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Computational Investigations of Organometallic Polymerization

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Computational Investigations of Organometallic Polymerization Computational Investigations of Organometallic Polymerization Catalyst Reaction Mechanisms by Andrew K. Vitek A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Chemistry) in the University of Michigan 2019 Doctoral Committee: Associate Professor Paul Zimmerman, Chair Professor John Kieffer Professor Anne J. McNeil Associate Professor Nathaniel K. Szymczak Andrew K. Vitek [email protected] ORCID iD: 0000-0002-8940-6829 © Andrew K. Vitek 2019 Dedication To my parents, whose sacrifices make me forever humble. And to my mentors, whose wisdom make me forever grateful. Thank you. ii Acknowledgements I will be forever grateful for my time spent in Ann Arbor at the University of Michigan. I owe much of my personal growth and many of my accomplishments to the mentors, colleagues, and friends that I met here. I would first like to acknowledge my advisor, Professor Paul Zimmerman, for his guidance, encouragement, and support. Paul exemplifies all the leadership qualities that one could ask for in an advisor. Paul’s sharp mind, patience, and unique knack for motivation had an immeasurable influence on the scope and quality of my graduate work. Paul’s mentorship has greatly improved my abilities as a scientist. I would also like to thank Professor Anne McNeil for her continual feedback on most of the projects contained in this thesis. I am lucky to have collaborated with Professor McNeil, her group, and other great minds in the polymer chemistry field that I have connected with through her. I am also grateful for my time spent working with Professor Nathaniel Szymczak. Experimental chemistry experience is necessary to keep computational chemists grounded with real chemistry, and I appreciated the opportunity to work in Professor Szymczak’s lab. I greatly appreciate Professors John Kieffer, Anne McNeil, and Nathaniel Szymczak for serving on my committee and providing feedback and advice during my graduate career. Thank you to past and current members of the Zimmerman lab for challenging and helping me throughout my time in graduate school. I am excited to read your future works and witness your future accomplishments. Thank you to my friends and family for enriching my life in so many meaningful ways. To Casey Vitek, Alan Chien, Ben Meinen, David Lee, and Josh Damron. Thank you for lending your time and attention on our various adventures. Finally, thank you to the thoughtful and loving Sydney Faylor and the Faylor family. You are the reason that Ann Arbor is – and will always be – home. iii Table of Contents Dedication ....................................................................................................................................... ii Acknowledgements ........................................................................................................................ iii Table of Contents ........................................................................................................................... iv List of Figures ................................................................................................................................ vi List of Tables ................................................................................................................................ xii List of Equations .......................................................................................................................... xiii List of Appendices ....................................................................................................................... xiv Abstract ......................................................................................................................................... xv Chapter 1: Introduction ................................................................................................................... 1 1.1 Investigating Reaction Pathways with Computational Chemistry ....................................... 1 1.2 Chemical Space, Potential Energy Surfaces, and Predicting Reaction Rates ....................... 2 1.3 Transition State Finding Methods ......................................................................................... 6 1.4 Transition State Finding via Growing String Methods ......................................................... 8 1.5 Dissertation Outline .............................................................................................................. 9 1.6 References ........................................................................................................................... 11 Chapter 2: Applications of Pathway Exploration Methods on Chemical Systems ....................... 13 2.1 Pathway Exploration of Olefin-Thiophene Copolymerization Switching Catalysis Mechanism ................................................................................................................................ 13 2.1.1. Introduction ................................................................................................................. 13 2.1.2. Discussion ................................................................................................................... 16 2.1.3. Conclusions ................................................................................................................. 18 2.2 Determining Source for Non-Living Thiophene Polymerization via Nickel Diimines ...... 19 2.2.1. Introduction ................................................................................................................. 19 2.2.2. Discussion ................................................................................................................... 21 2.2.3. Conclusions ................................................................................................................. 22 iv 2.3 Enantioselective Epoxide Polymerization via Bimetallic Chromium Catalysts – Determining the Source for Enantioselectivity ......................................................................... 23 2.3.1. Introduction ................................................................................................................. 23 2.3.2. Discussion ................................................................................................................... 24 2.4 Conclusions ......................................................................................................................... 30 2.5 References ........................................................................................................................... 31 Chapter 3: Transmetalation Mechanism in Nickel(II)-Catalyzed Grignard Reactions ................ 34 3.1 Abstract ............................................................................................................................... 34 3.2 Introduction ......................................................................................................................... 34 3.3 Results and Discussion ....................................................................................................... 36 3.4 Ligand Control of Spin State .............................................................................................. 38 3.5 Transmetalation Initiation Mechanism ............................................................................... 44 3.6 Transmetalation Propagation Mechanism .......................................................................... 47 3.7 Conclusion .......................................................................................................................... 49 3.8 Experimental Details ........................................................................................................... 50 3.9 Computational Details ........................................................................................................ 51 3.10 References ......................................................................................................................... 52 Chapter 4: Revealing the Strong Relationships between Ligand Conformers and Activation Barriers: A Case Study of Bisphosphine Reductive Elimination ................................................. 60 4.1 Abstract ............................................................................................................................... 60 4.2 Introduction ......................................................................................................................... 60 4.3 Results and Discussion ....................................................................................................... 63 4.4 Conclusions ......................................................................................................................... 77 4.5 Computational Details ........................................................................................................ 78 4.6 References ........................................................................................................................... 79 Chapter 5: Final Remarks ............................................................................................................. 84 5.1 Research Summary ............................................................................................................. 84 5.2 Future Considerations for Related Works .......................................................................... 88 5.3 Final Thoughts ...................................................................................................................
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