form adducts with dipolar molecules was studied extensively in the years following the publication of the X-ray crystal structure of 1.4. In

2012, Piers and coworkers observed the ability of carbon monoxide to form an adduct with both 1.4 and perfluoropentaphenylborole at low temperatures.3 Both Braunschweig and

Martin reported on the reactivity of 1.4 with azides in 2014.5-6 The 6-membered 1,2- azaborine product (1.39) was isolated and identified by 11B{1H} NMR spectroscopy and

X-ray crystallography by Braunschweig, and an intermediate of the reaction was isolated and found to be a 1:2 azide to borole, 8-membered BN3C4 ring (1.38) by Martin.

Computational studies gave insight into the mechanism of formation for the 1,2-azaborine product (1.39) (Scheme 1.13). A borole/azide adduct intermediate (1.36) was formed first, which can readily form a bicyclic intermediate (1.37). This bicyclic intermediate can either convert to the cyclooctatetraene ring (1.38) observed by X-ray crystallography or directly into the 1,2-azaborine product (1.39). The ability of boroles to first coordinate to a dipole within an adjacent molecule and then undergo ring expansion to form a 6-membered ring has also been explored and has been utilized with monomeric borole units to form 6-, 7-, and even 8-membered heterocycles.3, 5-12, 14, 16-17, 22-23, 64, 74-76

12 Scheme 1.13. Mechanism for the formation of 1,2-azaborine 1.39 from 1.4 supported by computational studies.

This observed ability of boroles to undergo 1,1-insertion reactions to give 6-

membered heterocycles garnered a large amount of interest due to their ability to create compounds with close similarity to benzene (1.40), a uniquely stable and favorable molecule for a vast array of research possibilities. Borazine (1.41) is considered an

inorganic analogue of benzene, and compounds like 1,2-azaborine (1.42) have been

popular amongst main group chemists as potential hybrid inorganic/organic analogues of

benzene (Figure 1.3).81-85

As shown above, boroles offer a facile and efficient method to synthesize these hybrid inorganic/organic molecules by utilizing 1,1-insertion chemistry, and the Martin group has successfully utilized these methods to insert a variety of chalcogens and pnictogens into pentaphenylborole frameworks.5, 74-76 The 1,2-oxaborine product (1.45) has visible intermediate formation, as observed by 11B{1H} NMR spectroscopy with a 4-

13 coordinate B–adduct resonance at 6.4 ppm and the formation of a milky white precipitate upon addition of N-methylmorpholine-N-oxide (NMMO) to pentaphenylborole (Scheme

1.14).76 This peak at 6.4 ppm indicated the formation of the NMMO-borole adduct (1.44), which shifted to a 3-coordinate B–O peak at 38.4 ppm after reacting for another 30 minutes, upon elimination of N-methylmorpholine (1.46). X-ray crystallography revealed the 1,2- oxaborine species (1.45).

Figure 1.3. Illustration of organic (1.40), inorganic (1.41), and hybrid inorganic/organic (1.42) molecules.

Scheme 1.14. Synthesis of 1,2-oxaborine 1.45 through the addition of NMMO to 1.4.

The Martin group and others went on to examine the reactivity of other dipolar molecules such as isocyanates (RN=C=O), carbonyls (RC=O), diazo-compounds (N=NR), azides (N=N=NR), nitrones (R2C=NO), isothiocyanates (RN=C=S), and epoxides with 1.4 to show that these molecules can undergo ring expansion reactions.5-10, 12, 14, 17, 22 These

14 compounds can either perform 1,1-insertions (as is the case for diazo-compounds and

azides), 1,2-insertions (carbonyls, isocyanates, and isothiocyanates), or 1,3-insertions

(nitrones and epoxides), depending on the type of dipolar molecule used.

The ring insertion chemistry of boroles offers efficient methods to form 6-, 7-, and

8-membered ring systems for further synthesis and exploration. This thesis examines the

ability of 1-phenyl-2,3,4,5-tetramethylboroles ability to not only act as a monomeric borole

unit, but also reports the unique reactivity of a less sterically hindered borole.

CHAPTER TWO

Diverse Reactivity of Dienes with Pentaphenylborole and 1-Phenyl-2,3,4,5- Tetramethylborole Dimer

2.1 Abstract

The reactions of 2,3-dimethyl-1,3-butadiene and 1,3-cyclohexadiene with a monomeric borole and a dimeric borole were investigated. The monomeric borole reacted at room temperature whereas heat was required to crack the dimeric borole to form the monomer and induce reactivity. 2,3-Dimethyl-1,3-butadiene reacts to give diverse products resulting from a cycloaddition process with boroles acting as a dienophile, followed by rearrangements to furnish bicyclic species. For 1,3-cyclohexadiene, a classical [4 + 2] process is observed in which 1,3-cyclohexadiene serves as the dienophile and the boroles as the diene partner. The experimental and theoretical interrogation indicates that dienes undergo cycloaddition reactions with boroles, but can serve as a diene or dienophile.

2.2 Introduction

Diels-Alder reactions are a powerful method for constructing complex molecular architectures.86-88 In many systems, these reactions can be reversible with a ubiquitous example being the dimerization of cyclopentadiene. In this reaction, cyclopentadiene undergoes a bimolecular [4+2] dimerization with one equivalent acting as the diene and the other as the dienophile.43, 45-46 Upon heating, the retro Diels-Alder reaction (“cracking”) occurs to generate the monomer that can be isolated via fractional distillation and utilized as a reagent.44 The neutral boron analogue of cyclopentadiene, borole, features a

16 tricoordinate boron center in place of the tetracoordinate carbon. Given the unsaturation

and four pi-electrons in the planar ring, boroles are antiaromatic and high in

thermodynamic energy.1-2, 12 In recent years, research on boroles has primarily focused on

species with aryl groups on the carbon atoms adjacent to boron in the BC4 ring that kinetically stabilize the molecule, precluding dimerization or decomposition (e.g. A and B,

Figure 2.1).16, 23-24, 29-42, 51, 63, 89

Figure 2.1. Examples of monomeric boroles kinetically stable to dimerization.

If smaller substituents are on the carbon atoms, the molecule can undergo a [4 + 2] dimerization akin to cyclopentadiene. This was first observed in 1985 by Herberich upon

47 the preparation of 1-diisopropylaminoborole (C) which was isolated as the dimer (C2).

Upon heating the dimer with transition metal complexes bearing labile ligands, h5-borole

coordination compounds (D) were isolated, indicating that dimers can act as bottleable

sources of monomers (C, Scheme 1).53, 90 In 1988, Fagan and coworkers prepared the 1- phenyl-2,3,4,5-tetramethylborole dimer (E2), that upon heating in the presence of dienophiles, gave rise to products consistent with a retro Diels-Alder to the monomer (E) and a [4 + 2] reaction, further supporting the reversibility of borole dimerization.48, 60, 91

For reported boroles with halogen atoms on the boron center, irreversible dimerization or

17 decomposition is observed but not via [4 + 2] processes, preventing their use as sources of monomers.34, 49-50 The dimerization and decomposition is attributed to the high reactivity of boroles which readily react with many functional groups.3-21, 23, 92

Scheme 2.1. Examples of dimeric boroles (C2 and E2) that demonstrate thermal reactivity consistent with monomeric species.

Steric effects primarily dictate the propensity of boroles to undergo Diels-Alder

51 reactivity as evidenced by the kinetic reversibility of dimers C2 and E2. The addition of dienophiles to monomeric and dimeric boroles (alkenes, alkynes, phosphalkyne, and diazenes) results in [4 + 2] processes to furnish bicyclic products or rearrangements thereof.16-17, 24-27, 48, 64, 73, 77-78, 80, 93-95 The reactivity of dienes with boroles has been less studied with only two reported examples, both with a dimeric borole.48 One double bond of 1,3-butadiene and 1,3-cyclohexadiene thermally reacts as a dienophile with E2 to generate the boranorbornadiene frameworks 1 and 2, respectively (Scheme 2.2). This precedent indicates preferential diene over dienophile reactivity for E2. In this work, we explore the first reactions of a monomeric borole, pentaphenylborole (A), with dienes, namely 2,3-dimethyl-1,3-butadiene and 1,3-cyclohexadiene. The unexpected

18 transformations prompted investigations into the reactions of E2 with 2,3-dimethyl-1,3-

butadiene as well as to reexamine the corresponding reaction with 1,3-cyclohexadiene.

Scheme 2.2. Thermal reactions of E2 with 1,3-butadiene and 1,3-cyclohexadiene. reported by Fagan and coworkers.

2.3 Results and Discussion

The addition of 2,3-dimethyl-1,3-butadiene to a CDCl3 solution of A at room

temperature resulted in a color change from the deep blue of A to yellow. Monitoring the

reaction by 1H NMR spectroscopy indicated complete consumption of 2,3-dimethyl-1,3- butadiene after 30 min. Single crystals grown for X-ray diffraction studies identified the product as an unusual bicyclic BC4/BC5 fused ring system with a three coordinate trigonal planar boron atom [Sangles = 359.6(1)º] and a quaternary carbon at the ring junctions (3,

Figure 2.2). The newly constructed six membered BC5 ring is composed of the four carbons formerly of the diene and a B,C unit from the borole moiety. The lack of a phenyl group on boron suggests a migration occurred to the adjacent carbon as it bears two phenyl groups. The carbon-carbon bond derived from the two internal carbons of 2,3-dimethyl-

1,3-butadiene is consistent with a double bond [C(6)-C(7) 1.336(2) Å]. The short bond

19 distance between the two tricoordinate carbon atoms in the BC4 ring [C(2)–C(3) 1.348(2)

Å] confirms the 1-bora-cyclo-pent-3-ene ring system.4, 7, 13, 15, 19, 21, 65, 96

Figure 2.2. Solid-state structure of 3. Hydrogen atoms are omitted for clarity and ellipsoids depicted at the 50% probability level. Selected bond lengths (Å): B(1)–C(1) 1.601(2), C(1)–C(2) 1.551(2), C(2)– C(3) 1.348(2), C(3)–C(4) 1.527(2), C(4)–C(5) 1.544(2), C(5)–C(6) 1.517(2), C(6)–C(7) 1.336(2), C(7)– C(8) 1.521(2), C(8)–B(1) 1.549(2), B(1)–C(4) 1.573(2).

The formation of 3 was surprising given the literature precedent of E acting as a diene in the [4 + 2] reactions with 1,3-cyclohexadiene and 1,3-butadiene as well as studies reporting A reacting similarly with dienophiles (alkenes or alkynes). The reaction pathway was investigated using computational methods to rationalize the mechanism for the formation of 3. Geometries were optimized at the M06-2X/6-31+G(d) level of theory, with optimized parameters similar to the crystal structures. Reaction energetics were investigated from single-point DSDPBEP86/def2-TZVP energy calculations inclusive of toluene solvent effects. The results suggest a two-step process to form 3. First, 2,3- dimethyl-1,3-butadiene reacts with the B-C bond of A, facilitated by the diene backbone,

20 via a cycloaddition process with a DG of +12 kJ/mol to install the 5,6-fused core with a

carbocation adjacent to the quaternary anionic boron center (Int1, Scheme 2.3). The

intermediate is poised for a 1,2-aryl migration from the borate to the adjacent carbocation

to form 3, with a small barrier of 19 kJ/mol. The overall DGº of reaction is -93 kJ/mol

indicating a thermodynamically favorable product.

Scheme 2.3. Mechanism for the formation of 3 from DSDPBEP86/def2-TZVP. calculated reaction free energies (kJ/mol) inclusive of toluene solvent. Energies are given relative to the reactants.

To determine if this irregular borole reactivity was due to the diene or the borole,

the analogous reaction was investigated with E2. A toluene solution of E2 was added to a solution of two equivalents of 2,3-dimethyl-1,3-butadiene and stirred at room temperature.

No indication of reaction was observed by in situ 11B{1H} NMR spectroscopy, hence, the

reaction was heated to 100 ºC, a temperature reported to induce monomeric reactivity

(Scheme 2.2).48 11B{1H} NMR spectroscopy indicated the disappearance of the signals for

48, 60 E2 (-6.5 and 70.0 ppm) and the emergence of a major resonance at 87.1 ppm after 6 h.

1 Upon workup, an H NMR spectrum of the isolated yellow oil in CDCl3 revealed the disappearance of the vinylic protons of 2,3-dimethyl-1,3-butadiene at 5.04 and 4.93 ppm, with the emergence of aliphatic signals at 2.35 and 2.26 ppm, each integrating to two.

21 Attempts to crystallize the product were unsuccessful as a solid could not be obtained. Given the tricoordinate boron resonance, pyridine was added with the intent of generating a Lewis acid/base adduct that would likely be a solid. Gratifyingly, the adduct readily formed, evidenced by the tetracoordinate 11B{1H} NMR signal at 8.3 ppm, and permitted growth of single crystals for X-ray diffraction studies (4×pyr, Figure 2.3).

Interestingly, the product is a 5,5-spirocyclic system with a quaternary carbon shared between C5 and BC4 rings. Within the BC4 ring, the short C(2)–C(3) bond length of

1.335(2) Å is consistent with a double bond and the downfield shift of the base-free species,

4 (87.1 ppm), is reminiscent of 1-bora-cyclopent-3-ene heterocycles with different

4, 7, 13, 15, 21, 65, 96 substitution (range 71.7 – 81 ppm). Within the C5 ring, two adjacent methylenes are bound to the quaternary carbon and the short C-C bonds between the two methyl bearing carbons are consistent with a cycloaddition occurring with 2,3-dimethyl-

1,3-butadiene. The pyridine and methyl group bound to boron, as well as the phenyl group on the adjacent carbon, indicates a rearrangement occurred.

Probing the mechanism with computational methods revealed that cracking E2 to the monomer (E) has to overcome an energy barrier of 145 kJ/mol to initiate the reaction, with E being 90 kJ/mol higher in energy than E2 (Scheme 2.4). The mechanism and energetics for the cycloaddition to the 5,6-fused core (Int 2) followed by a 1,2-aryl migration from the B-Ph unit to the adjacent carbon to produce Int 3 are consistent for the analogous reaction with A to produce 3. The barrier to form Int 2 is 80 kJ/mol, with Int 2 being only marginally more stable than E. The 1,2-aryl migration from the borate to the adjacent carbocation has a very low energy barrier of 8 kJ/mol and gives Int 3 with a DGº of -109 kJ/mol relative to E. In this case, the reaction then proceeds with a 5,1-methyl

22 migration (Int 4) with an energy barrier of 110 kJ/mol. While sizable, the barrier is lower

than that calculated to crack the reactant dimer E2. The barrier for the formation of 4, which arises by bond metathesis from C–B to C–C to generate the spirocycle, is very modest at 4 kJ/mol, giving 4 with an overall DGº of -124 kJ/mol from E. Subsequent addition of

pyridine to form 4×pyr is exergonic, with the overall DGº for the formation of 4×pyr being

-141 kJ/mol from E.

Figure 2.3. Solid-state structure of 4×pyr. Hydrogen atoms are omitted for clarity and ellipsoids are depicted at the 50% probability level. Selected bond lengths (Å): B(1)–C(1) 1.681(2), C(1)–C(2) 1.528(2), C(2)–C(3) 1.335(2), C(3)–C(4) 1.525(2), C(4)–C(5) 1.568(2), C(5)–C(6) 1.505(2), C(6)–C(7) 1.328(2), C(7)–C(8) 1.504(2), C(8)–C(4) 1.559(2), C(4)–B(1) 1.654(2), B(1)–N(1) 1.654(2), B(1)–C(9) 1.618(2).

These unusual findings prompted us to reinvestigate Fagan’s reaction of 1,3-

cyclohexadiene and the dimeric borole E2 as well as its reactivity with A. In the reported

48 reaction of 1,3-cyclohexadiene with E2 an X-ray structured had not been included.

Performing the reaction in the same conditions (100 ºC in toluene for 27 h) revealed the

same major 11B{1H} resonance at -14.6 ppm, consistent with the boranorbornene product with the proximal olefin coordinating to the boron center in the bridgehead position.

23 Crystals suitable for X-ray diffraction could not be grown of the free species, therefore, a pyridine adduct was prepared and crystals grown confirmed the assignment made by Fagan as the pyridine adduct of the boranorbornene species, 2×pyr (S-34). This structure confirms the identity but positional disorder of the C=C double bond in the cyclohexene moiety prevents an in depth discussion on the metrical parameters.

Scheme 2.4. Cracking E2 to form the monomeric species E and the mechanism of formation of 4×pyr from E. Free energies are given relative to the reactants.

24 The stoichiometric reaction of A with 1,3-cyclohexadiene in dichloromethane

resulted in a color change from blue to yellow over a period of 1 h. After work up, the

1 isolated solids were dissolved in CDCl3 and acquiring an H NMR spectrum revealed the loss of two of the four vinylic protons. Acquiring a 11B{1H} NMR spectrum revealed a

resonance at -2.8 ppm, consistent with a four, or pseudo five coordinate boron center. Upon

obtaining single crystals for X-ray diffraction studies, the solid-state structure was

determined to be the boranorbornene species 5. The proximal C=C bond to the boron in

the bridgehead position coordinates to the vacant pz orbital on boron giving a pseudo five- coordinate boron center rationalizing the observed 11B{1H} NMR signal at -2.8 ppm. The

C(9)-C(10) bond is slightly elongated from a typical C=C double bond [1.381(2) Å c.f.

C(3)-C(4) 1.340(2)] and both of the corresponding B-C interactions are longer than single

bonds [B(1)–C(9) 1.984(2) and B(1)–C(10) 1.966(2) c.f. B(1)–C(1) 1.618(2) and B(1)–

C(8) 1.608(2)] consistent with an alkene interacting with an unsaturated boron center. Such

alkene-boron interactions have been reported in analogous 7-boranorbornene and 7-

boranorbornadiene complexes and the bonding has been modeled computationally.27, 62, 64,

68, 73, 97-98

Theoretical calculations on the reactions of A and E with 1,3-cyclohexadiene

support the proposed classic [4 + 2] Diels-Alder mechanism. The barrier for the

cycloaddition of E with 1,3-cyclohexadiene is 73 kJ/mol, much lower than the barrier to

crack the dimer (145 kJ/mol). The overall DG° values are -90 and -65 kJ/mol for E and A,

respectively. Alternative products were investigated theoretically, with the experimentally

observed Diels-Alder products thermodynamically favoured (see Supporting Information).

Similarly, [4 + 2] reactivity with 2,3-dimethyl-1,3-butadiene akin to 2 and 5 was

25 investigated, however, the isolated products are also thermodynamically favored based on the calculations.

Figure 2.4. Solid-state structure of 5. Hydrogen atoms are omitted for clarity. Ellipsoids are depicted at the 50% probability level. Selected bond lengths (Å): B(1)–C(1) 1.618(2), C(1)–C(2) 1.561(2), C(2)– C(3) 1.507(2), C(3)–C(4) 1.340(2), C(4)–C(5) 1.488(2), C(5)–C(6) 1.549(4), C(6)–C(7) 1.519(2), C(7)– C(2) 1.546(2), C(7)–C(8) 1.562(2), C(8)–C(9) 1.520(2), C(9)–C(10) 1.381(2), C(10)–C(1) 1.522(2), B(1)–C(8) 1.608(2), B(1)–C(9) 1.984(2), B(1)–C(10) 1.966(2).

Scheme 2.5. Diels-Alder cycloadditions of E and A with 1,3-cyclohexadiene to form boranorbornene products 2 and 5. Free energies are given relative to reactants.

26 2.4 Conclusion

This work presents the first comparison study between a monomeric and dimeric

borole. The reactivity of pentaphenylborole and 1-phenyl-2,3,4,5-tetramethylborole dimer

with two dienes (2,3-dimethyl-1,3-butadiene and 1,3-cyclohexadiene) demonstrated that

boroles can act as both dienes and dienophiles in pericyclic reactions. Both boroles reacted

via a mechanism with the B-C bond acting as a dienophile with 2,3-dimethyl-1,3-butadiene

whereas the C4 backbone in the borole reacted as the diene partner with 1,3- cyclohexadiene. The difference in reactivity between 2,3-dimethyl-1,3-butadiene and 1,3- cyclohexadiene is presumably influenced by the rigidity of the cyclic diene. The disclosed results unravel intricacies in the reactivity of dienes with boroles that may prove insightful into the stability of prospective borole targets.

