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Exploring the Synthesis, Structure, and Reactivity of Phosphorus- Chalcogen Heterocycles

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Exploring the Synthesis, Structure, and Reactivity of Phosphorus- Chalcogen Heterocycles Western University Scholarship@Western Electronic Thesis and Dissertation Repository 2-27-2018 10:30 AM Exploring the Synthesis, Structure, and Reactivity of Phosphorus- Chalcogen Heterocycles Cameron Graham The University of Western Ontario Supervisor Ragogna, Paul J. The University of Western Ontario Graduate Program in Chemistry A thesis submitted in partial fulfillment of the equirr ements for the degree in Doctor of Philosophy © Cameron Graham 2018 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Inorganic Chemistry Commons Recommended Citation Graham, Cameron, "Exploring the Synthesis, Structure, and Reactivity of Phosphorus-Chalcogen Heterocycles" (2018). Electronic Thesis and Dissertation Repository. 5258. https://ir.lib.uwo.ca/etd/5258 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. Abstract In recent years, low-coordinate main group chemistry has seen significant research interest due to the isolation of structures that demonstrate unique bonding and reactivity. Conversely, the area of phosphinidene chalcogenides, a low-coordinate phosphorus and chalcogen species, have yet to be thoroughly explored. In this context, this dissertation describes the synthesis of a number of phosphorus-chalcogen heterocycles that can be degraded to provide stoichiometric access to low-coordinate phosphorus species. The ability for successful P-Ch transfer relies on using a bulky m-terphenyl group at phosphorus that provides enough steric bulk to kinetically stabilize the phosphorus centre but is also accommodating enough to allow for further reactivity. Previous attempts at this chemistry have utilized more sterically accommodating ligands, however sterically demanding ligands have now been proven to be critical in controlling the fragmentation and transfer of these generated species. In Chapter 2, the synthesis of strained P-Ch heterocycles containing a 4- membered core will be discussed, as well as attempts to use these cyclic structures to gain access to low-coordinate phosphinidene chalcogenides. Chapter 3 continues from the success discussed in the previous chapter and uses these newly generated rings as P-Ch transfer reagents for reactions with alkynes. An alternative method of generating phosphinidene chalcogenides that mitigates the synthesis of P-Ch heterocycles will also be discussed. Chapter 4 explores the reactivity of these 4-membered rings using Lewis acids and bases, again linking these compounds to the monomeric phosphinidene chalcogenides. Chapter 5 introduces the idea of combining two different low-coordinate phosphorus compounds (both generated from their parent dimer heterocycles) to generate a new heterocycle containing elements from Group 13, 15 and 16. The highlight of this thesis is discovering new methods of generating and trapping phosphinidene chalcogenides. While the sulfur derivatives have been discussed in the literature, the chemistry surround the selenium compounds are unique and include some of the first structural confirmation of such species. All of the compounds discussed in this thesis were characterized to the fullest extent using a range of solution and solid-state techniques, with an emphasis on NMR spectroscopy and single crystal X-ray crystallography. i Keywords Phosphorus • Chalcogen • Coordination Chemistry • Phosphinidene Chalcogenide • Structure and Bonding • Low-coordinate Main Group Chemistry • Heterocycles • ii Co-Authorship Statement This thesis includes work from four published manuscripts in chapters two, three, four, and five. The article presented in chapter two were co-authored by C. M. E. Graham, T. E. Pritchard, P. D. Boyle, J. Valjus, H. M. Tuononen, and P. J. Ragogna (Angew. Chem. Int. Ed. 2017, 56, 6236-6240). TEP was responsible for a portion of the cycloaddition chemistry, and this was conducted in her fourth-year thesis project under the direct supervision of CMEG. CMEG performed the majority of synthesis and comprehensive characterization of the compounds reported and collected and refined all X-ray diffraction data with some assistance from PDB. CMEG assembled the manuscript with some assistance from TEP. HMT and JV were responsible for the comprehensive DFT calculations for the manuscript, and responsible for the