Novel Tridentate N,S,N-Metal Compounds of Zinc, Germanium and Phosphorus
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Novel Tridentate N,S,N-Metal Compounds of Zinc, Germanium and Phosphorus John Lortie, BSc Chemistry Supervisor: Dr. G. Nikonov Department of Chemistry Faculty of Mathematics and Science Brock University St. Catharines, Ontario Thesis submitted in partial requirement for the degree of Master of Science Abstract A novel ligand based on a flexible NSN tridentate framework, and main group compounds of the general formula M(NSN) were prepared on zinc, germanium, and phosphorus. The compound ZnNSN(dimethylaminopyridine) (III-45a) is fluxional with III-46a in tetrahydrofuran, and its exchange parameters were calculated from NMR measurements. An X-ray structure was obtained for GeNSN (III-47a) crystals isolated from diethylether and exhibits an envelope-like geometry with coordination of the soft sulfur donor to the germanium centre. III-47a was not reactive with CH3I but showed reactivity with 3,6-di-tert-butyl-o-benzoquinone. ClPNSN (III-53) was prepared both by transmetallation of III-46a and by a reaction of an in situ generated Li2NSN and PCl3. HPNSN (III-52) was prepared by halogen exchange of III-53 and L-selectride. i Acknowledgements First and foremost, my most sincere appreciation goes to my supervisor Dr. Georgii Nikonov who has been a monumental influence on me. His passion and excitement for research is inspiring, and I am grateful for being fortunate enough to work with such a creative and innovative professor over the past several years. Thank you for your patience, and for providing an environment which fosters creativity and the opportunity to grow. Thank you to my committee members Dr. Martin Lemaire, Dr. Art Van der Est, and Dr. John Corrigan from Western for their time and valuable feedback in the preparation of this dissertation. Also, the support by the excellent staff at Brock, including Jennifer Roberts, Marie Harris, Irene Palumbo, Alison Moffat, glassblower Jordan Vandenhoff, and technical assistance for NMR experiments by Razvan Simionescu have been invaluable for bringing this project to fruition. I must also thank my friends and colleagues whom I was fortunate to spend time with in the Nikonov group. Thank you to Dr. Van Hung Mai, Dr. Terry Chu, Dr. Minh Tho Nguyen, and Dr. Iryna Alshakova for demonstrating true excellence, and to Josh Clarke, Jan-Willem Lamberink, Joseph Cartwright, Anton Dmitrienko, Aisha Kassymbek, Aliona Baradzenka, Brandon Corbett, and Billy Petrushko for all your encouragement and the great times together. It was a pleasure to learn alongside such talented researchers. Acknowledgements extend to the other graduate students in the chemistry department, especially to the groups of Drs. Dudding, Metallinos, Hudlicky, Lemaire, Yan, Atkinson, Zelisko and Pilkington for their friendship over the years. Thank you to my girlfriend Jen who has been with me through long nights of writing and drinking too much coffee, and for our relaxing evenings out which also often involved winding up ii at that same coffee shop. Her ambition is as contagious as her laughter, and I can always count on her positivity to brighten up a room. I could not have asked for a better partner and I am excited for our future together. Finally, I could have not accomplished this without my family. I will forever be in their debt for the sacrifices made which helped me reach this point. To my mom and grandma, thank you for your continuous love and support throughout my entire education, even during difficult times and when it required moving away. I would like to thank my dad and the rest of my family for their support and encouragement in my decision to pursue further education. I hope that I have made my late Papa and all of you proud. iii Table of Contents Abstract ...................................................................................................................................... i Acknowledgements .................................................................................................................... ii List of Schemes ...........................................................................................................................v List of Figures ......................................................................................................................... viii List of Abbreviations................................................................................................................ xii I. Introduction .............................................................................................................................1 II. Background Review ...............................................................................................................5 II.1 Small Molecule Activation ................................................................................................5 II.1.1 Non-Innocent Ligands .............................................................................................. 11 II.1.2 Small Molecule Activations by Group 12 Compounds .............................................. 17 II.1.3 Small Molecule Activations by Group 13 Compounds .............................................. 20 II.1.4 Small Molecule Activations by Group 14 Compounds .............................................. 27 II.1.5 Small Molecule Activations by Group 15 Compounds .............................................. 35 II.2 Zinc Catalyzed Cross-Coupling ....................................................................................... 46 II.3 Project Goals ................................................................................................................... 52 III. Results and Discussion ........................................................................................................ 53 III.1 Ligand Synthesis ............................................................................................................ 53 III.1.1 Attempts to Synthesize the NNN ligands ................................................................. 54 III.1.2 Synthesis of the NSN Ligand ................................................................................... 61 III.2 Main Group Compounds Supported by NSN Ligand ...................................................... 72 III.2.1 Synthesis of Zinc Compounds Supported by NSN Ligand ....................................... 74 III.2.2 Synthesis and Reactivity of Germanium Compounds Stabilized by NSN Ligand ..... 78 III.2.3 Synthesis and Reactivity of Phosphorus Compounds Supported by NSN Ligand ..... 84 IV. Conclusions and Future Work ............................................................................................. 89 V. Experimental ........................................................................................................................ 90 VI. References ........................................................................................................................ 108 iv List of Schemes Scheme 1. Activation of dihydrogen by a germanium analogue of an alkyne. ..............................1 Scheme 2. First examples of boryl anion and aluminyl anions and reactions.[12,13] .......................4 [21] Scheme 3. Example of germylene reactivity for activation of H2 and NH3 by Power. ..............8 Scheme 4. Synthesis and reactivity of the first FLP to demonstrate reversible hydrogen splitting. ................................................................................................................................................. 10 Scheme 5. Representative structures of 1,2-chelating species as X2, LX, or L2 ligands. ............. 13 Scheme 6. Redox non innocent β-diketiminate ligand on zinc and cobalt.[45] ............................. 15 Scheme 7. Fe(PNN) complex with two canonical forms.[50] ....................................................... 17 Scheme 8. Mechanism for hydrogenation of imines catalyzed by an in situ generated zinc hydride, following hydrogenolysis.[56] ....................................................................................... 20 Scheme 9. Non-innocence of bis(amine) ligand. ........................................................................ 22 Scheme 10. Reactivity of aluminum complex stabilized by a pyrazole functionalized ligand. .... 24 Scheme 11. Various nucleophilic reactivities of aluminyl anion I-8. .......................................... 26 Scheme 12. Phosphino carbene prepared by Bertrand.[70]........................................................... 28 Scheme 13. Diaminocarbene and alkylaminocarbene reactions.[17] ............................................ 29 Scheme 14. Silane, borane, and P-H activation by NHCs.[75,76] Reactions reported for both saturated and unsaturated NHCs, except where bolded. ............................................................. 30 Scheme 15. Resonance structures and representations for carbene-phosphinidene adducts......... 31 Scheme 16. Isomers of chlorophosphinidenes.[79] ...................................................................... 31 Scheme 17. Various NacNacGe chemistries.[84–87] ..................................................................... 33 Scheme 18. Preparation of stabilized heavy analogues of CO and CO2. .................................... 34 Scheme 19. Best descriptions of orbitals in ADPO (II-77).[92] ................................................... 36 Scheme 20. Electromorphic representations for ADPO (II-77) by Arduengo III.[91] ................... 37 v Scheme 21. Bent 8-P-3 implicated as transition state in dimerization.