2.5 Experimental

General Considerations. All manipulations were performed under an inert nitrogen atmosphere using standard Schlenk techniques or in a MBraun Unilab glovebox. Solvents were purchased from commercial sources as anhydrous grade, dried further using a JC

Meyer Solvent System with dual columns packed with solvent-appropriate drying agents, and stored over 4Å molecular sieves. A and E2 were prepared via the corresponding

literature procedures.24, 60 2,3-Dimethyl-1,3-butadiene and 1,3-cyclohexadiene were

purchased from Acros Organics and used as received. CDCl3 and C6D6 for NMR spectroscopy were purchased from Cambridge Isotope Laboratories and dried by stirring for 3 days over CaH2, distilled, and stored over 4Å molecular sieves. Multinuclear NMR spectra were recorded on a Bruker 600 MHz or 400 MHz spectrometer. FT-IR spectra were

27 recorded on a Bruker Alpha ATR FT-IR spectrometer on solid and oil samples. High-

resolution mass spectra (HRMS) were acquired at the University of Texas at Austin Mass

Spectrometry Center on a Waters Micromass AutoSpec Ultima GC/MS spectrometer using

CI. Melting points were measured with a Thomas-Hoover Unimelt capillary melting point

apparatus and are uncorrected. Single-crystal X-ray diffraction data were collected on a

Bruker Apex II-CCD detector using Mo Kα radiation (λ = 0.71073 Å). Crystals were

selected under Paratone oil, mounted on micromounts, and immediately placed in a cold

99 stream of N2. Structures were solved and refined using SHELXTL and figures produced

using OLEX2.100 All theoretical calculations were performed within the Gaussian 09 program.101 Geometry optimizations without symmetry constraints were carried out using the M06-2X density functional and the 6-31+G(d) basis set.102-104 Optimised structures

were characterized as either minima or transiton states through analytical calculation of the

Hessian (1 atm and 298 K). All DFT calculations were performed with an ultrafine

integration grid. The quadratic synchronous transit (QST) method was used to determine

transition states for the reaction pathway.105 All transition states were confirmed using intrinsic reaction coordinate (IRC) analysis, indicating relatedness between local minima structures.106 Single-point energy calculations were carried out at the M06-2X/6-31+G(d) optimized gemoetries, including both M06-2X and dispersion corrected double-hybride

DSDPBEP86 with the def2-TZVP basis set.107-109 Solvent effects with toluene solvent

parameters were investigated with the polarizable continuum model (PCM) self-consistent

reaction field (SCRF) together with Truhlar’s SMD solvation model.110-111 All reported �G values are DSDPBEP86/def2-TZVP or M06-2X/def2-TZVP electronic energies inclusive of solvent effects, with M06-2X/6-31+G(d) thermochemical corrections (gas phase),

28 defined as DSDPBEP86/def2-TZVP//M06-2X/6-31+G(d) and M06-2X/def2-TZVP//M06-

2X/6-31+G(d).

Synthesis of 3. A solution of 2,3-dimethyl-1,3-butadiene (76.0 µL, 0.672 mmol) in

CH2Cl2 (1 mL) was added to a solution of A (194.0 mg, 0.437 mmol) in CH2Cl2 (3 mL) and stirred for 30 min at 20 ºC to give a yellow solution. The volatiles were removed in vacuo, and the residue was washed with n-pentane (3 x 3 mL) and then dried to give an off-white solid. Yield: 160.0 mg, 69%. d.p. 164 – 167 °C. Single crystals for X-ray diffraction studies were grown by vapor diffusion of a CH2Cl2 solution of 3 into hexanes.

1 H NMR (600 MHz, CDCl3): d 7.36 (d, J = 6.0 Hz, 2H), 7.33 – 7.21 (m, 7H), 7.19 (t, J =

6.0 Hz, 1H), 7.14 – 7.10 (m, 3H), 7.09 – 6.99 (m, 8H), 6.98 – 6.93 (m, 4H), 2.89 (d, J =

18.0 Hz, 1H), 2.59 (d, J = 18.0 Hz, 1H), 1.81 – 1.63 (m, 5H), 1.50 (s, 3H). 13C{1H} NMR

(151 MHz, CDCl3): d 148.50 (Cq), 146.94 (Cq), 144.12 (Cq), 143.01 (Cq), 141.03 (Cq),

139.65 (Cq), 138.02 (Cq), 131.19 (CH), 130.70 (CH), 130.22 (CH), 129.42 (CH), 128.61

(CH), 128.58 (CH), 128.01 (CH), 127.81 (CH), 127.72 (CH), 127.64 (CH), 126.69 (CH),

126.53 (CH), 126.29 (CH), 126.05 (CH), 125.61 (Cq), 125.54 (CH), 66.30 (Cq), 54.60 (Cq),

-1 45.36 (CH3), 26.89 (CH3), 22.24 (CH2), 19.52 (CH2). FT-IR (cm (ranked intensity)): 1594

(9), 1488(7), 1439 (5), 1288 (11), 1182 (15), 1139 (10), 1098 (8), 1031 (6), 798 (13), 744

(2), 695 (1), 620 (12), 577 (14), 542 (4), 520 (3). High-resolution mass spectrometry

+ (HRMS) chemical ionization (CI): calcd for C40H35B [M] , 526.2832; found, 526.2841

Synthesis of 4. 2,3-Dimethyl-1,3-butadiene (405.0 µL, 3.579 mmol) was added to

a solution of E2 (640.0 mg, 1.630 mmol) in toluene (10 mL). The solution was heated to

100 ºC for 6 h in a pressure tube to give a dark yellow solution. The volatiles were removed in vacuo and the resulting yellow oil was distilled at 40 ºC under dynamic vacuum to give

29 the product as a colorless oil in >90% purity (by 1H NMR). Yield: 583.0 mg, 64%. 1H

NMR (600 MHz, C6D6): d 7.24 (t, J = 6.0 Hz, 2H), 7.17 – 7.13 (m, 2H), 7.06 (t, J = 6.0

Hz, 1H), 2.38 – 2.33 (m, 1H), 2.27 – 2.21 (m, 3H), 1.69 (s, 3H), 1.55 (s, 3H), 1.52 – 1.50

13 1 (m, 6H), 1.32 (s, 3H), 0.58 (s, 3H). C{ H} NMR (151 MHz, C6D6): d 145.27 (Cq), 140.90

(Cq), 137.84 (Cq), 133.97 (Cq), 130.77 (Cq), 130.40 (Cq), 128.84 (CH), 128.35 (Cq), 126.87

(CH), 125.17 (CH), 45.37 (CH2), 45.29 (CH2), 17.75 (CH3), 13.80 (CH3), 13.76 (CH3),

11 1 -1 10.89 (CH3), 10.40 (CH3). B{ H} NMR (192 MHz, C6D6): d 87.1 (br). FT-IR (cm

(ranked intensity)): 2909 (3), 2859 (9), 2825 (13), 1595 (14), 1491 (8), 1442 (5), 1378 (10),

1308 (2), 1208 (4), 1030 (6), 757 (11), 698 (1), 547 (7), 488 (12), 451 (15). High-resolution

+ mass spectrometry (HRMS) chemical ionization (CI): calcd for C20H27B [M] , 278.2206; found, 278.2211.

Synthesis of 4×pyr. Pyridine (57.0 µL, 0.708 mmol) was added to a colorless solution of 4 (195.0 mg, 0.699 mmol) in n-pentane (2 mL) at 20 ºC and resulted in an instantaneous color change to pale yellow. The reaction was stirred for 30 minutes, volatiles were removed in vacuo, and the yellow residue washed with n-pentane (5 x 1 mL) and dried to give a white solid. Yield: 163.0 mg, 65%, m.p. 103 – 106 ºC. Single crystals for X-ray diffraction studies were grown from storing the unpurified yellow residue of

1 4×pyr in n-pentane at 23 ºC. H NMR (400 MHz, C6D6, 65 °C): d 8.34 (d, J = 4.0 Hz, 2H),

7.11 – 6.99 (m, 4H), 6.90 (t, J = 8.0 Hz, 1H), 6.80 (t, J = 8.0 Hz, 1H), 6.42 (t, J = 8.0 Hz,

2H), 2.61 (d, J = 16.0 Hz, 1H), 2.43 (d, J = 12.0 Hz, 1H), 2.30 (d, J = 16.0 Hz, 1H), 2.19

(d, J = 12.0 Hz, 1H), 1.84 (s, 3H), 1.68 (s, 3H), 1.63 (s, 3H), 1.58 (s, 3H), 1.40 (s, 3H),

13 1 0.41 (s, 3H). C{ H} NMR (100 MHz, C6D6, 65 °C): d 147.84 (CH), 144.27 (Cq), 137.78

(CH), 136.98 (CH), 130.92 (Cq), 130.50 (Cq), 126.69 (CH), 123.42 (CH), 49.44 (CH2),

30 11 1 47.21 (CH2), 21.57 (CH3), 13.78 (CH3), 12.03 (CH3), 10.87 (CH3). B{ H} NMR (128

-1 MHz, C6D6): d 8.2. FT-IR (cm (ranked intensity)): 2855 (6), 1594 (13), 1492 (10), 1453

(2), 1295 (8), 1222 (9), 1074 (5), 1060 (14), 994 (11), 895 (12), 765 (3), 706 (7), 688 (1),

524 (4), 475 (15).

Synthesis of 2. The reaction conditions previously reported were utilized, reaction work up was modified, and characterization data omitted from the original paper have been

8 included as well as NMR spectroscopic data in C6D6 (literature was done in THF-d ). A solution of E2 (33.0 mg, 0.085 mmol) in toluene (3 mL) was added to a solution of 1,3- cyclohexadiene (18.0 µL, 0.189 mmol) in toluene (1 mL) and heated at 100 °C for 27 h in

a pressure tube. The volatiles were removed in vacuo, and the crude yellow oil was washed

with n-hexanes (3 x 3 mL) and dried to give 2 as a colorless oil in >90% purity (by 1H

1 NMR). Yield: 40.0 mg, 85%. H NMR (600 MHz, C6D6): d 7.29 (d, J = 6.0 Hz, 2H), 7.23

(t, J = 6.0 Hz, 2H), 7.20 – 7.16 (m, 1H), 5.87 (d, J = 6.0 Hz, 1H), 5.82 – 5.77 (m, 1H), 2.92

(d, J = 12.0 Hz, 1H), 2.71 – 2.64 (m, 1H), 1.77 – 1.67 (m, 3H), 1.56 (s, 6H), 1.36 (s, 3H),

13 1 1.30 (s, 3H), 1.18 – 1.10 (m, 1H). C{ H} NMR (151 MHz, C6D6): d 134.07 (CH), 130.01

(Cq), 127.69 (CH), 127.21 (CH), 49.46 (CH), 49.36 (CH), 24.93 (CH2), 23.74 (CH2), 14.91

11 1 (CH3), 14.88 (CH3), 12.51 (CH3), 12.44 (CH3). B{ H} NMR (192 MHz, C6D6): d -14.6.

FT-IR (cm-1 (ranked intensity)): 3016 (13), 2920 (2), 2866 (9), 1432 (4), 1379 (7), 1254

(6), 1066 (10), 930 (5), 751 (8), 733 (11), 699 (1), 634 (15), 591 (12), 518 (3), 441 (14).

High-resolution mass spectrometry (HRMS) chemical ionization (CI): calcd for C20H25B

[M]+, 276.2049; found, 276.2046.

Synthesis of 2×pyr. Pyridine (16.0 µL, 0.199 mmol) was added to a solution of 2

(53.0 mg, 0.193 mmol) in n-pentane (2 mL) at 20 ºC. An instantaneous color change from

31 colorless to dark yellow was observed and a yellow solid precipitated out of solution within

1 minute. The solution was decanted and the volatiles removed from the filtrate in vacuo to give a yellow solid in >90% purity (by 1H NMR). Yield: 64.0 mg, 93%, m.p. 88 – 91

°C. Single crystals for X-ray diffraction studies were grown via vapor diffusion of a

1 saturated solution of 2×pyr in Et2O into hexanes. H NMR (600 MHz, CDCl3): d 8.63 (d, J

= 4.0 Hz, 2H), 7.73 – 7.65 (m, 1H), 7.30 (t, J = 6.0 Hz, 2H), 7.22 – 7.17 (m, 5H), 5.79 –

5.75 (m, 1H), 5.74 – 5.70 (m, 1H), 2.82 (d, J = 12.0 Hz, 1H), 2.66 – 2.61 (m, 1H), 1.84 (s,

3H), 1.79 (s, 3H), 1.75 – 1.69 (m, 3H), 1.36 (s, 3H), 1.31 (s, 3H), 1.11 – 1.06 (m, 1H).

13 1 C{ H} NMR (151 MHz, CDCl3): d 149.81 (CH), 136.28 (CH), 133.79 (CH), 129.80

(CH), 127.65 (CH), 127.46 (CH), 126.76 (CH), 125.70 (Cq), 124.89 (Cq), 123.94 (CH),

49.09 (CH), 48.97 (CH), 24.64 (CH2), 23.49 (CH2), 14.83 (CH3), 14.78 (CH3), 12.79 (CH3),

11 1 -1 12.69 (CH3). B{ H} NMR (192 MHz, CDCl3): d -14.6. FT-IR (cm (ranked intensity)):

2920 (6), 1618 (15), 1452 (2), 1371 (14), 1210 (12), 1156 (10), 1077 (5), 904 (3), 818 (9),

771 (4), 749 (11), 733 (7) 709 (13), 697 (1), 583 (8).

Synthesis of 5. A solution of 1,3-cyclohexadiene (48.0 µL, 0.504 mmol) in CH2Cl2

(1 mL) was added to a blue solution of A (201.0 mg, 0.454 mmol) in CH2Cl2 (4 mL) and stirred for 1.5 h at 20 ºC to give a yellow solution. The volatiles were removed in vacuo and the residue was washed with n-pentane (3 x 3 mL) and dried to give a white solid.

Yield: 157.0 mg, 66%. d.p. 137 °C. Single crystals for X-ray diffraction studies were grown

1 by vapor diffusion of a CH2Cl2 solution of 5 into hexanes. H NMR (600 MHz, CDCl3): d

7.29 – 7.26 (m, 2H), 7.23 – 7.15 (m, 3H), 7.12 – 7.09 (m, 1H), 7.07 – 6.91 (m, 11H), 6.86

– 6.80 (m, 4H), 6.78 – 6.75 (m, 2H), 6.74 – 6.71 (m, 2H), 6.18 – 6.12 (m, 1H), 6.06 – 6.01

(m, 1H), 3.95 (d, J = 6.0 Hz, 1H), 3.46 – 3.38 (m, 1H), 2.12 – 2.05 (m, 1H), 2.02 – 1.93

32 13 1 (m, 2H), 1.62 – 1.55z (m, 1H). C{ H} NMR (151 MHz, CDCl3): d 139.73 (Cq), 139.66

(Cq), 135.62 (Cq), 134.87 (CH), 133.01 (Cq), 132.00 (CH), 131.35 (CH), 131.16 (CH),

130.58 (CH), 130.22 (CH), 129.28 (CH), 127.90 (CH), 127.68 (CH), 127.63 (CH), 127.50

(CH), 127.41 (CH), 127.37 (CH), 127.33 (CH), 127.26 (CH), 125.50 (CH), 124.87 (CH),

11 1 50.38 (CH2), 46.49 (CH2), 25.47 (CH), 23.79 (CH). B{ H} NMR (192 MHz, CDCl3): d

-2.9 (br). FT-IR (cm-1 (ranked intensity)): 2909 (15), 1597 (8), 1492 (6), 1441 (10), 1240

(7), 1077 (13), 1030 (9), 950 (12), 763 (3), 729 (5), 695 (1), 617 (14), 584 (2), 506 (4), 439

(11). High-resolution mass spectrometry (HRMS) chemical ionization (CI): calcd for

+ C40H33B [M] , 524.2675; found, 524.2692.

CHAPTER THREE

1,2- and 1,1-Insertion Chemistry with Borole Dimers

3.1 Introduction

A goal of the research in the Martin group has been to determine if dimeric boroles can be utilized as bottleable sources of monomeric boroles. The work described in the previous section (see Chapter 2) demonstrates that 1-phenyl-2,3,4,5-tetramethylborole and pentaphenylborole share similar reactivity pathways when exposed to dienes. In this respect, we have proven that 1-phenyl-2,3,4,5-tetramethylborole can not only be used as a source of monomeric borole units but also that the substitution of the aryl groups on the borole backbone leads to different reactivity. These encouraging results lead to the investigation of 1-phenyl-2,3,4,5-tetramethylborole dimer’s ability to undergo ring expansion reactivity to form larger heterocycles.

Benzene is the quintessential aromatic compound and is utilized for a wide array of chemistry.112 A nonaromatic, inorganic analogue of benzene is borazine, which replaces

C=C units with B–N units to produce an isoelectronic environment due to the interaction

81 of the lone pairs on the nitrogen atoms with the empty pz orbitals of the boron atoms. A system that is a hybrid inorganic/organic analogue of benzene is 1,2-azaborine (3.3), which embodies this unique motif and maintains the aromatic character and stability of benzene.83,

85 1,2-Azaborines have been explored substantially, but 1,2-thiaborine (3.4), which only has two publications to date, offers the same ability to substitute a C=C unit with an isoelectronic B–S unit (Figure 3.1).5-6, 11, 18, 23, 70, 75, 84, 113-121

34 Figure 3.1. Illustration of organic, inorganic, and hybrid inorganic/organic molecules.

1,2-Thiaborine (3.4) was synthesized in 2011 by Ashe and coworkers via 1,2-

118, 122 thiaborolide (3.9). Reacting the tributyl(vinyl)tin (3.5) with BCl3 gave intermediate

3.6, which formed 3.7 by the addition of diisopropylamine (Scheme 3.1). Addition of

propanethiol and trimethylamine gave 1,2-thiaboradiene (3.8) followed by ring closing

metathesis with Grubbs first generation catalyst to produce 1,2-thiaborolide (3.9).

Deprotonation of 3.9 with LDA gave 3.10, and addition of methylene chloride results in the ring expanded 1,2-thiaborine (3.4) in six total steps.

In contrast to this multistep route, the Martin group utilized borole ring insertion chemistry in 2016 to synthesize the B-phenyl substituted 1,2-thiaborine (3.12) (Scheme

75 3.2). Reacting pentaphenylborole (3.11) with elemental sulfur (S8) gave the 1,2- thiaborine insertion product (3.12) in just one step (Scheme 3.2). The aryl group on boron could be varied to a biphenyl substituent, which was utilized to generate a definitive solid- state structure through X-ray diffraction studies. UV/vis spectra of the 1,2-thiaborine

revealed that compound 3.12 is significantly red shifted in relation to benzene, and Nucleus

Independent Chemical Shift (NICS) values showed that these compounds are more

aromatic than the diisopropylamino substituted 1,2-thiaborine (3.4).75 There are only three

1,2-thiaborines compounds reported in literature to date, and their aromatic character, as well as their red-shifted fluorescence make them interesting compounds to study further.

Scheme 3.1. Synthesis of 1,2-thiaborine 3.4 by Ashe.

Scheme 3.2. Synthesis of 1,2-thiaborine 3.12 by Martin.

In order to examine compounds similar to 3.12 with less bulky substituents on the borole backbone, we first had to examine if the 1-phenyl-2,3,4,5-tetramethylborole could undergo the same sort of ring expansion chemistry as pentaphenylborole. Previous work showed that 3.11 reacts with 1,2-dipolar molecules such as benzophenone to produce the

1,2-insertion product (3.13) (Scheme 3.3).8 This work was supported with solid-state

36 structures of the compounds, and we wondered if 1-phenyl-2,3,4,5-tetramethylborole could

do the same type of insertion chemistry observed in pentaphenylborole.

Scheme 3.3. Reaction of pentaphenylborole and benzophenone to give the 1,2-insertion product, 3.13.

3.2 1,2-Dipolar Insertion of Benzophenone into Borole Dimers

Stirring 1-phenyl-2,3,4,5-tetramethylborole (3.14) with benzophenone at room

temperature resulted in no reaction by 1H NMR spectroscopy. The reaction solution was then transferred to a pressure tube and heated outside of the glovebox at 100 ºC, as this temperature had been shown to initiate reactivity in 1-phenyl-2,3,4,5-tetramethylborole in previous studies. After one hour, a 1H NMR spectrum was acquired, revealing the complete consumption of 1-phenyl-2,3,4,5-tetramethylborole dimer, which was later confirmed with

11B{1H} NMR spectroscopy by observance of a new resonance at 44.1 ppm and the absence of 1-phenyl-2,3,4,5-tetramethylborole resonances (-6.5 and 75.0 ppm). This 11B{1H} NMR peak is consistent with a 3-coordinate boron-oxygen bond, indicating the formation of the

1,2-insertion product (3.16) (Scheme 3.4).8, 13, 76, 123-125

Scheme 3.4. Reaction of 1-phenyl-2,3,4,5-tetramethylborole 3.14 with benzophenone.

Single crystals grown for X-ray diffractions studies identified the product as the 7- membered ring 3.16, in which the 1,2-dipolar unit of benzophenone had inserted into the monomeric borole unit (Figure 3.2). The carbon-carbon bond lengths from the original butadiene backbone of borole remain consistent with double bonds [C(1)–C(2) 1.352(11) and C(3)–C(4) 1.367(11) Å]. The B(1)–O(1) bond [1.364(4) Å] is consistent with a B–O single bond (1.37 Å) and the boron center is planar [sum of angles about B(1) = 360.0(10)º],

126 as expected for a 3-coordinate boron. The molecule crystalizes in the Cc space group with two molecules in the asymmetric unit. As was observed in the pentaphenylborole reaction product (3.13), the 1,2-insertion product 3.16 has a boat-like conformation, with

C1 and C5/C4 rising out of the plane defined by B1–O1–C2–C3; the angles between this plane and those defined by O1/C1/C2 and B1/C5/C4/C3 (�prow and �stern) are 50.7(3)º and

38.5(3)º, respectively (Figure 3.2c).

While this reaction proceeds too quickly to observe any intermediate by 1H or

11B{1H} NMR spectroscopy, a possible mechanism is shown in scheme 3.5. The lone pairs on the oxygen atom of the carbonyl coordinates to the Lewis acidic boron center of 3.15 to make the Lewis acid/base adduct 3.17. A resonance structure (3.18) places a cationic charge on the carbon atom of the carbonyl. The B–C bond of 1-phenyl-2,3,4,5-

38 tetramethylborole can break and simultaneously insert the C–O unit of benzophenone to give the 1,2-insertion product 3.16.

a) b)

Figure 3.2. (a) Solid-state structure of 3.16. Hydrogen atoms are omitted for clarity and ellipsoids are depicted at the 50% probability level. Selected bond lengths (Å): B(1)–O(1) 1.364(4), O(1)–C(1) 1.453(4), C(1)–C(2) 1.542(5), C(2)–C(3) 1.349(5), C(3)–C(4) 1.485(5), C(4)–C(5) 1.348(5), C(5)–B(1) 1.564(5); (b) View of the seven-membered ring; (c) Diagram illustrating the �prow and �stern defining the deviation of the ring from planarity into a boat-like confirmation.

Scheme 3.5. Mechanism for the formation of 3.16.

The reaction of benzophenone and 3.14 revealed that 1-phenyl-2,3,4,5- tetramethylborole can undergo 1,2-insertion chemistry in a similar fashion to

39 pentaphenylborole. With these results in hand, we envisioned dimeric boroles may be capable of 1,1-insertion chemistry with elemental sulfur to give 1,2-thiaborine.

3.3 Sulfur Insertion into 1-Phenyl-2,3,4,5-Tetramethylborole Dimer to make 1,2- Thiaborine

Heating an excess of elemental sulfur (S8) with 3.14 at 100 ºC for 24 h resulted in a yellow solution. A 11B{1H} NMR spectrum revealed the disappearance of 3.14 and the presence of two new resonances at 49.8 and 67.1 ppm. 1H NMR spectra of the reaction taken in situ in toluene-d8 revealed that these two products grow with the consumption of

3.14, denoted by the six new peaks observed in the aliphatic region of the spectra (δ 2.24

(s, 3H), 2.22 (s, 3H), 1.99 (s, 3H) and 1.88 (s, 3H) corresponding to one species, denoted by “o”, and δ 2.10 (m, 6H), 1.80 (s, 6H) to the other, denoted by “*”) (Figure 3.3). Allowing the reaction to proceed longer than 24 h did not result in an increase of either product, and heating the reaction at lower temperatures (60 ºC, 70 ºC, and 80 ºC) only increased the amount of other side products.

Once excess sulfur was removed by filtration and reaction with copper metal, the two products were separated using a silica plug, resulting in the isolation of a pale yellow oil with a 11B{1H} NMR spectrum with a singular peak at 49.8 ppm. 1H NMR spectroscopy revealed the isolation of only the aliphatic peaks at δ 2.24, 2.22, 1.99. and 1.88. Despite numerous attempts, isolation of the second product was never successful. The singular peak at 49.8 ppm is consistent with the peak observed for the formation of 1,2-thiaborine compound (3.12) (11B{1H}: 50.8 ppm), and 1H NMR, 13C{1H} NMR spectroscopy, and mass spectrometry (calculated [M+] = 228.1144; found, 228.1143) all supported the successful formation and isolation of the methylated 1,2-thiaborine (3.19) (Scheme 3.6).

40 1 Figure 3.3. Stacked in situ H NMR spectra of the reaction of 3.14 with S8. (“x” denotes 1-phenyl- 2,3,4,5-tetramethylborole dimer, and “o” and “*” denote the newly forming aliphatic peaks)

Scheme 3.6. Formation of 1,2-thiaborine 3.19 by reacting 3.14 with elemental sulfur at 100 ºC.

High quality crystals of compound 3.19 for X-ray diffraction studies could not be grown of the compound to confirm the solid-state structure. Previous metal-borole complexes have been prepared by Ashe and coworkers by introducing a metal carbonyl such as tris(acetonitrile)tricarbonylchromium(0) to 6-membered boron heterocycles, such

41 as 1,2-azaborine.113-114, 127-129 With this in mind, a metal complex was prepared with 1,2- thiaborine (3.19) and chromium.

Addition of the yellow 1,2-thiaborine (3.19) to a solution of excess tris(acetonitrile)tricarbonylchromium(0) in THF at room temperature resulted in an instantaneous color change from yellow to dark red. A 11B{1H} NMR spectrum revealed a shift in the resonance from 49.8 ppm to 28.6 ppm, which is consistent with ƞ6 bound boron complexes 3.20 (22.3 ppm) and 3.21 (19.9 ppm) (Figure 3.4).113, 129 Single crystals grown by vapor diffusion of a solution of the chromium complex in n-pentane into toluene revealed the ƞ6 bound chromium complex (3.22), with the chromium metal center bound to the 1,2-thiaborine ring (Figure 3.5). C–C bond distances of the central BSC4 ring are all between single (1.54 Å) and double (1.34 Å) bond lengths [C(1)–C(2) 1.397(3) Å, C(2)–

C(3) 1.443(3) Å, C(3)–C(4) 1.414(3) Å], indicating a delocalization of electron density about the butadiene unit. The B–S bond length [1.827(2) Å] lies in between the two previously observed 1,2-thiaborine’s 3.4 [1.8552 Å, calculated computationally due to disorder in the solid-state structure of 3.4]75 and 3.12 [1.7934 (17) Å]. The S–C(1) bond length [1.758 (2) Å] relates more closely to the bond lengths observed in the 1,3-thiaborine molybdenum complex (3.20) [1.750 (4) Å and 1.754(3) Å] and is slightly longer than those observed in the non-complexed species 3.4 [1.7277 Å] and 3.12 [1.7325(14) Å], which indicates a lengthening of the S–C bond upon ƞ6 complexation with metal centers. The chromium complex (3.22) shows a deviation from planarity of 0.04 Å, which is similar to the phenyl-substituted 1,2-thiaborine 3.12 (0.05 Å). Interestingly, 3.22 is the first 1,2- thiaborine metal complex ever observed.

42 Figure 3.4. Observed 11B{1H} NMR spectroscopic resonances of known ƞ6 boron containing heteroarene complexes.

Figure 3.5. Solid-state structure of 3.22. Hydrogen atoms are omitted for clarity and ellipsoids are depicted at the 50% probability level. Selected bond lengths (Å): B(1)–S(1) 1.827(2), S(1)–C(1) 1.758(2), C(1)–C(2) 1.397(3), C(2)–C(3) 1.443(3), C(3)–C(4) 1.414(3), C(4)–B(1) 1.517(3).

1,2-Azaborine metal complexes such as 3.21 have been shown to undergo haptotropic migration from the 1,2-azaborine ring to the adjacent phenyl ring by heating the complex (Scheme 3.7).114, 128 Upon heating 3.22 to reflux in THF, no shift in the

11B{1H} NMR spectrum was observed, indicating that a haptotropic migration of the chromium metal to the adjacent phenyl ring on the boron atom of 3.19 had not occurred.

Scheme 3.7. Haptotropic migration of 1,2-azaborine chromium complex 3.21 to form 3.23 upon heating.

3.4 Conclusions

This work describes the first records of a dimeric borole to undergo ring insertion chemistry, with both a 1,2- and a 1,1-insertion reported. This observed reactivity, along with its ability to act as a dienophile in Diels-Alder type cycloaddition reactions (Chapter

Two), proves that the 1-phenyl-2,3,4,5-tetramethylborole dimer can be used to access the monomeric borole species in situ.

The absence of the bulky aryl groups on 1-phenyl-2,3,4,5-tetramethylborole’s carbonaceous backbone allows for novel reactivity as observed in the reaction with 2,3- dimethyl-1,3-butadiene. The reactions with 1,3-cyclohexadiene and benzophenone gave similar products to their pentaphenylborole derivatives, indicating that 1-phenyl-2,3,4,5- tetramethylborole can make less hindered scaffolds through similar reaction conditions.

Finally, the loss of these aryl groups resulted in the synthesis of the first 1,2-thiaborine metal complex with tricarbonylchromium(0).

3.5 Experimental

General Considerations: All manipulations were performed under an inert nitrogen atmosphere using standard Schlenk techniques or in a MBraun Unilab glovebox. Solvents were purchased from commercial sources as anhydrous grade, dried further using a JC

44 Meyer Solvent System with dual columns packed with solvent-appropriate drying agents,

and stored over 4Å molecular sieves. 1-Phenyl-2,3,4,5-tetramethylborole was prepared via

the corresponding literature procedure.48 Benzophenone and elemental sulfur were

purchased from Alfa Aesar and used as received. Cr(CH3CN)3(CO)3 was purchased from

Sigma Aldrich and used as received. CDCl3 and C6D6 for NMR spectroscopy were purchased from Cambridge Isotope Laboratories and dried by stirring for 3 days over CaH2,

distilled, and stored over 4Å molecular sieves. Multinuclear NMR spectra were recorded

on a Bruker 600 MHz or 400 MHz spectrometer. FT-IR spectra were recorded on a Bruker

Alpha ATR FT-IR spectrometer on solid samples. High-resolution mass spectra (HRMS)

were acquired at the University of Texas at Austin Mass Spectrometry Center with CI.

Melting points were measured with a Thomas-Hoover Unimelt capillary melting point

apparatus and are uncorrected. Single-crystal X-ray diffraction data were collected on a

Bruker Apex II-CCD detector using Mo Kα radiation (λ = 0.71073 Å). Crystals were

selected under Paratone oil, mounted on micromounts, and immediately placed in a cold

stream of N2. Structures were solved and refined using SHELXTL and figures produced using OLEX2.

Synthesis of 3.16. Benzophenone (265.3 mg, 1.455 mmol) was added to a solution of 3.14 (297.5 mg, 0.7125 mmol) in toluene (5 mL) and heated at 100 °C for 1 h. Volatiles

were removed in vacuo and the product extracted from excess benzophenone with hexanes.

Volatiles were removed to yield an off-white solid 3.16. Yield: 506.0 mg, 94%. m.p. 35 –

39 ºC. Single crystals for X-ray diffraction were grown from a solution of 3.16 in hexanes

1 left at -35 ºC overnight. H NMR (400 MHz, CDCl3, -40 ºC): d 8.30 (d, J = 8.00 Hz, 1H),

7.98 (d, J = 8.00 Hz, 2H), 7.49 (q, J = 8.00 Hz, 4H), 7.30 (d, J = 8.00 Hz, 1H), 7.25 – 7.08

45 (m, 6H), 6.71 (d, J = 8.00 Hz, 1H), 1.83 (s, 3H), 1.50 (s, 3H), 1.44 (s, 3H), 1.36 (s, 3H).

13 1 C{ H} NMR (100 MHz, CDCl3, ): d 149.86, 148.22, 147.64, 138.08, 137.00, 136.37,

135.57, 130.76, 128.51, 127.86, 126.78, 126.56, 126.50, 126.01, 125.15, 86.28, 20.13,

11 1 -1 18.84, 17.41, 17.01. B{ H} NMR (128 MHz, C6D6): d 44.1. FT-IR (cm (ranked intensity)): 1596 (8), 1490 (14), 1436 (4), 1335 (7), 1274 (2), 1180 (9), 999 (5), 913 (15),

756 (3), 743 (12), 692 (1), 656 (10), 617 (11), 601 (6), 546 (13). High-resolution mass spectrometry (HRMS) electrospray ionization (ESI): calcd for C27H27BO [M]+, 378.2155; found, 378.2168.

Synthesis of 3.19: 3.14 (121.0 mg, 0.309 mmol) was dissolved in toluene (5 mL) and added to elemental sulfur (1.50 g, 5.850 mmol) and heated to 100 ºC for 24 h. Excess elemental sulfur was removed by filtration, and the solvent removed in vacuo to give a yellow oil. The oil was dissolved in hexanes and placed in the freezer overnight to precipitate excess elemental sulfur. Once filtered, the solvent was removed in vacuo, and the yellow oil was dissolved in toluene and added to Cu metal and heated to 100 ºC for 12 h and then filtered to remove excess sulfur. The remaining yellow oil was filtered through a silica gel plug with pentanes. Solvent was removed in vacuo to give 3.19 as a yellow

1 solid. Yield: 68.6 mg, 49%. H NMR (400 MHz, CDCl3): d 7.59 – 7.55 (m, 2H), 7.44 –

13 1 7.35 (m, 3H), 2.55 (s, 3H), 2.34 (s, 3H), 2.29 (s, 6H). C{ H} NMR (150 MHz, CDCl3): d 155.34, 135.92, 133.03, 132.75, 128.07, 127.73, 25.62, 19.86, 19.75, 18.65. 11B{1H}

-1 NMR (128 MHz, CDCl3): d 49.8. FT-IR (cm (ranked intensity)): 2915 (12), 1566 (11),

1429 (7), 1330 (6), 1256 (3), 1208 (13), 1054 (10), 980 (14), 924 (15), 892 (4), 743 (2),

699 (1), 609 (9), 578 (5), 502 (8). High-resolution mass spectrometry (HRMS) chemical ionization (CI): calcd for C14H17BS [M]+, 228.1144; found, 228.1143.

46 Synthesis of 3.22: 3.19 (100 mg, 0.439 mmol, 1.00 eq.) was added to a solution of

Cr(CH3CN)3(CO)3 in THF (5 mL) and stirred for 24 h. Solvent was removed in vacuo to give a red solid. 3.22 was extracted with hexanes (3 x 5 mL) and solvent removed to give

3.22 as a red solid. Single crystals for X-ray diffraction studies were grown from a solution

11 1 of 3.22 in n-pentane into toluene. B{ H} NMR (128 MHz, CDCl3): d 28.6 ppm. FT-IR

(cm-1 (ranked intensity)): 1964 (3), 1908 (6), 1873 (1), 1431 (14), 1376 (9), 1261 (15), 878

(10), 753 (7), 704 (8), 661 (2), 615 (12), 602 (4), 547 (13), 521 (5), 488 (11). High-

resolution mass spectrometry (HRMS) chemical ionization (CI): calcd for C17H17BSCrO3

[M]+, 364.0397; found, 364.0402.

APPENDICES

48 APPENDIX A

Supplementary Information for Chapter Two 3 l C D C

4 7 0 7 0 7 8 0 6 5 3 0 9 8 4 0 6 2 0 7 4 9 8 3 2 9 9 9 5 8 6 2 2 2 0 0 3 3 3 5 8 6 6 6 7 7 1 1 1 1 ...... B Ph 7 7 7 7 7 7 7 7 7 7 7 7 6 6 2 2 2 2 1 1 1 1 1 1 1 Ph Ph Ph Ph 3

* * 5 0 6 2 2 4 0 0 1 6 0 0 9 9 0 1 0 0 0 1 ...... 2 7 1 2 8 4 1 1 5 2

10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 ppm 1 Figure A-1: H NMR Spectrum of 3 in CDCl3 (*n-pentane).

49 3 l C D C

4 7 8 0 6 5 3 6 2 0 9 8 3 2 9 9 2 2 2 0 0 3 3 3 1 1 1 1 ...... 7 7 7 7 7 7 7 7 7 7 7 7 6 6 B Ph Ph Ph Ph Ph 3 5 0 2 2 4 6 0 0 9 0 0 1 ...... 2 7 1 2 8 4

7.70 7.65 7.60 7.55 7.50 7.45 7.40 7.35 7.30 7.25 7.20 7.15 7.10 7.05 7.00 6.95 6.90 6.85 6.80 6.75 6.70 6.65 6.60 6.55 ppm

1 Figure A-2: Expansion of H NMR Spectrum of 3 in CDCl3 (aryl region).

50 0 7 0 7 0 9 8 4 0 7 4 9 5 8 6 5 8 6 6 6 7 7 ...... 2 2 2 2 1 1 1 1 1 1 1

B Ph Ph Ph Ph Ph 3

* * 6 0 0 1 9 1 0 0 . . . . 1 1 5 2

3.1 3.0 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 ppm

1 Figure A-3: Expansion of H NMR Spectrum of 3 in CDCl3 (aliphatic region, *n- pentane).

3 l C D 4 0 1 C 2 5 5 9 3 2 1 1 1 4 8 2 9 0 3 1 4 2

2 9 0 0 6 9 4 9 5 0 2 0 5 2 6 6 2 0 5 5 1 6 6 0 7 4 0 8 6 7 1 . . 6 ...... 3 6 3 8 2 5 . 1 . . . . 8 6 4 3 1 9 8 1 0 0 . 9 8 8 8 7 7 7 6 6 6 6 5 5 . 5 6 4 6 2 7 4 4 4 4 4 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 2 9 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 7 6 5 4 2 2 1 B Ph Ph Ph Ph Ph 3

* *

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 ppm

13 1 Figure A-4: C{ H} NMR Spectrum of 3 in CDCl3 (*n-pentane).

52 4 0 1 2 5 5 9 3 1 2 1 1 4 8 2 9 0 3 1 4 2 2 9 9 5 0 2 0 5 6 6 2 0 5 5 6 6 0 1 4 7 0 8 6 7 1 ...... 8 6 4 3 1 9 8 1 0 0 9 8 8 8 7 7 7 6 6 6 6 5 5 4 4 4 4 4 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

B Ph Ph Ph Ph Ph 3

152 151 150 149 148 147 146 145 144 143 142 141 140 139 138 137 136 135 134 133 132 131 130 129 128 127 126 125 124 ppm

13 1 Figure A-5: Expansion of C{ H} NMR Spectrum of 3 in CDCl3 (aryl region).

B Ph Ph Ph Ph Ph 3

Figure A-6: FT-IR Spectrum of 3.

54 6 D 6 C

8 7 4 6 8 6 5 9 5 2 0 2 5 3 4 6 5 5 2 3 3 2 2 2 0 0 0 5 5 5 6 3 1 1 ...... Ph . . . . .

B 7 7 7 7 7 7 7 7 2 2 2 1 1 1 1 1 0

* 1 9 0 6 0 0 9 2 1 4 0 8 0 0 0 5 9 8 3 0 ...... 2 2 0 1 3 2 3 6 3 2

10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 ppm

1 Figure A-7: H NMR Spectrum of 4 in C6D6 (*dichloromethane).

6 D 6 C

8 6 5 5 3 4 6 5 2 2 2 0 0 0 1 1

Ph ......

B 7 7 7 7 7 7 7 7

4 9 2 1 8 5 3 . . . 2 2 0

7.65 7.60 7.55 7.50 7.45 7.40 7.35 7.30 7.25 7.20 7.15 7.10 7.05 7.00 6.95 6.90 6.85 ppm

1 Figure A-8: Expansion of H NMR Spectrum of 4 in C6D6 (aryl region).

8 7 4 6 9 5 2 0 2 5 2 3 3 5 5 5 6 3 ...... 2 2 2 1 1 1 1 1 0

B Ph

4 1 0 6 0 0 9 4 0 0 0 0 9 8 0 ...... 1 3 2 3 6 3 2

2.6 2.5 2.4 2.3 2.2 2.1 2.0 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 -0.1 ppm

1 Figure A-9: Expansion of H NMR Spectrum of 4 in C6D6 (aliphatic region).

6 D 6 C

0 0 7 7 6 7 4 5 7 4 7 7 9 9 0 2 9 9 4 0 8 8 0 3 7 1 6 8 5 ...... 2 3 8 4 8 7 . . 7 5 0 7 3 0 0 . . . . 8 8 8 6 5 . 5 5 4 4 3 3 3 3 2 2 2 2 2 7 3 3 0 0 1 1 1 1 1 1 1 1 1 1 1 4 4 1 1 1 1 1

B Ph

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 ppm

13 1 Figure A-10: C{ H} NMR Spectrum of 4 in C6D6.

58 6 D 6 C

0 0 7 7 6 7 4 5 7 4 7 9 2 4 9 8 8 0 3 7 1 8 ...... 5 0 7 3 0 0 8 8 8 6 5 4 4 3 3 3 3 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1

B Ph

149 148 147 146 145 144 143 142 141 140 139 138 137 136 135 134 133 132 131 130 129 128 127 126 125 124 123 122 121 120 119 118 ppm

13 1 Figure A-11: Expansion of C{ H} NMR Spectrum of 4 in C6D6 (aryl region).

5 0 . 7 8

B Ph

90 80 70 60 50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 ppm

11 1 Figure A-12: B{ H} NMR Spectrum of 4 in C6D6.

B Ph

Figure A-13: FT-IR Spectrum of 4.

N B Ph

4•pyr 25 ºC

65 ºC

10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 ppm

1 Figure A-14: H NMR Spectra of 4×pyr in C6D6 at 25 ºC and 65 °C.

62 6 D 6 C

0 4 2 1 8 2 0 2 1 4 3 4 1 3 9 2 8 0 8 8 3 1 0 4 8 3 8 7 6 9 9 8 8 8 4 4 4 4 3 3 5 6 4 4 2 2 7 3 1 0 0 0 5 8 6 6 4 1 ...... 8 8 7 7 7 7 6 6 6 6 6 6 6 6 6 2 2 2 2 2 2 2 2 1 1 1 1 1 0

N B Ph

4•pyr 9 1 8 0 7 8 9 3 9 4 5 9 2 1 1 9 9 8 2 0 0 9 9 7 1 8 8 0 0 0 ...... 1 3 0 0 1 0 1 1 1 2 2 3 3 3 3

10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 ppm

1 Figure A-15: H NMR Spectrum of 4×pyr in C6D6 at 65 °C.

6 D 6 C

0 4 2 1 8 2 0 2 4 3 8 8 3 1 6 9 9 8 8 8 4 4 4 3 3 7 0 0 0 1 ...... 8 8 N 7 7 7 7 6 6 6 6 6 6 6 6 6 B Ph

4•pyr 9 1 9 9 2 9 8 7 8 8 . . . . . 1 3 0 0 1

8.7 8.6 8.5 8.4 8.3 8.2 8.1 8.0 7.9 7.8 7.7 7.6 7.5 7.4 7.3 7.2 7.1 7.0 6.9 6.8 6.7 6.6 6.5 6.4 6.3 6.2 6.1 6.0 5.9 ppm

1 Figure A-16: Expansion of H NMR Spectrum of 4×pyr in C6D6 at 65 ºC (aryl region).

64 1 4 1 3 9 2 8 0 0 4 8 3 8 7 4 5 6 4 4 2 2 3 1 5 8 6 6 4 ...... 2 2 2 2 2 2 2 2 1 1 1 1 1 0 N B Ph

4•pyr 8 0 7 8 9 3 4 5 1 1 9 2 0 0 9 9 1 0 0 0 ...... 0 1 1 1 2 2 3 3 3 3

3.3 3.2 3.1 3.0 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 ppm

1 Figure A-17: Expansion of H NMR Spectrum of 4×pyr in C6D6 at 65 ºC (aliphatic region).

6 D 6 C

8 2 7 0 9 6 2 4 8 4 2 9 9 5 7 3 6 1 0 4 7 8 8 7 ...... 4 2 8 0 5 7 . 4 7 7 6 0 0 . . . 8 6 3 . . 9 7 1 4 4 3 3 3 3 2 2 2 3 2 0 1 1 1 1 1 1 1 1 1 4 4 2 1 1 1

N B Ph

4•pyr

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 ppm

13 1 Figure A-18: C{ H} NMR Spectrum of 4×pyr in C6D6 at 65 ºC.

1 2 . 8

N B Ph

4•pyr

90 80 70 60 50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 ppm

11 1 Figure A-19: B{ H} NMR Spectrum of 4×pyr in C6D6.

N B Ph

4•pyr

Figure A-20: FT-IR Spectrum of 4×pyr.

Ph D 6 C

7 6 1 3 1 9 8 7 7 5 9 8 6 6 0 9 8 3 1 4 3 6 0 8 7 6 4 3 8 8 8 9 9 6 6 6 6 6 7 2 2 2 2 2 5 6 3 3 7 7 7 1 1 1 1 1 ...... B 7 7 7 7 7 7 7 7 5 5 5 5 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1

* # 8 5 1 7 0 1 8 0 0 5 9 9 0 9 9 4 2 0 0 1 0 0 0 1 ...... 2 2 0 1 0 1 1 3 6 3 3 1

10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 ppm

1 Figure A-21: H NMR Spectrum of 2 in C6D6 (*hexanes, #grease).

6 D 6 C

7 6 1 9 9 8 3 1 4 8 7 6

Ph 8 8 8 7 2 2 2 2 2 1 1 1 ...... 7 7 7 7 7 7 7 7 5 5 5 5 B

2 5 7 0 1 0 9 9 0 0 0 . . . . . 2 2 0 1 0

7.6 7.5 7.4 7.3 7.2 7.1 7.0 6.9 6.8 6.7 6.6 6.5 6.4 6.3 6.2 6.1 6.0 5.9 5.8 5.7 5.6 5.5 5.4 5.3 ppm

1 Figure A-22: Expansion of H NMR Spectrum of 2 in C6D6 (aryl region).

70 3 9 8 7 7 5 1 8 6 6 0 3 6 0 4 3 9 9 6 6 6 6 6 5 6 3 3 7 7 7 1 1 ...... Ph 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 B

* 8 1 8 0 5 9 9 0 4 2 1 0 0 1 ...... 1 1 3 6 3 3 1

3.1 3.0 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 ppm

1 Figure A-23: Expansion of H NMR Spectrum of 2 in C6D6 (aliphatic region, *hexanes).

Ph D 6 C

7 1 6 9 1 6 6 3 8 1 0 0 4 1 0 4 6 2 . . . . . 4 3 9 7 9 8 5 4 ...... 4 0 B 8 7 7 . . 9 9 3 4 3 3 2 2 2 4 4 2 2 1 1 1 1 1 4 4 2 2 1 1 1 1

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 ppm

13 1 Figure A-24: C{ H} NMR Spectrum of 2 in C6D6.

6 5 Ph . 4 1 - B

90 80 70 60 50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 ppm

11 1 Figure A-25: B{ H} NMR Spectrum of 2 in C6D6.

Ph B

Figure A-26: FT-IR Spectrum of 2.

3 l C D C

3 3 3 1 6 4 4 3 2 8 3 1 6 9 8 1 0 4 9 6 1 7 9 6 1 0 1 9 5 9 7 1 6 6 8 8 6 6 6 6 6 7 7 7 7 6 6 2 2 2 2 3 3 8 6 0 3 3 7 7 7 1 1 1 ...... 8 8 7 7 7 7 7 7 7 7 7 7 7 5 5 5 5 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1

N Ph B

2•pyr 0 0 6 8 0 3 7 6 9 9 7 6 2 4 9 0 0 0 9 3 3 9 0 0 0 7 1 1 ...... 1 0 1 5 1 1 1 1 3 3 2 3 3 1

10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 ppm

1 Figure A-27: H NMR Spectrum of 2×pyr in CDCl3.

3 l C D C

3 3 9 8 1 0 9 6 1 0 1 9 7 6 6 6 6 2 2 2 2 3 3 7 1 1 ...... 8 8 7 7 7 7 7 7 7 7 7 7 7 N Ph B

2•pyr 0 0 6 6 9 0 9 7 . . . . 1 0 1 5

8.8 8.7 8.6 8.5 8.4 8.3 8.2 8.1 8.0 7.9 7.8 7.7 7.6 7.5 7.4 7.3 7.2 7.1 7.0 6.9 6.8 ppm

1 Figure A-28: Expansion of H NMR Spectrum of 2×pyr in CDCl3 (aryl region).

76 3 1 6 4 4 3 2 4 9 7 6 1 9 5 1 8 8 6 6 6 6 6 8 6 0 3 3 7 7 1 ...... 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1

N Ph B

2•pyr 6 8 7 0 3 9 7 4 0 0 9 3 3 0 0 1 ...... 1 1 3 3 2 3 3 1

3.1 3.0 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 ppm

1 Figure A-29: Expansion of H NMR Spectrum of 2×pyr in CDCl3 (aliphatic region).

3 l C D 1 C 8 4 9 0 9 6 0 6 5

9 7 9 4 3 2 8 9 9 8 8 7 7 8 7 9 6 4 6 ...... 9 . . 0 6 4 8 7 6 7 1 . . . . 9 . . 6 3 9 7 7 6 5 3 . . . 4 9 8 3 7 4 4 3 3 2 2 2 2 2 2 2 4 4 2 2 1 1 1 1 1 1 1 1 1 1 7 4 4 2 2 1 1 1 1

N Ph B

2•pyr

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 ppm

13 1 Figure A-30: C{ H} NMR Spectrum of 2×pyr in CDCl3.

1 8 4 9 0 9 6 0 6 5 2 8 9 8 8 7 7 7 6 4 ...... 9 6 3 9 7 7 6 5 3 4 4 3 3 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1

N Ph B

2•pyr

153 152 151 150 149 148 147 146 145 144 143 142 141 140 139 138 137 136 135 134 133 132 131 130 129 128 127 126 125 124 123 122 ppm

13 1 Figure A-31: Expansion of C{ H} NMR Spectrum of 2×pyr in CDCl3 (aryl region).

3 6 . 4 1 -

N Ph B

2•pyr

90 80 70 60 50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 ppm

11 1 Figure A-32: B{ H} NMR Spectrum of 2×pyr in CDCl3.

80 N Ph B

2•pyr

Figure A-33: FT-IR Spectrum of 2×pyr.

3 l C D C

5 3 4 1 2 2 5 4 4 2 0 6 1 7 5 3 3 2 9 5 8 5 1 8 6 8 7 6 2 6 4 1 6 2 9 8 8 0 0 0 9 9 4 4 4 0 0 7 7 7 7 7 1 1 1 2 2 2 2 0 0 9 9 5 5 6 1 1 ......

Ph 7 7 7 7 7 7 7 7 6 6 6 6 6 6 6 6 6 6 6 6 6 3 3 3 3 3 2 2 2 1 1 1 1 1 Ph Ph B

Ph Ph 5

* 4 6 5 3 1 0 0 3 6 6 4 2 7 9 1 . 9 8 9 0 1 0 8 8 0 0 0 0 1 . . . . . 0 ...... 2 2 1 1 3 1 1 1 0 1 1 1 2 1 10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 ppm

1 Figure A-34: H NMR Spectrum of 5 in CDCl3 (*n-pentane).

3 Ph l C D C

5 3 4 1 2 2 7 5 3 2 9 5 8 7 6 2 6 4 6 2 9 8 8 0 0 0 7 7 7 7 1 1 2 2 2 2 0 0 1 1 B Ph ...... Ph 7 7 7 7 7 7 7 7 6 6 6 6 6 6 6 6 6 6 6 6

Ph Ph 5 4 6 5 3 0 0 6 4 7 9 . 9 8 9 1 0 8 8 0 . . . . 0 . . . . 2 2 1 1 3 1 1 1 0 7.6 7.5 7.4 7.3 7.2 7.1 7.0 6.9 6.8 6.7 6.6 6.5 6.4 6.3 6.2 6.1 6.0 5.9 ppm

1 Figure A-35: Expansion of H NMR Spectrum of 5 in CDCl3 (aryl region).

5 4 4 2 0 6 1 8 5 1 8 6 1 9 9 4 4 4 0 0 1 9 9 5 5 6 ...... Ph 3 3 3 3 3 2 2 2 1 1 1 1 1 Ph Ph B

Ph Ph 5

* 1 3 6 2 1 0 0 0 0 1 . . . . . 1 1 1 2 1 4.1 3.9 3.7 3.5 3.3 3.1 2.9 2.7 2.5 2.3 2.1 1.9 1.7 1.5 1.3 1.1 0.9 0.7 0.5 0.3 ppm

1 Figure A-36: Expansion of H NMR Spectrum of 5 in CDCl3 (aliphatic region, *n- pentane).

3 l C D 7 2 C 8 6 1 0 0 7 2 8 3 0 1 8 3 0 5 7 3 6

6 9 8 7 9 8 5 2 6 6 0 5 0 8 2 7 9 5 3 6 6 4 2 3 3 1 . 6 ...... 4 ...... 3 4 7 . 1 . . . 9 9 5 4 3 2 1 1 0 0 9 7 7 7 7 7 7 7 7 5 . 4 6 0 5 3 7 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 7 5 4 2 2 Ph Ph Ph B

Ph Ph 5

* * *

170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 ppm

13 1 Figure A-37: C{ H} NMR Spectrum of 5 in CDCl3 (*n-pentane).

7 2 8 6 1 0 0 7 2 8 3 0 1 8 3 0 5 7 3 6 6 8 5 2 6 6 0 5 0 8 2 7 9 5 3 6 6 4 2 3 3 1 ...... 9 9 5 4 3 2 1 1 0 0 9 7 7 7 7 7 7 7 7 5 4 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Ph Ph Ph B

Ph Ph 5

141 140 139 138 137 136 135 134 133 132 131 130 129 128 127 126 125 124 ppm

13 1 Figure A-38: Expansion of C{ H} NMR Spectrum of 5 in CDCl3 (aryl region).

86 5 8 Ph . 2 - Ph Ph B

Ph Ph 5

90 80 70 60 50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 ppm

11 1 Figure A-39: B{ H} NMR Spectrum of 5 in CDCl3.

Ph Ph Ph B

Ph Ph 5

Figure A-40: FT-IR Spectrum of 5.

88 Table A-1: X-ray crystallographic details for compounds 3, 4×pyr, 2×pyr, and 5.

Compound 3 4×pyr 2×pyr 5 CCDC 1870137 1870138 1870139 1870140 Empirical C40H35B C25H32BN C25H30BN C40H33B Formula FW (g/mol) 526.49 357.32 355.31 524.47 Crystal System Triclinic Triclinic Monoclinic Monoclinic Space Group P-1 P-1 P 21/c C2/c a (Å) 10.6064(7) 7.8497(3) 9.6207(11) 27.0330(7) b (Å) 10.7461(7) 11.0865(5) 13.5919(15) 10.7968(3) c (Å) 13.7129(10) 13.4319(5) 16.5309(17) 23.2970(9) α (deg) 74.9 72.2 90 90.0 β (deg) 89.0 75.1 105.0 121.7 ɣ (deg) 76.6 89.0 90 90.0 V (Å3) 1466.76(17) 1073.09(8) 2087.6(4) 5783.20(3) Z 2 2 4 8 -3 Dc (Mg m ) 1.192 1.106 1.130 1.205 radiation, λ (Å) 0.71073 0.71073 0.71073 0.71073 temp (K) 150 150 150 150 R1[I>2σ]a 0.0510 0.0432 0.0521 0.0455 wR2(F2)a 0.1446 0.1092 0.1621 0.1142 GOF (S)a 1.040 1.040 1.059 1.040 a 2 2 2 2 1/2 R1(F[I > 2(I)]) = ∑ǁ|Fo| - |Fc |ǁ/ ∑ |Fo|; wR2(F [all data]) = [w(Fo - Fc ) ] ; S(all 2 2 2 1/2 2 data) = [w(Fo - Fc ) /(n - p)] (n = no. of data; p = no. of parameters varied; w = 1/[ 2 2 2 2 (Fo ) + (aP) + bP] where P = (Fo + 2Fc )/3 and a and b are constants suggested by the refinement program.

Figure A-41: Solid-state structure of 2×pyr. Hydrogen atoms and disordered atoms on the cyclohexene ring are omitted for clarity and ellipsoids depicted at the 50% probability level.

90 APPENDIX B

Cartesian Coordinates of Optimized Geometries for Chapter Two

All geometries listed have been optimized at the M06-2X/6-31+G(d) level of theory. Coordinates are given in units of Ångstrom, electronic energy (E) in units of Hartrees.

Reactants C -0.04233600 -5.72382600 -0.00168700 H -0.05042900 -6.81047400 -0.00239700 C 0.96922500 -5.03492300 0.66841300 1-Phenyl-2,3,4,5-tetramethylborole H 1.74816100 -5.58296000 1.19073100

E = -568.311767862 C 0.98836000 -3.64300500 0.65161100 0 1 H 1.79378500 -3.11581900 1.15701400 B -0.10730300 0.00001700 0.00001800 C 2.68323500 -0.77773800 0.01699200 C -1.06527200 -1.26241900 0.08315400 C 3.57743700 -0.21197400 0.93837700 C -2.31704800 -0.76070800 0.06519700 C 3.17259400 -1.73628500 -0.88236600 C -2.31705200 0.76073500 -0.06517500 C 4.91832200 -0.58544100 0.95259400 C -1.06526700 1.26244400 -0.08312100 H 3.21114700 0.52705100 1.64658100 C 1.44835100 0.00000800 0.00001200 C 4.51597300 -2.10554600 -0.87374400 C 2.17996500 1.10995600 0.46274400 H 2.48898100 -2.19389100 -1.59367100 H 1.64785100 1.98361000 0.82936200 C 5.39442000 -1.53146700 0.04430400 C 3.57236200 1.10860500 0.47913500 H 5.59377100 -0.13668100 1.67556500 H 4.11432700 1.97183800 0.85496800 H 4.87517800 -2.84582900 -1.58314600 C 4.27033300 -0.00002400 -0.00001900 H 6.44099200 -1.82174400 0.05531000 H 5.35694700 -0.00004000 -0.00002500 C 1.56959000 2.11109400 -0.01839700 C 3.57232500 -1.10863900 -0.47915600 C 1.32860400 3.13377200 0.90908100 H 4.11426600 -1.97188500 -0.85499500 C 2.59479400 2.27929700 -0.95909900 C 2.17992900 -1.10996300 -0.46273700 C 2.10492400 4.29012600 0.90462600 H 1.64779000 -1.98360900 -0.82933000 H 0.53102100 3.02004700 1.63893500 C -0.69528500 -2.71111600 0.23939200 C 3.36070200 3.44118700 -0.97209200 H -0.36229600 -3.14904000 -0.71111400 H 2.78779300 1.48816300 -1.67900100 H 0.13220400 -2.83027900 0.94824400 C 3.12009800 4.44895700 -0.03792700 H -1.52858200 -3.32193400 0.60072800 H 1.91081600 5.07092800 1.63425300 C -3.61801200 -1.49866400 0.16171900 H 4.14876500 3.55847800 -1.71030400 H -3.47187500 -2.57656700 0.25480600 H 3.71988200 5.35445800 -0.04583200 H -4.20205200 -1.15745100 1.02555100 C -1.53885800 2.13351700 0.01896400 H -4.23601800 -1.31976700 -0.72693000 C -1.28206400 3.15222500 -0.90862600 C -3.61803500 1.49865900 -0.16175000 C -2.56265000 2.31689400 0.95844300 H -4.20194200 1.15749300 -1.02569700 C -2.04151200 4.31972700 -0.90546500 H -4.23615400 1.31965200 0.72679300 H -0.48539900 3.02669400 -1.63754400 H -3.47193300 2.57657400 -0.25470900 C -3.31159600 3.48978900 0.97013100 C -0.69522700 2.71113000 -0.23937700 H -2.76791900 1.52891700 1.67840600 H -0.36226500 3.14907200 0.71113100 C -3.05529300 4.49362900 0.03588300 H 0.13231000 2.83023700 -0.94818500 H -1.83527200 5.09737600 -1.63513000 H -1.52847100 3.32196700 -0.60079400 H -4.09873200 3.61881400 1.70737000 H -3.64185100 5.40776300 0.04281900 C -2.69392200 -0.73919100 -0.01535600 Pentaphenylborole C -3.19709200 -1.69061700 0.88397400 E = -1334.99670715 C -3.57962100 -0.16118900 -0.93730800 0 1 C -4.54551600 -2.04097800 0.87481400 B -0.00964400 -1.35878400 0.00087000 H -2.52019900 -2.15772800 1.59553900 C 1.25501600 -0.39974800 -0.00630700 C -4.92561600 -0.51583500 -0.95210500 C 0.77073300 0.86610900 -0.00598100 H -3.20261700 0.57240100 -1.64554800 C -0.75813400 0.87709000 0.00758400 C -5.41538400 -1.45483400 -0.04381100 C -1.26044200 -0.38169300 0.00829700 H -4.91541200 -2.77602100 1.58417100 C -0.02121900 -2.90745800 0.00007100 H -5.59434000 -0.05790100 -1.67557700 C -1.04171500 -3.62698400 -0.65237800 H -6.46592100 -1.73041800 -0.05530700 H -1.83906200 -3.08710300 -1.15721600 C -1.04346000 -5.01900700 -0.67092200 H -1.83049600 -5.55466500 -1.19392300

91 2,3-Dimethyl-1,3-butadiene Dimer E = -234.502724615 E = -1136.6961089 0 1 0 1 C 0.74426200 -0.12775400 -0.02500400 C -0.11007200 1.82347600 0.01638800 C -0.74425500 -0.12772800 0.02508800 C 1.93907700 1.22341500 -1.42064800 C 1.44157700 1.13017500 0.43176600 C 1.32652000 0.08951700 -1.94089500 H 1.20855700 1.97316100 -0.22931900 C 2.70437300 -1.01765100 0.43091100 H 1.11989500 1.41256900 1.44121900 C 0.28360700 -0.41282000 -1.00845900 H 2.52611100 0.99528200 0.43786900 C 1.41951800 1.53660000 -0.05604100 C -1.44161600 1.13014900 -0.43177600 C 4.08562100 -0.83241600 0.26016900 H -1.20881400 1.97316400 0.22935100 H 4.44540900 0.00700100 -0.33219000 H -1.11978300 1.41259500 -1.44116400 C 2.29436900 -2.11283200 1.20901400 H -2.52614000 0.99516600 -0.43808800 H 1.23005300 -2.27978100 1.36626400 C 1.42522900 -1.18831500 -0.47411100 B 1.61862400 -0.05793200 -0.17571000 C -1.42518700 -1.18836100 0.47407800 C 4.58235400 -2.77930900 1.60005500 H 0.91475800 -2.07102600 -0.84799000 H 5.30408800 -3.45629500 2.04850700 H 2.51193800 -1.19437200 -0.49217300 C 5.01595000 -1.69902800 0.83259300 H -0.91468700 -2.07101700 0.84804300 H 6.07897600 -1.53111700 0.68114600 H -2.51189900 -1.19452300 0.49200800 C 3.21598800 -2.98319800 1.78915200 H 2.86854700 -3.82060200 2.38837500 C 2.35886400 2.35467900 0.81347800 1,3-Cyclohexadiene H 3.39916300 2.06072800 0.64423800 E = -233.304725077 H 2.28263900 3.43532700 0.63127500 0 1 H 2.16596400 2.17370800 1.87258300 C -1.28109900 -0.73575200 0.00011400 C 3.15247100 1.84676600 -2.06339600 C -0.13654400 -1.42672900 0.00014000 H 3.92323900 1.10911800 -2.30990300 C 1.22448600 -0.77570100 -0.00030400 H 2.84956000 2.32585400 -3.00235600 C 1.22397100 0.77665400 0.00043200 H 3.59761700 2.61735600 -1.43237200 C -0.13778700 1.42666400 -0.00013500 C 1.85979200 -0.67990000 -3.11634700 C -1.28148400 0.73469500 -0.00026900 H 2.59790300 -1.42506800 -2.79037200 H -2.23567100 -1.25476500 0.00035600 H 1.05484200 -1.21037200 -3.63241800 H -0.15525600 -2.51472300 0.00037500 H 2.34847200 -0.01517400 -3.83415300 H 1.77983600 -1.14857500 0.86955000 C -0.13289700 -1.85209500 -1.24690200 H 1.77793900 1.14915800 0.87132400 H -0.70278200 -1.97248600 -2.17813000 H -0.15757500 2.51460700 -0.00032500 H 0.74142300 -2.50916800 -1.31186000 H -2.23643900 1.25318800 -0.00060400 H -0.75690400 -2.22422200 -0.42632200 H 1.77903100 1.14991800 -0.86942700 C -0.83203900 0.64875200 -0.75132500 H 1.77887900 -1.14779500 -0.87111300 C -0.60437700 1.70247700 1.45677400 C -1.48430000 0.69465800 1.68947700 B -1.90386100 0.13409900 0.31745800 Pyridine C -2.02337900 0.40312500 3.06715200 E =-248.180065105 H -1.21270300 0.33278100 3.80248800 0 1 H -2.70097600 1.19404400 3.42002100 C -1.19656100 0.67170700 0.00000400 H -2.57851900 -0.53871600 3.09098800 C -1.13957500 -0.72149400 -0.00009000 C -0.21484500 2.67514700 2.54046900 C 1.13993000 -0.72095900 -0.00001300 H 0.34092000 3.53816800 2.17080900 C 1.19626500 0.67219900 -0.00002200 H -1.11455200 3.04170400 3.04972500 C -0.00032900 1.38330200 0.00002500 H 0.39722000 2.18061600 3.30600800 H -2.15584300 1.17923800 0.00006500 C -1.47574500 1.05218600 -2.08708900 H -2.05446300 -1.30985800 0.00008700 H -0.75261000 1.52148300 -2.76563700 H 2.05503400 -1.30897800 0.00001900 H -1.87556700 0.16770800 -2.59529200 H 2.15528300 1.18023300 -0.00002600 H -2.31494300 1.74443500 -1.95487500 H -0.00051400 2.46957400 0.00003300 C -0.42466700 3.22114900 -0.53637700 N 0.00030300 -1.41696200 0.00005700 H -1.50015600 3.42984700 -0.51678700 H 0.07266600 3.99983700 0.05121200 H -0.07411800 3.31605500 -1.56957500 Dimerization C -3.28318300 -0.57365300 0.04671000 C -3.53904800 -1.46759500 -1.00896700 Dimerization of 1-phenyl-2,3,4,5-tetramethylborole C -4.37569300 -0.24152200 0.87093600 C -4.80083400 -2.01989700 -1.21551600 H -2.73611300 -1.74888000 -1.68185800 Ph C -5.64871500 -0.76758800 0.65867800 B H -4.23176300 0.46191500 1.68699600 C -5.86231700 -1.66876700 -0.38227000 Ph H -4.95889300 -2.71777400 -2.03318000 B H -6.47066400 -0.47931000 1.30821800 H -6.84962700 -2.09159400 -0.54666800

92 TS for Dimer Reaction of 1-phenyl-2,3,4,5- E = -1136.62468174 Hartree 0 1 tetramethylborole C -0.15855600 -1.63261200 1.49734400 with 2,3-dimethyl-1,3-butadiene C -0.86874200 -2.16392800 -1.18893200 C 0.03120600 -1.30560300 -1.80900000 C -2.27435500 1.09027800 -0.39697000 C 0.18919100 -0.07237600 -1.09604400 C -1.40774100 -1.58127000 0.01600900 Ph C -3.62876400 0.81591100 -0.13529500 H -3.91884200 -0.15908000 0.23897900 B C -1.98997700 2.38239800 -0.87901900 H -0.96343700 2.66181100 -1.08827500 B -1.11885300 0.01917700 -0.14573700

C -4.31698100 3.02686500 -0.82204900 TS1 H -5.09639400 3.76574700 -0.98620900 E=-802.800672912 Hartree C -4.63567800 1.75966400 -0.34223100 0 1 H -5.66941100 1.50096700 -0.12858600 C -0.67523800 -0.29898700 0.89962700 C -2.98375900 3.33553700 -1.08846000 C -1.27882100 -1.53250500 0.94977000 H -2.71619500 4.32081900 -1.46080700 C -0.98163900 -2.34961600 -0.25802000 C -2.66620900 -2.24501300 0.54260500 C 1.79240600 0.04848300 -0.06147200 H -3.44824600 -2.18946300 -0.22462100 C 2.30611400 1.34653700 0.08184800 H -2.51290600 -3.30868300 0.75632700 H 1.65397800 2.19989200 -0.10203100 H -3.05749500 -1.77571900 1.44758900 C 3.62937300 1.58504100 0.45324600 C -1.26051900 -3.53774000 -1.65677000 H 3.99087100 2.60573300 0.55237000 H -0.70457300 -3.85425600 -2.54132200 C 4.48869700 0.51429300 0.69557900 H -1.08647900 -4.28358100 -0.87053100 H 5.52192700 0.69259200 0.98048900 H -2.32928300 -3.58296800 -1.90142300 C 4.00661000 -0.78773500 0.56593200 C 0.77713900 -1.58990500 -3.08229700 H 4.66543200 -1.63201400 0.75389500 H 1.85894300 -1.50176100 -2.92503600 C 2.68105000 -1.00973000 0.19277000 H 0.57508700 -2.58706700 -3.47749300 H 2.32119900 -2.03422100 0.10574600 H 0.51200500 -0.86022100 -3.85671600 C -0.10454700 -1.70524300 -1.06599900 C 0.82330200 1.07502500 -1.85975100 B 0.24841900 -0.24717600 -0.40122000 H 1.77341200 0.79364100 -2.32360400 C -0.61421900 0.69054800 2.01841400 H 0.14118000 1.38900200 -2.66332900 H -0.56231000 1.71240800 1.61711900 H 1.02978600 1.94354600 -1.22965300 H -1.46390300 0.64364400 2.71040000 C 1.12531500 -1.48680400 0.89770500 H 0.31028200 0.54825100 2.59320900 C -0.64125400 -0.25167600 1.90114900 C -2.08068000 -2.10407700 2.08008300 C 0.17692400 0.72257300 1.38084800 H -3.02887500 -2.52196800 1.71881500 B 1.39368800 -0.01627100 0.62474000 H -1.53717900 -2.93089000 2.55585000 C -0.03346100 2.18223300 1.67533600 H -2.29874900 -1.35907600 2.84892000 H -1.09070200 2.45323200 1.76030300 C -1.62032900 -3.69979900 -0.44457900 H 0.45283600 2.42674700 2.63027800 H -1.27409700 -4.18531100 -1.35992800 H 0.42320000 2.82129300 0.91298100 H -1.39066900 -4.37041300 0.39297400 C -1.79605200 0.01474800 2.82909800 H -2.71424800 -3.62674900 -0.50126900 H -2.13669100 -0.89197600 3.33389400 C 0.47356700 -2.22085500 -2.34832000 H -1.48947300 0.72998200 3.60031000 H 1.55577700 -2.37180100 -2.23279400 H -2.65126900 0.45820400 2.30346500 H 0.03523900 -3.16407400 -2.69064200 C 1.86978900 -2.67943300 0.41898800 H 0.36215700 -1.48430400 -3.15472300 H 1.39459900 -3.05432000 -0.50908600 C -0.37073300 0.98479400 -1.57542800 H 2.91416800 -2.45011200 0.19214000 C -1.13752700 2.03601700 -0.99361900 H 1.84445700 -3.50839600 1.13613200 H -0.98877600 0.25882300 -2.11511300 C -0.46773400 -2.85773200 2.33565400 C -2.77047300 0.45839200 -0.21528400 H 0.23689500 -2.92283900 3.17279500 C -2.34716600 1.76690900 -0.29790800 H -1.47580100 -2.84449100 2.75391900 H -2.46839400 -0.29879000 -0.93064300 H -0.37009000 -3.77369800 1.74407400 H -3.61740700 0.19966600 0.41781600 C 2.81102400 0.61297200 0.31016900 H 0.46638500 1.32583000 -2.18588200 C 3.67578600 0.07578200 -0.65940900 C -0.61792400 3.44593500 -1.00288300 C 3.29259300 1.70776800 1.04500100 H 0.30207300 3.53319800 -1.58305700 C 4.94624100 0.59841700 -0.88843400 H -1.36838200 4.12274900 -1.43012100 H 3.33808000 -0.76666900 -1.26118100 H -0.42432600 3.80326900 0.01693700 C 4.56495400 2.23990300 0.82935100 C -3.04375000 2.85552100 0.48544100 H 2.66548300 2.15074900 1.81525300 H -3.90773300 2.45064500 1.01868100 C 5.39713600 1.68735300 -0.14130100 H -2.38335800 3.32165700 1.22644700 H 5.58545800 0.15904900 -1.64997000 H -3.40763700 3.65358700 -0.17255900 H 4.90553800 3.08621900 1.42028300 H 6.38705300 2.09975600 -0.31566600

93 Ph Ph B B

Int2 TS2 E=-802.836472756 Hartree E= -802.836438932 Hartree 0 1 0 1 C -0.00665500 -1.46988300 0.23123900 C -1.27529500 1.73537900 -0.58315800 C -1.43057200 -1.56464600 0.65451800 C -2.18533300 1.17846600 0.29193400 C -2.29799400 -1.02367700 -0.28478900 C -0.41330700 -1.20583700 0.06858300 C 1.31405900 -0.27697500 -1.69622700 C -0.96250700 -1.28697100 -1.21584000 C 2.48765000 -0.38217500 -0.72050800 H -1.27588400 -0.37876400 -1.72951400 C -0.25409600 1.25382300 -0.08194400 C -1.13365600 -2.50551000 -1.87203700 C -0.83963000 1.43041500 1.17749700 H -1.53872600 -2.52480700 -2.88043400 H -1.25826600 0.57367100 1.70553900 C -0.80903600 -3.69620300 -1.22480900 C -0.91734400 2.67773800 1.79634000 H -0.95492900 -4.65014200 -1.72357500 H -1.35956800 2.76484300 2.78551500 C -0.31258500 -3.64833400 0.07696200 C -0.44645100 3.81183900 1.13737800 H -0.06474200 -4.56835600 0.59997400 H -0.51469400 4.78917000 1.60675400 C -0.12753200 -2.42126800 0.71195200 C 0.09987100 3.67542400 -0.13714400 H 0.27177800 -2.41548000 1.72262300 H 0.46468300 4.54995300 -0.66990500 C -1.50369600 0.36942100 1.26771300 C 0.18642600 2.41746000 -0.73385700 B 0.00063700 0.24663200 0.86523200 H 0.62902300 2.34523000 -1.72370300 C -1.59322300 2.52298300 -1.81157100 C 1.10524700 -1.25148700 1.24584900 H -1.14013000 3.52010600 -1.74019100 C 2.39084100 -0.78281100 0.56575900 H -1.13260400 2.04211000 -2.68412600 H 0.82287700 -0.49584900 1.99447100 H -2.66239600 2.63583300 -2.00073400 H 1.49634400 0.58902900 -2.34718400 C -3.68439000 1.27748700 0.21513500 C -1.55670500 -0.32148800 -1.27976900 H -4.01331700 2.07571700 -0.45391200 B -0.04455700 -0.23727300 -0.84186700 H -4.11903000 0.33565200 -0.14509800 C 3.80475500 0.01563300 -1.34885200 H -4.11834100 1.47674700 1.20116800 H 3.84806900 1.10465600 -1.48850100 C -2.26716300 -0.31876200 2.34639100 H 4.68574500 -0.29143200 -0.78246200 H -3.14247000 -0.85736800 1.96314200 H 3.88035100 -0.43010600 -2.34837900 H -1.63937000 -1.00727800 2.91538100 C 3.56822100 -0.83423500 1.51470300 H -2.64587200 0.45089500 3.03510900 H 3.96830600 -1.85434100 1.59839900 C 0.55489200 2.76531600 0.63527900 H 4.38660400 -0.17125300 1.23020100 H 1.60131000 2.68066500 0.94236400 H 3.24631300 -0.53976800 2.52103700 H 0.46359300 3.66958100 0.01758300 C 0.28155100 -2.80288100 -0.52200400 H -0.06250400 2.89643600 1.53041200 H 1.33177500 -2.82813400 -0.82535200 C 0.13975800 1.49512000 -0.16106900 H 0.10371200 -3.67187600 0.12711300 C 1.36381300 0.09204100 1.69304100 H -0.34424400 -2.90483000 -1.41448100 C 1.21931600 1.21120600 -1.19716800 C -1.82387900 -2.21679900 1.93774000 C 2.53223600 0.12648900 0.70719100 H -1.53608200 -3.27648200 1.91004200 H 1.45919800 -0.82144000 2.29537300 H -1.25786700 -1.77039900 2.76436100 H 1.49710000 0.91346700 2.41697600 H -2.89026000 -2.14782300 2.16067300 C 2.46106300 0.59259400 -0.55815800 C -3.80169800 -1.05974700 -0.23372200 H 0.85837600 0.51936300 -1.97334900 H -4.17400600 -1.83003400 0.44567900 H 1.53057200 2.12650700 -1.73241200 H -4.20748800 -0.09427100 0.09527300 C 3.62818500 0.57593500 -1.52079700 H -4.22168200 -1.26696500 -1.22388600 H 4.11632700 1.55918300 -1.57059700 C -2.24210000 0.34823000 -2.41817700 H 4.38737500 -0.16760200 -1.27377900 H -1.56481900 1.00287800 -2.97062900 H 3.27046500 0.35175700 -2.53319300 H -2.60701700 -0.42950600 -3.10586000 C 3.81033800 -0.42216200 1.30128500 H -3.12131200 0.92049600 -2.09705200 H 4.71117500 -0.17888300 0.73526300 H 1.35160400 -1.14306800 -2.37817800 H 3.93912000 -0.02643700 2.31636000 H 1.33570900 -2.16996700 1.81565900 H 3.74947500 -1.51496000 1.39785200

94 B Ph B Ph

Int3 TS3

E = -802.883809686 E= -802.838392178 Hartree 0 1 0 1 C 1.40136400 1.12877000 0.12063500 C 0.24010700 2.10709700 -0.59538700 C 0.44073200 2.18794500 -0.40407500 C -0.98844500 1.90800600 -0.03832900 C -0.83625100 1.98714200 -0.02466900 C -1.94351600 -0.38887900 0.10576100 C 0.97804100 -1.24196600 1.33176800 C -1.70010100 -0.69260700 -1.24386100 C 2.15717300 -1.72905800 0.49746900 H -0.91893300 -0.15627800 -1.77771100 C -1.95645100 -0.27925500 0.14819000 C -2.42935300 -1.67026800 -1.91194500 C -1.78398100 -0.54471900 -1.21992600 H -2.21434900 -1.88009800 -2.95626600 H -1.04429700 0.02544300 -1.77921800 C -3.42937900 -2.38130900 -1.24673300 C -2.55057400 -1.50452700 -1.87416800 H -3.99996500 -3.14584000 -1.76572300 H -2.39448300 -1.68691300 -2.93384500 C -3.68235800 -2.09648400 0.09062200 C -3.51716200 -2.22681400 -1.17444400 H -4.45504000 -2.64055900 0.62720500 H -4.11916300 -2.97475700 -1.68192300 C -2.94993300 -1.11082200 0.75697000 C -3.70317800 -1.97399600 0.18189700 H -3.17247500 -0.91669000 1.80107500 H -4.45576800 -2.52476400 0.73964700 C -1.08713800 0.65289900 0.82523500 C -2.93075700 -1.01269200 0.83568600 B 0.47072000 0.12427800 0.82123600 H -3.09991200 -0.83700200 1.89343800 C 0.69654900 3.25354600 -1.45366100 C 2.14410100 0.33565200 -0.97276500 H 1.50619800 3.80701900 -0.96191300 C 2.66396800 -1.02828300 -0.53490600 H 1.08936100 2.89906300 -2.41409200 H 1.48831800 0.19041400 -1.84688000 H -0.10813300 3.96112200 -1.66476200 H 0.20452300 -2.02356200 1.37667600 C -2.17775100 2.80678300 -0.16885800 C -1.04316000 0.73075400 0.83065700 H -3.07826600 2.20724300 -0.34794700 B 0.42918600 0.13153000 0.84040800 H -2.34309500 3.36019700 0.76461900 C 2.66546200 -3.07782900 0.94400400 H -2.07552000 3.53363900 -0.97754700 H 2.88600600 -3.05252300 2.01886400 C -1.65452300 1.01745300 2.20477800 H 1.89013000 -3.84208400 0.80331600 H -2.71546100 1.29668000 2.16806800 H 3.56724000 -3.41059600 0.42914300 H -1.55242000 0.17509100 2.89902300 C 3.79190600 -1.50651500 -1.41723100 H -1.10243400 1.86007700 2.63406400 H 4.70056900 -0.91790100 -1.23426700 C 1.45221200 1.12062400 1.90784000 H 4.03855400 -2.56094500 -1.29184300 H 1.01355400 0.73034500 2.83516400 H 3.52736300 -1.35217600 -2.47107800 H 2.51113300 0.85677200 1.88852500 C 2.42984300 1.71438300 1.10910500 H 1.32534800 2.20497900 1.89753400 H 3.06629100 0.92249100 1.52044600 C 1.11182300 1.00795000 -0.21453300 H 3.08447200 2.43744400 0.60464600 C 1.01821600 -1.37247700 0.91464100 H 1.94106700 2.23323000 1.94234000 C 2.45810000 0.74457400 -0.77798500 C 0.97225300 3.32173100 -1.23348300 C 2.41401400 -1.53984300 0.32509900 H 0.18362800 3.96539900 -1.62981700 H 0.34304200 -2.06288800 0.38319400 H 1.65210500 3.95130700 -0.64564300 H 1.04349200 -1.74996300 1.95021700 H 1.55191500 2.93787500 -2.08277100 C 3.05394100 -0.60646100 -0.40828800 C -2.02887200 2.84460800 -0.33574600 H 2.36848600 0.81272900 -1.87683900 H -2.83263900 2.23827500 -0.77174200 H 3.16304900 1.55481800 -0.52101900 H -2.43171800 3.29674400 0.57966100 C 4.44052400 -0.75371200 -0.98755100 H -1.79866100 3.65498000 -1.03122000 H 5.09893100 0.03619600 -0.60143900 C -1.49904700 1.09097600 2.25682800 H 4.91455600 -1.70997800 -0.77006300 H -2.52927200 1.46928700 2.26658600 H 4.41708500 -0.63283400 -2.07909200 H -1.45349800 0.22696300 2.92942900 C 3.01473200 -2.88573500 0.65932700 H -0.85217200 1.87140000 2.67222300 H 3.93799500 -3.12160000 0.12935600 H 1.31403300 -1.11943100 2.37914500 H 3.21674100 -2.94756700 1.73658100 H 2.99697400 0.92590400 -1.34629200 H 2.28719800 -3.67507000 0.43476400

95 B Ph B Ph

Int4 TS4 E= -802.845037957 Hartree E= -802.844681987 Hartree 0 1 0 1 C 0.85558500 1.95889600 -0.41855400 C 0.84055200 1.93775000 -0.41587700 C -0.51228400 1.86099800 -0.27592900 C -0.51711400 1.88794100 -0.25731500 C -2.09550300 -0.05104100 0.15465500 C -2.09225500 -0.04566100 0.16046200 C -2.25081700 -0.27740300 -1.22272100 C -2.27048800 -0.22688800 -1.22049900 H -1.57040800 0.20162700 -1.92452100 H -1.62990900 0.30808000 -1.91866200 C -3.25027700 -1.10937900 -1.72012800 C -3.24585100 -1.08301800 -1.72653500 H -3.34062400 -1.25772400 -2.79285700 H -3.35571600 -1.19448500 -2.80193900 C -4.12732600 -1.75196700 -0.84796500 C -4.07466900 -1.79382700 -0.86094300 H -4.90767500 -2.40268700 -1.23127200 H -4.83664700 -2.46183300 -1.25142300 C -3.98629900 -1.54738300 0.52235900 C -3.90980000 -1.63449000 0.51313100 H -4.65835200 -2.04199600 1.21843900 H -4.54390700 -2.18285100 1.20453500 C -2.98840800 -0.70694800 1.01437900 C -2.93594600 -0.77209100 1.01412700 H -2.90479600 -0.57082100 2.08798900 H -2.83021900 -0.67411500 2.09013400 C -0.96013600 0.79356700 0.68874100 C -0.97813900 0.82005000 0.71005300 B 0.45577100 -0.03956500 0.97936600 B 0.42046200 -0.00237800 1.02754800 C 1.58364000 2.95713200 -1.27901600 C 1.59418100 2.89575100 -1.29811400 H 2.28783400 3.55320000 -0.68790100 H 2.29908100 3.50513300 -0.72070200 H 2.16222400 2.45168500 -2.06082500 H 2.17630800 2.35688300 -2.05524200 H 0.89416300 3.64917400 -1.76909400 H 0.91803800 3.57820700 -1.81946700 C -1.48477600 2.77445900 -0.96074800 C -1.48307600 2.82596600 -0.92341200 H -2.51775800 2.49563800 -0.74262100 H -2.51785200 2.55096700 -0.70588500 H -1.31957000 3.80557200 -0.62213100 H -1.31544400 3.85029700 -0.56678200 H -1.34819800 2.77150000 -2.04855400 H -1.35647900 2.84113600 -2.01225900 C -1.36201000 1.54472600 1.98571800 C -1.40469300 1.55770700 2.00408600 H -2.26551300 2.15287200 1.84449300 H -2.30280000 2.16977100 1.84808200 H -1.54824000 0.83982400 2.79977400 H -1.61125800 0.85046700 2.81159000 H -0.54636600 2.19906500 2.31015200 H -0.59387400 2.20926100 2.34722000 C 0.70415200 -0.67579800 2.44451600 C 0.62153800 -0.78679300 2.41386500 H -0.10489900 -1.37462200 2.70348300 H -0.18574200 -1.51535100 2.57731800 H 1.63967700 -1.25002200 2.48259300 H 1.56584000 -1.34652300 2.43679400 H 0.75093100 0.07305100 3.24646400 H 0.62501900 -0.11201500 3.28013100 C 1.48237400 0.94735200 0.36262800 C 1.46494700 0.91588500 0.39017600 C 0.75915800 -1.22036600 -0.20053900 C 0.79889300 -1.08824100 -0.30021900 C 2.93894300 0.68620300 0.38898200 C 2.93345700 0.67508700 0.42355000 C 2.21338100 -1.59417800 -0.37064700 C 2.22792000 -1.54379300 -0.42337500 H 0.34285700 -0.94851700 -1.18074900 H 0.41689000 -0.73892400 -1.26683600 H 0.18379500 -2.09681700 0.13667300 H 0.15064700 -1.92433600 0.00524800 C 3.21592500 -0.73417300 -0.11971100 C 3.24176600 -0.72626000 -0.09744900 H 3.52493300 1.40569200 -0.20080700 H 3.50001300 1.41261300 -0.16285600 H 3.29663600 0.75160700 1.42939600 H 3.29038300 0.74802200 1.46296400 C 4.68869500 -0.99841700 -0.28447800 C 4.71198800 -1.02570400 -0.18679100 H 5.21998900 -0.77482200 0.64984100 H 5.19044100 -0.87622600 0.78969000 H 4.91498000 -2.02968300 -0.55686400 H 4.92378600 -2.04554800 -0.51062700 H 5.11744400 -0.34456000 -1.05512300 H 5.20456600 -0.34034900 -0.88846200 C 2.42185800 -3.00756200 -0.85825600 C 2.39171100 -2.95236300 -0.93577400 H 3.45655900 -3.24970400 -1.10576200 H 3.42983900 -3.24099200 -1.10902200 H 2.07694300 -3.71775500 -0.09636600 H 1.95389800 -3.66198200 -0.22269500 H 1.80934000 -3.18525600 -1.75039400 H 1.84326800 -3.07546600 -1.87746200

96 B Ph N B Ph

Compound 4 E = -802.886948897 Compound 4pyr 0 1 E= -1051.10320323 Hartree C -0.49124800 1.69075300 0.66071000 0 1 C 0.74197200 1.83227600 0.14069500 C 1.27927800 -0.85555400 1.15039700 C 2.24963200 -0.16016800 -0.24272300 C 0.11788700 -1.53384500 1.09592100 C 2.23134300 -0.50019700 1.12013000 C -2.11146400 -1.15877800 -0.09834700 H 1.45931200 -0.07737200 1.76020300 C -2.66802800 -0.61337200 1.07120700 C 3.18916600 -1.34992200 1.66699800 H -2.02751700 -0.45746800 1.93701800 H 3.15123800 -1.59186500 2.72564300 C -4.01164200 -0.25384500 1.14901200 C 4.19498800 -1.88470800 0.86287000 H -4.40073000 0.16896200 2.07220500 H 4.94515700 -2.54559200 1.28697200 C -4.85619400 -0.43962400 0.05501300 C 4.22809800 -1.55733100 -0.49034900 H -5.90554600 -0.16524800 0.11390900 H 5.00826500 -1.96247000 -1.12905500 C -4.33253200 -0.99625800 -1.11001400 C 3.26602400 -0.70759400 -1.03659400 H -4.97495000 -1.15945200 -1.97164600 H 3.31829200 -0.46857500 -2.09421600 C -2.98516000 -1.34983600 -1.18237800 C 1.13714200 0.71140700 -0.81729300 H -2.60845900 -1.77182100 -2.10935200 B -0.16252300 -0.21328000 -0.79734400 C -0.62299700 -1.39586600 -0.23175700 C -1.14527400 2.60310500 1.66244300 B 0.16970500 -0.07999600 -0.91956400 H -1.06904900 2.19225000 2.67756400 C 2.28314600 -0.95618000 2.26594300 H -0.69893900 3.60043200 1.67556500 H 2.63802800 0.03304200 2.58243100 H -2.21459200 2.71845400 1.45061300 H 1.87950500 -1.47111700 3.14256700 C 1.73079000 2.92638700 0.42024000 H 3.17415700 -1.50580100 1.93212400 H 2.68406700 2.49861400 0.75640100 C -0.34429900 -2.53212700 2.13444200 H 1.94461400 3.50256600 -0.48907900 H -1.36374500 -2.87245700 1.92846500 H 1.38564900 3.62388800 1.18702000 H 0.30246500 -3.41889900 2.14416700 C 1.45247700 1.24056900 -2.22514900 H -0.33501800 -2.11490600 3.14834900 H 2.41036500 1.77613400 -2.25266000 C -0.33746200 -2.67031800 -1.05722300 H 1.50028600 0.43263100 -2.96384500 H -0.78069400 -3.55752400 -0.58490200 H 0.66900700 1.93593000 -2.54603800 H -0.72669100 -2.60576000 -2.07792200 C -0.35132200 -1.55279800 -1.58882600 H 0.74204100 -2.83361400 -1.13649100 H -0.51893200 -2.37831600 -0.88220400 C 0.19472100 -0.05722100 -2.53814400 H -1.25804700 -1.51461200 -2.20812800 H 0.59365700 0.88260300 -2.94969900 H 0.49913100 -1.82376300 -2.22382800 H 0.83452400 -0.85900300 -2.92050000 C -1.23196100 0.46286300 0.15569200 H -0.78397600 -0.23086900 -3.00936400 C -1.78413300 -0.49683700 1.24316100 C 1.62048900 -0.09684300 -0.13134500 C -2.48725800 0.79095600 -0.71047600 C 2.32624600 1.27274600 0.11465900 C -3.05102700 -1.05894800 0.63701800 C 2.74564700 -0.91757900 -0.85321100 H -2.01823700 0.03437200 2.18011800 C 3.80615200 1.02167200 -0.04837300 H -1.06787400 -1.28730900 1.51293800 H 2.12381200 1.69871800 1.10901700 C -3.43731100 -0.35167000 -0.43350400 H 1.98960700 2.03555500 -0.60806900 H -2.94188200 1.75287300 -0.42452400 C 4.03649500 -0.18792400 -0.57172500 H -2.25084100 0.88392800 -1.78288100 H 2.78253200 -1.95696400 -0.49382400 C -4.64720000 -0.54212300 -1.29507200 H 2.59429200 -0.97834000 -1.93965700 H -4.35375200 -0.73422600 -2.33519100 C 5.34636900 -0.82434400 -0.92068700 H -5.27350300 -1.37340900 -0.96185100 H 5.37739700 -1.08665200 -1.98589900 H -5.26399300 0.36547900 -1.30330400 H 6.20066800 -0.17658000 -0.70653200 C -3.72274900 -2.23652700 1.27240000 H 5.48100200 -1.75964700 -0.36190200 H -4.65068700 -2.51535700 0.76686700 C 4.79148500 2.08193300 0.33637600 H -3.05691500 -3.10889200 1.26600400 H 5.82523800 1.78816300 0.13578400 H -3.95840900 -2.02636600 2.32339700 H 4.59244600 3.01325300 -0.20950500 H 4.70871500 2.31852200 1.40545000 C -1.66969700 1.73981700 -1.20434000 C -0.60164900 1.72628300 0.83756100 C -2.55732900 2.71778300 -0.78038500 H -1.73361900 1.32022300 -2.19831400 C -1.43557800 2.72134200 1.32597100 H 0.14832300 1.26447000 1.46329900 C -2.43857200 3.22724400 0.50746200 H -3.32915500 3.06089200 -1.45990100 H -1.30176500 3.07011600 2.34392400 H -3.11755400 3.99429500 0.86710900

97 N -0.69991000 1.24535100 -0.41439100

Ph Reaction of 1-phenyl-2,3,4,5- tetramethylborole with 1,3-cyclohexadiene B

Ph B TS6 to form Compound 2 E = -801.609611916 Hartree 0 1 C 0.57363100 -1.78892400 -0.14245100 Compound 2 C 2.51671300 0.29929100 -0.71059200 E = -801.687825645 Hartree C 2.51543500 0.88730700 0.60717200 0 1 C -1.21261600 0.84653000 -0.16667600 C -2.06805600 -0.51989100 -0.77836500 C 1.24283200 0.95561600 1.12576900 C -0.02152400 -1.91713600 -0.02278200 C 1.25706900 -0.10623500 -1.13190800 C -0.03167500 -1.37183900 1.26058100 C -1.55699600 1.34067300 -1.43639200 C 1.74484800 0.49363200 -0.15028600 H -0.83757300 1.27272500 -2.24754100 C -0.72195300 -0.06136000 1.25880900 C -2.16645700 1.02148100 0.85161200 C -0.61527500 -0.97978800 -1.01613200 H -1.94151900 0.68409600 1.85925700 C 2.83447900 -0.19210000 -0.71201300 B 0.24888400 0.28047000 0.10561100 H 2.70761600 -1.21995100 -1.04651900 C -3.72032600 2.08499500 -0.66180100 C 1.96284200 1.82032500 0.25602800 H -4.68195400 2.55408400 -0.85109400 H 1.13700500 2.38380200 0.68589500 C -2.78829100 1.94774900 -1.68736300 B 0.31950000 -0.14592100 0.01604300 H -3.01516600 2.31857500 -2.68360000 C 4.27284700 1.72917000 -0.44267100 C -3.39950400 1.62518500 0.61517500 H 5.24389600 2.20322000 -0.55494000 H -4.11019400 1.74042200 1.42949800 C 4.08273900 0.41129800 -0.85678100 C 1.03730500 -0.48423900 -2.58069300 H 4.90702200 -0.14579900 -1.29416700 H 1.38668000 0.31918700 -3.24091800 C 3.20644400 2.43441000 0.11307600 H 1.58948600 -1.39247600 -2.86458400 H 3.34318300 3.46350100 0.43446100 H -0.01345400 -0.65919100 -2.81745000 C -0.21691600 -1.19297400 -2.46458300 C 3.77809100 0.20134900 -1.52323300 H 0.83546800 -1.47450900 -2.56199400 H 3.65475100 -0.44338400 -2.39694700 H -0.82516800 -1.97029800 -2.94770800 H 4.09501000 1.19004100 -1.88171700 H -0.33961700 -0.26936900 -3.03600100 H 4.60616900 -0.19480000 -0.92289300 C 0.78448100 -3.14741600 -0.35613600 C 3.79639400 1.33600600 1.25818100 H 0.30581700 -4.02268700 0.09870300 H 3.61699700 1.86284000 2.19765300 H 0.83272900 -3.32314300 -1.43187300 H 4.45161600 0.48282800 1.47739600 H 1.80574700 -3.09488600 0.03542600 H 4.35942100 2.00843600 0.60014500 C 0.81209900 -1.88857300 2.39249400 C 0.86840100 1.48954900 2.47799000 H 1.81274500 -1.43646200 2.36702900 H 0.56887000 0.68482100 3.16449800 H 0.35979200 -1.64631900 3.35792600 H 1.68553500 2.03419400 2.96050800 H 0.93291100 -2.97359500 2.33227100 H 0.01188800 2.16942300 2.39785500 C -0.49731500 0.80732400 2.47921700 C -0.60116700 -2.34498300 -0.92983400 H -1.06179700 0.44414800 3.35003400 C 0.28365600 -1.32183900 1.16871100 H 0.56184900 0.83900900 2.75526900 C -0.99799800 -1.71047400 1.79484600 H -0.81825300 1.83593500 2.28693300 C -1.77857700 -2.65524500 1.25754700 C -2.37994300 0.70750600 -1.64430300 C -1.42714500 -3.30091800 -0.05791600 C -2.17902600 -0.20316000 0.73053100 H -1.24582900 -1.27269500 2.75916500 C -3.08144900 0.95497900 1.06631500 H -0.88458900 -4.24067400 0.12646200 C -3.81502800 1.62366700 0.17436500 H -2.33659900 -3.57393700 -0.60379100 C -3.72483500 1.34280100 -1.29912600 H -0.25245800 -2.84636700 -1.83627700 H -3.17841900 1.19788300 2.12386000 H -1.26230500 -1.52515700 -1.23274500 H -4.54677100 0.67785700 -1.60450300 H 1.54096400 -2.24201800 -0.33292500 H -3.85769200 2.27052100 -1.86799300 H 1.11818500 -1.28086900 1.86213400 H -2.36766700 0.43149900 -2.70384700 H -2.67104300 -2.98970400 1.78099400 H -1.58463600 1.45228500 -1.49065500 H -2.77352100 -1.32163100 -1.04855600 H -2.61682400 -1.07660000 1.23975900 H -4.49961700 2.39993000 0.51154500

98 Reaction of pentaphenylborole with 2,3- C -2.39461300 1.03937100 0.01760500 C -2.72551600 2.23739100 0.66253700 dimethyl-1,3-butadiene C -3.38128700 0.36791100 -0.71421500 C -4.01141700 2.76121400 0.56556700 H -1.96225200 2.75906100 1.23624200 C -4.66717400 0.89482300 -0.81595200 H -3.13585600 -0.57189300 -1.20491000 Ph C -4.98545000 2.09272500 -0.17746400 B H -4.25460700 3.69152300 1.07080700 Ph H -5.42228600 0.36557700 -1.38996700 Ph H -5.98913100 2.50087100 -0.25267900 C 0.23670700 2.53595400 -0.70873700 Ph Ph C -0.65587900 3.00825300 -1.68547000 Int1 C 1.28049200 3.37802700 -0.29357700 E= -1569.56230855 Hartree C -0.51466900 4.28421900 -2.22018900 0 1 H -1.46468700 2.37030700 -2.03127800 C 1.36955100 0.33125200 0.09606400 C 1.40831400 4.66215000 -0.81624400 C 0.13730700 1.16543300 -0.16506300 H 1.98166800 3.02905200 0.45887100 C -1.02299500 0.48212100 0.11165500 C 0.51350600 5.11924900 -1.78197400 C 1.86349000 -2.17079800 0.73785100 H -1.21045300 4.62780500 -2.98004000 C 3.11236600 -1.99959100 -0.12529300 H 2.21322500 5.30418700 -0.47060500 C 0.09140900 -1.69637000 -1.36782300 H 0.61860000 6.11823100 -2.19509700 C -0.35615100 -0.88422700 -2.41653500 H -0.58994000 0.16119700 -2.24130900 C -0.50572100 -1.37406500 -3.71524000 H -0.83791000 -0.70482000 -4.50395500 Ph C -0.25212100 -2.71336100 -3.99072800 B H -0.38067000 -3.10242900 -4.99668400 Ph C 0.16359300 -3.55275800 -2.95657500 Ph H 0.37760900 -4.59958400 -3.15447700 C 0.32061100 -3.05382700 -1.66764000 Ph Ph H 0.67175300 -3.72918100 -0.89547600 TS C 2.45139800 0.31243100 -0.98161600 E = -1569.51004445 Hartree C 3.35388000 -0.91663200 -0.89428900 0 1 H 1.97688400 0.32158700 -1.97352300 C 1.36955100 0.33125200 0.09606400 H 1.59881000 -3.23461900 0.78318400 C 0.13730700 1.16543300 -0.16506300 C -0.74630500 -0.92159600 0.44059200 C -1.02299500 0.48212100 0.11165500 B 0.75241200 -1.17229000 0.19509700 C 1.86349000 -2.17079800 0.73785100 C 4.05965000 -3.17132400 -0.02084300 C 3.11236600 -1.99959100 -0.12529300 H 3.62294100 -4.05968500 -0.49829900 C 0.09140900 -1.69637000 -1.36782300 H 5.04366400 -2.99901900 -0.45929800 C -0.35615100 -0.88422700 -2.41653500 H 4.20512600 -3.42583200 1.03643000 H -0.58994000 0.16119700 -2.24130900 C 4.57506000 -0.75648100 -1.77011000 C -0.50572100 -1.37406500 -3.71524000 H 5.10138800 -1.69054400 -1.96898400 H -0.83791000 -0.70482000 -4.50395500 H 4.28298200 -0.33087000 -2.73822400 C -0.25212100 -2.71336100 -3.99072800 H 5.29096000 -0.05140000 -1.32342100 H -0.38067000 -3.10242900 -4.99668400 H 2.11820900 -1.90472400 1.77649400 C 0.16359300 -3.55275800 -2.95657500 H 3.08221600 1.21615700 -0.96215300 H 0.37760900 -4.59958400 -3.15447700 C 1.92748100 0.69799000 1.48619200 C 0.32061100 -3.05382700 -1.66764000 C 3.29887800 0.88564300 1.70714000 H 0.67175300 -3.72918100 -0.89547600 C 1.07737200 0.82465000 2.59580700 C 2.45139800 0.31243100 -0.98161600 C 3.79576600 1.18808800 2.97559300 C 3.35388000 -0.91663200 -0.89428900 H 4.00335800 0.78058300 0.88957400 H 1.97688400 0.32158700 -1.97352300 C 1.56950100 1.12593500 3.86284400 H 1.59881000 -3.23461900 0.78318400 H 0.00718700 0.68592200 2.47450500 C -0.74630500 -0.92159600 0.44059200 C 2.93612200 1.31239200 4.06279700 B 0.75241200 -1.17229000 0.19509700 H 4.86596100 1.32267000 3.10789300 C 4.05965000 -3.17132400 -0.02084300 H 0.87818200 1.21471600 4.69647000 H 3.62294100 -4.05968500 -0.49829900 H 3.32311900 1.54810300 5.04973300 H 5.04366400 -2.99901900 -0.45929800 C -1.78994500 -1.78478600 1.03296600 H 4.20512600 -3.42583200 1.03643000 C -2.01475200 -3.12192700 0.68191200 C 4.57506000 -0.75648100 -1.77011000 C -2.53217100 -1.24447000 2.09882700 H 5.10138800 -1.69054400 -1.96898400 C -2.94805400 -3.89162600 1.37188700 H 4.28298200 -0.33087000 -2.73822400 H -1.48335300 -3.55464700 -0.15653800 H 5.29096000 -0.05140000 -1.32342100 C -3.44485000 -2.02341000 2.80204100 H 2.11820900 -1.90472400 1.77649400 H -2.38416700 -0.20744600 2.38673400 H 3.08221600 1.21615700 -0.96215300 C -3.66226200 -3.35125800 2.43883800 C 1.92748100 0.69799000 1.48619200 H -3.11579100 -4.92132600 1.06953300 C 3.29887800 0.88564300 1.70714000 H -3.99574000 -1.58446900 3.62870300 C 1.07737200 0.82465000 2.59580700 H -4.38578700 -3.95590900 2.97743300

99 C 3.79576600 1.18808800 2.97559300 H -1.46356300 -1.12944700 3.16263100 H 4.00335800 0.78058300 0.88957400 C 1.35605800 2.57176100 -1.17406600 C 1.56950100 1.12593500 3.86284400 C 0.65523000 3.83851700 -0.69874400 H 0.00718700 0.68592200 2.47450500 H 2.42805000 2.61527100 -0.92773600 C 2.93612200 1.31239200 4.06279700 H -1.65051100 2.56799300 1.17985700 H 4.86596100 1.32267000 3.10789300 C -0.71136000 -0.14569200 0.71152000 H 0.87818200 1.21471600 4.69647000 B -0.81877100 1.22000900 -0.44944400 H 3.32311900 1.54810300 5.04973300 C -1.21736100 5.11193600 0.38678000 C -1.78994500 -1.78478600 1.03296600 H -2.12933300 5.31397800 -0.18930900 C -2.01475200 -3.12192700 0.68191200 H -1.53166400 4.96844400 1.42796800 C -2.53217100 -1.24447000 2.09882700 H -0.58708900 6.00114300 0.34924800 C -2.94805400 -3.89162600 1.37188700 C 1.50643600 5.05415400 -0.97548500 H -1.48335300 -3.55464700 -0.15653800 H 1.85439800 5.03717500 -2.01663500 C -3.44485000 -2.02341000 2.80204100 H 0.98673800 5.99925500 -0.82064300 H -2.38416700 -0.20744600 2.38673400 H 2.40626500 5.05354500 -0.34571300 C -3.66226200 -3.35125800 2.43883800 H -2.39501000 2.84683700 -0.36524100 H -3.11579100 -4.92132600 1.06953300 H 1.31651700 2.54710000 -2.27997200 H -3.99574000 -1.58446900 3.62870300 C -2.01308600 -0.91163100 0.66758200 H -4.38578700 -3.95590900 2.97743300 C -3.13117400 -0.38052800 1.33037400 C -2.39461300 1.03937100 0.01760500 C -2.22942700 -2.00369600 -0.18391900 C -2.72551600 2.23739100 0.66253700 C -4.39946500 -0.93351000 1.17735500 C -3.38128700 0.36791100 -0.71421500 H -3.00867300 0.49574200 1.96249400 C -4.01141700 2.76121400 0.56556700 C -3.49658500 -2.56109700 -0.33861300 H -1.96225200 2.75906100 1.23624200 H -1.41402600 -2.40862100 -0.77423600 C -4.66717400 0.89482300 -0.81595200 C -4.59003800 -2.03508000 0.34493500 H -3.13585600 -0.57189300 -1.20491000 H -5.24196700 -0.49306500 1.70365700 C -4.98545000 2.09272500 -0.17746400 H -3.62800100 -3.39920600 -1.01728000 H -4.25460700 3.69152300 1.07080700 H -5.57880800 -2.46636800 0.21853800 H -5.42228600 0.36557700 -1.38996700 C 0.83648700 -2.22500000 0.27788700 H -5.98913100 2.50087100 -0.25267900 C 1.48346600 -2.87682400 -0.78522200 C 0.23670700 2.53595400 -0.70873700 C 0.47003600 -2.96895300 1.40884400 C -0.65587900 3.00825300 -1.68547000 C 1.75057900 -4.23916000 -0.71930200 C 1.28049200 3.37802700 -0.29357700 H 1.75214200 -2.31371900 -1.67438800 C -0.51466900 4.28421900 -2.22018900 C 0.76567700 -4.32535900 1.48570600 H -1.46468700 2.37030700 -2.03127800 H -0.03462600 -2.47567400 2.23145900 C 1.40831400 4.66215000 -0.81624400 C 1.39985700 -4.96438700 0.42015900 H 1.98166800 3.02905200 0.45887100 H 2.23485000 -4.73502000 -1.55497200 C 0.51350600 5.11924900 -1.78197400 H 0.48978800 -4.88742000 2.37268900 H -1.21045300 4.62780500 -2.98004000 H 1.61679900 -6.02720800 0.47557200 H 2.21322500 5.30418700 -0.47060500 C 2.85111100 -0.10994200 -0.66024600 H 0.61860000 6.11823100 -2.19509700 C 3.66513500 -0.59250400 0.37212700 C 3.42896400 0.16855500 -1.90399200 C 5.02552600 -0.79925100 0.16198400 H 3.22207400 -0.80288200 1.34322800 C 4.78987300 -0.04214900 -2.11696000 H 2.80385700 0.53905500 -2.71389800 Ph C 5.59078200 -0.52768500 -1.08422900 B H 5.64569900 -1.17204000 0.97188900 Ph H 5.22380900 0.17175200 -3.08938200 Ph H 6.65167400 -0.69148700 -1.24881100 Ph Ph C -1.57136900 0.61683300 -1.77166500 C -2.96564900 0.73420200 -1.89255100 Compound 3 C -0.91840400 -0.10893500 -2.78124300 E=-1569.51675646 Hartree C -3.67260400 0.13917100 -2.93517000 0 1 H -3.52577800 1.27116200 -1.13071100 C 0.72623300 1.31883100 -0.69990200 C -1.61279000 -0.70208600 -3.83800400 C 1.40530600 0.12573500 -0.42100700 H 0.16273300 -0.23476200 -2.75032100 C 0.52417200 -0.79086100 0.18117800 C -2.99805700 -0.58694100 -3.91636100 C -1.42581600 2.61912000 0.10175500 H -4.75485200 0.23404200 -2.97444600 C -0.55719800 3.84807600 -0.11382000 H -1.06715200 -1.25302800 -4.60044800 C -0.34582300 0.39537200 2.12175200 H -3.54480400 -1.05228500 -4.73191200 C 0.47972500 1.50734900 2.32655400

H 0.85316100 2.08085800 1.48313900

C 0.83027300 1.93411300 3.60553500 H 1.46495500 2.80885200 3.71574300 C 0.36598800 1.25593200 4.72984000 H 0.63682800 1.58894500 5.72731700 C -0.45762200 0.14847500 4.55045900 H -0.83928600 -0.39631900 5.40958500 C -0.80330800 -0.27396800 3.26788500

100 H 3.22207400 -0.80288200 1.34322800 C 4.78987300 -0.04214900 -2.11696000 Ph H 2.80385700 0.53905500 -2.71389800 Ph C 5.59078200 -0.52768500 -1.08422900 B H 5.64569900 -1.17204000 0.97188900 Ph H 5.22380900 0.17175200 -3.08938200 H 6.65167400 -0.69148700 -1.24881100 Ph Ph C -1.57136900 0.61683300 -1.77166500 C -2.96564900 0.73420200 -1.89255100 Int5 C -0.91840400 -0.10893500 -2.78124300 E= -1569.51675646 Hartree C -3.67260400 0.13917100 -2.93517000 0 1 H -3.52577800 1.27116200 -1.13071100 C 0.72623300 1.31883100 -0.69990200 C -1.61279000 -0.70208600 -3.83800400 C 1.40530600 0.12573500 -0.42100700 H 0.16273300 -0.23476200 -2.75032100 C 0.52417200 -0.79086100 0.18117800 C -2.99805700 -0.58694100 -3.91636100 C -1.42581600 2.61912000 0.10175500 H -4.75485200 0.23404200 -2.97444600 C -0.55719800 3.84807600 -0.11382000 H -1.06715200 -1.25302800 -4.60044800 C -0.34582300 0.39537200 2.12175200 H -3.54480400 -1.05228500 -4.73191200 C 0.47972500 1.50734900 2.32655400

H 0.85316100 2.08085800 1.48313900 C 0.83027300 1.93411300 3.60553500 Ph H 1.46495500 2.80885200 3.71574300 B Ph C 0.36598800 1.25593200 4.72984000 H 0.63682800 1.58894500 5.72731700 Ph C -0.45762200 0.14847500 4.55045900 H -0.83928600 -0.39631900 5.40958500 Ph Ph C -0.80330800 -0.27396800 3.26788500 Int6 H -1.46356300 -1.12944700 3.16263100 E= -1569.56161828 Hartree C 1.35605800 2.57176100 -1.17406600 0 1 C 0.65523000 3.83851700 -0.69874400 C -1.28047500 0.10244800 -0.28595300 H 2.42805000 2.61527100 -0.92773600 C -0.36782700 1.08199400 -0.11120200 H -1.65051100 2.56799300 1.17985700 C 1.39462000 0.41209500 1.61712000 C -0.71136000 -0.14569200 0.71152000 C 0.45000700 0.67171600 2.61891300 B -0.81877100 1.22000900 -0.44944400 H -0.53069600 1.04885300 2.34370400 C -1.21736100 5.11193600 0.38678000 C 0.74869600 0.47226400 3.96617100 H -2.12933300 5.31397800 -0.18930900 H -0.00389500 0.69216000 4.71823800 H -1.53166400 4.96844400 1.42796800 C 2.00101600 -0.00231800 4.34653500 H -0.58708900 6.00114300 0.34924800 H 2.23448100 -0.15984400 5.39538800 C 1.50643600 5.05415400 -0.97548500 C 2.95077900 -0.27691500 3.36324600 H 1.85439800 5.03717500 -2.01663500 H 3.93050400 -0.65579500 3.63998500 H 0.98673800 5.99925500 -0.82064300 C 2.64790500 -0.07916300 2.01942800 H 2.40626500 5.05354500 -0.34571300 H 3.39712200 -0.31363800 1.26890800 H -2.39501000 2.84683700 -0.36524100 C 1.05439000 0.54541500 0.12156400 H 1.31651700 2.54710000 -2.27997200 B 0.86638000 -1.00646500 -0.25152800 C -2.01308600 -0.91163100 0.66758200 C -0.68939800 -1.30766700 -0.25679900 C -3.13117400 -0.38052800 1.33037400 C -1.18115600 -2.05526800 1.03194600 C -2.22942700 -2.00369600 -0.18391900 C -1.20160700 -2.20027700 -1.42401500 C -4.39946500 -0.93351000 1.17735500 C -2.21466100 -3.03825600 0.53589300 H -3.00867300 0.49574200 1.96249400 H -1.60758300 -1.34812300 1.75725400 C -3.49658500 -2.56109700 -0.33861300 H -0.36674900 -2.56682600 1.56793800 H -1.41402600 -2.40862100 -0.77423600 C -2.23588100 -3.10789800 -0.80171900 C -4.59003800 -2.03508000 0.34493500 H -1.61848200 -1.60167900 -2.24316100 H -5.24196700 -0.49306500 1.70365700 H -0.39290500 -2.79154700 -1.87672600 H -3.62800100 -3.39920600 -1.01728000 C -3.11257500 -3.94286100 -1.68180600 H -5.57880800 -2.46636800 0.21853800 H -2.50923400 -4.56247600 -2.35708800 C 0.83648700 -2.22500000 0.27788700 H -3.77298500 -4.60246500 -1.11333400 C 1.48346600 -2.87682400 -0.78522200 H -3.73909300 -3.29877900 -2.31272300 C 0.47003600 -2.96895300 1.40884400 C -3.06068000 -3.77771600 1.52569700 C 1.75057900 -4.23916000 -0.71930200 H -3.73069800 -4.49759300 1.04896100 H 1.75214200 -2.31371900 -1.67438800 H -2.43444600 -4.31953600 2.24547600 C 0.76567700 -4.32535900 1.48570600 H -3.67393500 -3.07318900 2.10187300 H -0.03462600 -2.47567400 2.23145900 C 2.06524700 1.30534300 -0.72601200 C 1.39985700 -4.96438700 0.42015900 C 3.11924300 2.06437400 -0.21332000 H 2.23485000 -4.73502000 -1.55497200 C 1.90197100 1.26099700 -2.11800800 H 0.48978800 -4.88742000 2.37268900 C 3.99921500 2.73494700 -1.06490800 H 1.61679900 -6.02720800 0.47557200 H 3.26144200 2.13877700 0.86113300 C 2.85111100 -0.10994200 -0.66024600 C 2.77586700 1.92592700 -2.97101200 C 3.66513500 -0.59250400 0.37212700 H 1.07075800 0.69248500 -2.53487600 C 3.42896400 0.16855500 -1.90399200 C 3.83737600 2.66421200 -2.44575300 C 5.02552600 -0.79925100 0.16198400 H 4.81190500 3.31867800 -0.64139800

101 H 2.62941600 1.86814000 -4.04588200 H 0.32956600 -2.40682700 4.74885600 H 4.52438200 3.18412600 -3.10686600 C -0.81985900 -3.34838900 -1.07325200 C -0.64351000 2.54020400 -0.10238900 C 0.83533800 -1.58530800 -1.87879400 C 0.08757100 3.40707100 0.72402700 C 1.72225500 -2.77993900 -2.12170600 C -1.61095700 3.10113900 -0.94998600 C 1.27958500 -4.03608100 -2.21006000 C -0.16540100 4.77653500 0.73105400 C -0.15622300 -4.40236300 -1.95457100 H 0.86131200 3.00889800 1.37314700 H 2.77667000 -2.57025100 -2.29132000 C -1.86289100 4.46979900 -0.94603800 H -0.69863200 -4.49673200 -2.90718700 H -2.16252400 2.45895600 -1.62885200 H -0.21306100 -5.38593900 -1.47399000 C -1.14551400 5.31456900 -0.10032800 H -1.88583700 -3.56365500 -0.94418500 H 0.41123300 5.42437900 1.38520000 H -0.35935600 -3.38347200 -0.07448000 H -2.61693300 4.87755500 -1.61333200 H -1.21181300 -1.85785500 -2.57427400 H -1.34025200 6.38314000 -0.09828100 H 0.90976400 -0.95960300 -2.78243700 C -2.75972900 0.28392300 -0.30973100 H 1.97799900 -4.83238100 -2.46069900 C -3.42457600 0.60677700 0.88029000 C 2.73848000 -0.72670600 -0.34814500 C -3.52787400 0.10929500 -1.46900500 C 3.66853100 -0.10641600 -1.19322900 C -4.81173400 0.73492500 0.91822800 C 3.21307000 -1.44386100 0.75153700 H -2.84207700 0.77039400 1.78372500 C 5.03398700 -0.18870400 -0.93833100 C -4.91410500 0.23969600 -1.43513100 H 3.31242800 0.45772800 -2.05354400 H -3.03690100 -0.09891900 -2.41533900 C 4.58147700 -1.52610400 1.01437300 C -5.56290600 0.54609900 -0.23952100 H 2.50432200 -1.93895400 1.40860000 H -5.30354600 0.98899300 1.85296700 C 5.49529000 -0.89764100 0.17218600 H -5.48830900 0.10853500 -2.34815400 H 5.73853700 0.30401200 -1.60249300 H -6.64393000 0.64723600 -0.21398600 H 4.93071800 -2.08443200 1.87839500 C 1.97555700 -2.07230000 -0.53486700 H 6.56036300 -0.96030600 0.37618200 C 3.27859400 -1.74714100 -0.95792900 C -2.60492100 -1.11686200 -0.21704600 C 1.67781100 -3.43866400 -0.36336400 C -3.60948400 -0.89205900 -1.16762900 C 4.23422600 -2.73281200 -1.19278100 C -2.97957500 -1.55547100 1.05463100 H 3.54955100 -0.70700000 -1.11878600 C -4.95107500 -1.08706500 -0.85443000 C 2.63342300 -4.42878700 -0.57666500 H -3.33286000 -0.54063400 -2.15992200 H 0.67880800 -3.73738900 -0.05125300 C -4.32441300 -1.75330000 1.37341500 C 3.91558800 -4.07594700 -0.99565900 H -2.21654500 -1.73627500 1.80551700 H 5.22884100 -2.45231800 -1.52779500 C -5.31372400 -1.51806600 0.42251300 H 2.37728500 -5.47327700 -0.42331600 H -5.71453900 -0.89689300 -1.60355700 H 4.66236600 -4.84524100 -1.17237700 H -4.59525700 -2.09103600 2.36993000 H -6.36017600 -1.66835600 0.67192000 C -1.73635300 1.63885300 -0.69055200 C -2.41206600 1.94662000 0.49388000 Reaction of pentaphenylborole and 1,3- C -2.06963200 2.32875300 -1.86040500 C -3.37637200 2.95167300 0.51209000 cyclohexadiene H -2.20044800 1.38279500 1.39751800 C -3.03567900 3.33208600 -1.84263500 H -1.58206700 2.06202200 -2.79528500 Ph C -3.68760300 3.65066500 -0.65282100 H -3.89296900 3.18006800 1.43970300 Ph Ph B H -3.28209900 3.85959800 -2.75962000 H -4.44231900 4.43138700 -0.63614600 C 1.34488500 1.96157200 -0.59759100 C 1.21443900 2.94470400 -1.58398400 Ph Ph C 2.20232400 2.20114500 0.48448200 C 1.90813600 4.14947300 -1.48481500 Compound 5 H 0.57639800 2.76103600 -2.44233800 E = -1568.35930142 Hartree C 2.88830500 3.40771600 0.58678300 0 1 H 2.33804400 1.43801900 1.24544500 C -0.64258800 -1.93458300 -1.63558100 C 2.74344400 4.38670300 -0.39594600 C -0.75765800 0.51842900 -0.77961400 H 1.79410700 4.90024700 -2.26130600 C 0.63279100 0.66376200 -0.75325100 H 3.54504200 3.57807700 1.43481700 C 0.11183100 -0.40470200 1.97925000 H 3.28365800 5.32549700 -0.31583100 C 1.27524000 -0.68197400 -0.67645900 C -1.16616600 -0.90919800 -0.60839900 C 0.06498200 0.82793700 2.64669200 H -0.00351700 1.74844000 2.07082700 C 0.20945100 -1.56041900 2.77422600 H 0.24415100 -2.53660300 2.29092200 B 0.06475700 -0.57529100 0.41157800 C 0.20429000 -0.25451900 4.80378300 H 0.23921400 -0.19594000 5.88795100 C 0.10935300 0.90609700 4.03972100 H 0.07072700 1.87719400 4.52588700 C 0.25524100 -1.49370800 4.16439500

102 Model compounds for reaction of pentaphenyl C 1.11307100 -1.87538800 2.59159700 borole and 1,3-cyclohexadiene H 2.17649900 -2.06408200 2.39673800 H 1.06852600 -1.10296200 3.37026400

H 0.67433300 -2.78905200 2.99896300 C -1.37262900 -3.19552400 1.11979900 H -2.44585900 -2.97936900 1.19188900 H -1.25722700 -3.98660300 0.36788500 H -1.04123300 -3.59697700 2.08006000 C -0.89428200 -2.08772400 -1.81279300 H -1.62653000 -2.90489400 -1.83833000 H -1.01685200 -1.49807500 -2.72817600 Model borole H 0.10711300 -2.52969400 -1.83830000 0 1 C 0.95974000 -0.15028400 0.64842500 B -0.82035900 0.63756500 0.01844900 C -0.05325400 1.33426200 -1.37066900 C 1.08970600 1.99874300 0.03445000 C 0.88372200 1.11673200 1.52551600 C -0.15057000 2.88253600 -0.00403800 C 0.19217800 2.53854800 -0.46600700 C -1.28651100 2.15426200 0.02239900 H -0.97745800 1.48952200 -1.94534500 C 2.45417600 2.61394100 0.10321600 H 0.75979500 1.28860500 -2.11702000 H 3.21293100 1.87237000 0.36372600 C 0.60143900 2.43154300 0.81242700 H 2.73491600 3.06409300 -0.85832600 H 0.09366500 0.97601200 2.27991700 H 2.48106400 3.41840400 0.84721300 H 1.81437400 1.22900800 2.10557600 C 0.00124900 4.37242900 -0.06222100 C 0.83876500 3.60784100 1.72973900 H -0.95600300 4.87539700 -0.21265700 H 1.91412900 3.75209100 1.90273200 H 0.43627900 4.75716300 0.86896900 H 0.42612800 4.54734800 1.36219000 H 0.67678200 4.66960600 -0.87334200 H 0.39002100 3.41083200 2.71140200 C -2.68687800 2.69563600 -0.03566600 C -0.07419200 3.84727000 -1.16766200 H -2.72073000 3.74762700 -0.33552500 H 0.21093300 4.73028900 -0.59500200 H -3.29733300 2.12752400 -0.74687400 H 0.47532800 3.87222500 -2.11719900 H -3.18693900 2.62169600 0.93913400 H -1.13896500 3.93156900 -1.42016200 C 0.76689300 0.68553200 0.03787500 C 2.33643200 -0.35893300 0.02288600 C 1.72922900 -0.43187800 0.08978800 C 2.72681000 -1.63074400 -0.42283400 C 1.56706900 -1.46649000 1.02492800 C 3.22666600 0.70534000 -0.18375000 C 2.81293000 -0.50978100 -0.79778200 C 3.95977300 -1.83527000 -1.03961800 C 2.46568100 -2.52797900 1.08372000 H 2.05863500 -2.47472900 -0.26756200 H 0.72354500 -1.43115200 1.71045300 C 4.45908000 0.50286500 -0.80165900 C 3.71211100 -1.57332500 -0.74335800 H 2.95195400 1.70830500 0.13069700 H 2.93509700 0.26548100 -1.55058200 C 4.83414800 -0.76828900 -1.23318900 C 3.54393700 -2.58568800 0.19991200 H 4.23687400 -2.83395200 -1.36598200 H 2.32277700 -3.31414800 1.81988200 H 5.12929600 1.34593800 -0.94574400 H 4.54163600 -1.61400400 -1.44395400 H 5.79586000 -0.92460500 -1.71284700 H 4.24286500 -3.41592100 0.24252200 C -1.72305600 -0.62274200 -0.06565200 C -3.03222800 -0.62030100 0.45205000 C -1.26663200 -1.80549000 -0.67934700 TS5* C -3.84331800 -1.74971000 0.38118500 0 1 H -3.41514200 0.27708900 0.93117400 C 0.11464600 -1.08905400 1.73915300 C -2.08392100 -2.92799700 -0.78351500 C -0.74229500 -1.79215000 0.94226300 H -0.25913600 -1.84140600 -1.08602600 C -2.35620900 -0.49708100 -0.41300200 C -3.37070200 -2.90333900 -0.24517600 C -2.70269200 0.39834900 0.61256300 H -4.84454200 -1.73004700 0.80224500 H -1.99205300 0.60019300 1.40995900 H -1.71582900 -3.82508800 -1.27309600 C -3.93164700 1.04851900 0.62807700 H -4.00543800 -3.78266700 -0.31378800 H -4.16226000 1.73752200 1.43609300 C -4.86215700 0.82329300 -0.38745300 Compound 3* analogue H -5.82264200 1.33007200 -0.37782500 0 1 C -4.53770400 -0.05845000 -1.41179100 C 0.43085600 -1.40137700 1.34145200 H -5.24566400 -0.24694000 -2.21439800 C -0.61951900 -1.96226700 0.71317400 C -3.30176700 -0.71057200 -1.42255000 C -2.46385200 -0.64156800 -0.40756700 H -3.08464700 -1.38739300 -2.24143800 C -2.81027600 0.02821400 0.77717500 C -0.97293300 -1.16834700 -0.42990600 H -2.09140900 0.06537700 1.59369100 B 0.15605400 0.03317200 -0.43738300 C -4.05666800 0.62783300 0.93230500 C 0.59337400 -1.44277700 3.11771600 H -4.29596000 1.13880700 1.86079700 H 0.47974600 -0.59894000 3.80791600 C -4.99543700 0.57080800 -0.09749100 H 0.05758800 -2.29430700 3.54270400 H -5.97010000 1.03488000 0.02093800 H 1.66205600 -1.69445100 3.09299800 C -4.66885900 -0.09122000 -1.27797100 C -1.42919700 -3.07430600 1.29245800 H -5.39125700 -0.14790000 -2.08767700 H -2.48778600 -3.01548100 1.01144000 C -3.41662600 -0.68800400 -1.43201900 H -0.99650400 -3.90711300 0.72248400 H -3.19092900 -1.19638600 -2.36404500 H -1.36134600 -3.31992600 2.35423400 C -1.05985700 -1.21986400 -0.55328700 C -0.87137500 -2.20988600 -1.55115900 B -0.06060700 0.01593400 -0.54364100 H -1.67007400 -2.96186500 -1.50783500

103 H -0.92396300 -1.71791500 -2.52830800 H 0.08680600 -2.73399900 -1.51214800 C 0.58460800 0.08069100 1.01824700 C 0.00404600 1.45253900 -1.16158600 C 1.26750500 1.24852800 1.63715100 C 0.60665800 2.62235600 -0.39426600 H -1.06443500 1.67507300 -1.30862400 H 0.42774100 1.46190800 -2.17952900 C 1.18078500 2.53187200 0.82208200 H 0.80070900 1.42449800 2.62173100 H 2.31936800 1.01975600 1.87373700 C 1.81628200 3.67879600 1.57028700 H 2.85524000 3.43038700 1.82541300 H 1.83056600 4.61733000 1.01750400 H 1.29613200 3.85649600 2.52132500 C 0.51577500 3.91496000 -1.17252200 H 1.15806900 3.86311800 -2.06229300 H -0.50894600 4.04848000 -1.53928600 H 0.78880900 4.80909400 -0.61137300 C 1.79381000 -0.58904900 -0.54085300 C 2.75278500 0.25272900 -1.13481400 C 2.18436300 -1.90621900 -0.26798800 C 4.00753400 -0.22448600 -1.50277700 H 2.51301900 1.29234000 -1.33290800 C 3.43414800 -2.39675400 -0.64588300 H 1.50660200 -2.57423200 0.25827900 C 4.35377100 -1.55502900 -1.26518900 H 4.71688600 0.44635200 -1.97994500 H 3.69304500 -3.43073500 -0.43514600 H 5.33497200 -1.92600600 -1.54740300

104

APPENDIX C

Supplementary Information for Chapter Three

Ph B O Ph Ph

25 ºC

-40 ºC

10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 ppm

1 Figure C-1: H NMR Spectra of 3.16 in CDCl3 at 25 ºC and -40 °C.

105

Ph B O Ph Ph

25 ºC

-40 ºC

9.1 9.0 8.9 8.8 8.7 8.6 8.5 8.4 8.3 8.2 8.1 8.0 7.9 7.8 7.7 7.6 7.5 7.4 7.3 7.2 7.1 7.0 6.9 6.8 6.7 6.6 6.5 6.4 6.3 6.2 6.1 ppm

1 Figure C-2: Expansion of H NMR Spectra of 3.16 in CDCl3 at 25 ºC and -40 ºC (aryl region).

106

3 l C D C

1 9 2 0 9 9 8 9 5 7 3 1 7 1 4 3 0 6 9 6 5 3 7 3 0 2 3 7 7 9 9 5 5 4 4 4 2 2 2 2 0 0 3 5 8 4 3 1 1 1 ......

8 8 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 6 6 Ph 1 1 1 1 B O Ph Ph 9 5 4 0 0 8 9 8 1 0 9 9 0 0 0 9 1 9 0 0 ...... 1 1 4 1 5 0 3 2 3 3

10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 ppm

1 Figure C-3: H NMR Spectrum of 3.16 in CDCl3 at -40 ºC.

107

3 l C D C

1 9 2 0 9 9 8 9 5 7 3 1 7 1 9 6 5 3 7 3 0 2 3 7 7 9 9 5 5 4 4 4 2 2 2 2 0 0 3 1 1 1 ...... 8 8 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 6 6 Ph B O Ph Ph 9 5 9 8 1 0 9 9 1 9 0 0 ...... 1 1 4 1 5 0

8.6 8.5 8.4 8.3 8.2 8.1 8.0 7.9 7.8 7.7 7.6 7.5 7.4 7.3 7.2 7.1 7.0 6.9 6.8 6.7 6.6 6.5 6.4 ppm

1 Figure C-4: Expansion of H NMR spectrum of 3.16 in CDCl3 at -40 ºC (aryl region).

108

3 l C D 6 8 7 C 7 1 6 0 2 1 6 8 0 4 6 5

8 2 3 5 8 4 0 5 5 0 5 7 7 3 1 1 1 6 0 8 6 ...... 2 . 1 8 . 1 . 4 0 9 8 7 8 7 6 5 0 . 8 7 6 6 6 6 5 . . . 6 0 7 4 4 4 3 3 3 3 3 2 2 2 2 2 2 2 8 7 7 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 8 7 2 1 1 1

Ph B O Ph Ph

160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 ppm

13 1 Figure C-5: C{ H} NMR Spectrum of 3.16 in CDCl3.

109

6 8 7 7 1 6 0 2 1 6 8 0 4 6 5 2 3 5 8 0 5 5 0 5 7 7 1 6 0 8 ...... 9 8 7 8 7 6 5 0 Ph 8 7 6 6 6 6 5 4 4 4 3 3 3 3 3 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 B O Ph Ph

153 151 149 147 145 143 141 139 137 135 133 131 129 127 125 123 121 119 ppm

13 1 Figure C-6: Expansion of C{ H} NMR spectrum of 3.16 in CDCl3 (aryl region).

110

1 1 . 4

Ph 4 B O Ph Ph

90 80 70 60 50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 ppm

11 1 Figure C-7: B{ H} NMR Spectrum of 3.16 in C6D6.

111

Ph B O Ph Ph

Figure C-8: FT-IR Spectrum of 3.16.

112

3 l

Ph C D C

5 4 9 3 2 1 0 7 7 6 6 8 7 6 6 5 2 3 5 5 5 5 4 4 4 4 2 3 3 3 . . .

B ...... S 7 7 7 7 7 7 7 7 7 7 7 7 2 2 2 0 2 8 5 4 2 0 0 1 8 . . . . . 1 3 3 3 6

9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 ppm

1 Figure C-9: H NMR Spectrum of 3.19 in CDCl3.

113

3 Ph l C D C

3 2 1 0 7 7 6 6 8 7 6 B 6 5 5 5 5 4 4 4 4 2 3 3 3 ...... S 7 7 7 7 7 7 7 7 7 7 7 7 2 5 0 8 . . 1 3

7.76 7.72 7.68 7.64 7.60 7.56 7.52 7.48 7.44 7.40 7.36 7.32 7.28 7.24 7.20 7.16 7.12 ppm

1 Figure C-10: Expansion of H NMR Spectrum of 3.19 in CDCl3 (aryl region).

114

3 l C D 2 3 C 4 7 5

3 2 9 5 6 0 3 0 7 5 7 6 . . . . Ph . . 6 6 8 7 1 . 5 3 2 5 . . . 8 7 . 5 7 5 3 3 3 2 2 9 9 8 B 1 1 1 1 1 1 7 2 1 1 1 S

180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 ppm

13 1 Figure C-11: C{ H} NMR Spectrum of 3.19 in CDCl3.

115

2 3 4 7 5 3 9 0 3 0 7 7 . . . . .

Ph . 5 3 2 5 8 7 5 3 3 3 2 2 B 1 1 1 1 1 1 S

158 156 154 152 150 148 146 144 142 140 138 136 134 132 130 128 126 ppm

13 1 Figure C-12: Expansion of C{ H} NMR Spectrum of 3.19 in CDCl3 (aryl region).

116

8 7 . 9 Ph 4 B S

90 80 70 60 50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 ppm

11 1 Figure C-13: B{ H} NMR Spectrum of 3.19 in CDCl3.

117

Ph B S

Figure C-14: FT-IR Spectrum of 3.19.

118

6 5 . 8 S 2 Ph B Cr OC CO CO

90 80 70 60 50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 ppm

11 1 Figure C-15: B{ H} NMR Spectrum of 3.22 in CDCl3.

119

S Ph B Cr OC CO CO

Figure C-16: FT-IR Spectrum of 3.22.

120

Table C-1: X-ray crystallographic details for compound 3.16 and 3.22.

Compound 3.16 3.22 CCDC # N/A N/A Empirical Formula C27H27BO C17H17BCrO3S FW (g/mol) 378.30 364.17 Crystal System Monoclinic Monoclinic Space Group Cc P 21/c a (Å) 13.4410(8) 11.6053(5) b (Å) 13.1854(8) 9.0311(4) c (Å) 24.0772(16) 15.7982(7) α (deg) 90 90 β (deg) 94.762(2) 102.138(2) ɣ (deg) 90 90 V (Å3) 4252.4(5) 1618.77(12) Z 8 4 -3 Dc (Mg m ) 1.182 1.494 radiation, λ (Å) 0.71073 0.71073 temp (K) 150.0 150.0 R1[I>2σ] 0.0474 0.0362 wR2(F2) 0.1190 0.0935 GOF (S) 1.064 1.065 a 2 2 2 2 1/2 R1(F[I > 2(I)]) = ∑ǁ|Fo| - |Fc |ǁ/ ∑ |Fo|; wR2(F [all data]) = [w(Fo - Fc ) ] ; S(all 2 2 2 1/2 2 data) = [w(Fo - Fc ) /(n - p)] (n = no. of data; p = no. of parameters varied; w = 1/[ 2 2 2 2 (Fo ) + (aP) + bP] where P = (Fo + 2Fc )/3 and a and b are constants suggested by the refinement program.

121

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