corresponding section in the manuscript. HMT and PJR edited the manuscript. The work described in chapter three was co-authored by C. M. E. Graham, C. L. B. Macdonald, P. D. Boyle, J. A. Wisner, and P. J. Ragogna (Chem. – Eur. J. 2018, 24, 743- 749). CMEG was responsible for the synthesis and characterization of all compounds reported, collected and refined all X-ray diffraction data with some assistance from PDB, and assembled the manuscript. CLBM was responsible for the comprehensive computational experiments, and the corresponding section in the manuscript. JAW provided insight on the different mechanistic pathways reported in the manuscript. CLBM and PJR edited the manuscript. The work described in chapter four was co-authored by C. M. E. Graham, J. Valjus, P. D. Boyle, T. E. Pritchard, H. M. Tuononen, and P. J. Ragogna (Inorg. Chem. 2017, 56, 13500-13509). TEP was responsible for a portion of the coinage-metal induced ring expansion chemistry, and this was conducted in her fourth-year thesis project – under the direct supervision of CMEG. CMEG conducted the synthesis and comprehensive characterization of the compounds reported and collected and refined all X-ray diffraction data with some assistance from PDB. CMEG assembled the manuscript with some assistance from TEP. HMT and JV were responsible for the comprehensive DFT calculations for the iii manuscript, and responsible for the corresponding section in the manuscript. HMT and PJR edited the manuscripts. The work described in chapter five was co-authored by C. M. E. Graham, C. R. P. Millet, A. N. Price, J. Valjus, M. J. Cowley, H. M. Tuononen, and P. J. Ragogna (Chem. – Eur. J. 2017, 24, 672-680). The synthesis, characterization and reactivity studies of 5.3Ch was a collaborative work between CRPM, ANP, and CMEG: the sulfur derivative by CRMP and ANP, and the selenium analogue by CMEG. CMEG collected and refined all X-ray diffraction data and assembled the manuscript. HMT and JV were responsible for the comprehensive DFT calculations for the manuscript, and responsible for the corresponding section in the manuscript. MJC, HMT, and PJR edited the manuscripts. iv Acknowledgements I would like to thank my supervisor Paul Ragogna for his continuous support throughout the duration of my Ph.D. Paul unquestionably improved my research and technical skills, pushed me to think outside the box, and enforced critical thinking – I certainly would not be the scientist I am today if it was not for his guidance. I appreciate Paul’s patience when it came to writing manuscripts and going through our editing process. At times, it was a daunting task to have a supervisor that was more excited about my research than I was, but I truly appreciate his enthusiasm in chemistry, and my scientific approach has been heavily influenced by his mentality. Paul’s intensity towards research is contagious, and I would not have been able to push myself in our projects if it wasn’t for his encouragement. I thank Paul for the countless thrilling conversations, life advice, strongly influencing my taste in beer, and allowing me to beat him at squash. All of the graduate students, past and present, of the Ragogna group that I had the pleasure to work with: Jonathan, Ryan, Mahboubeh, Yuqinq, Tyler, Vanessa, Benjamin, Tristan, Soheil, Matt, and Taylor – thank you! We have all shared countless great memories, exciting conversations (some over a beer or two), and all of you helped create a group dynamic where it was enjoyable to come into the lab every day. It would have been a difficult task to manage graduate school without all of you. Thanks to Jonathan for showing me the ropes when I started in the group and instilling in me the Ragogna group demeanor – it’s a shame you weren’t around for longer! Thanks to Tyler for introducing me to the game of squash, and for the fun rounds of golf – you always helped give me something to think about other than chemistry. Thanks to Vanessa and Taylor, my main group partners in crime and lab mates over the years. Vanessa, thank you for broadening my taste in music, even though that meant going through a serious Abba phase. Vanessa’s enthusiasm towards chemistry is unparalleled, and you always made the lab an extremely fun place to work, and I hope you always keep the same frame of mind. Your mannerisms always helped to keep a calm vibe in the lab which was crucial when the results just weren’t there. Taylor, thank you for all of the good glovebox chats, and brainstorming ideas which generally resulted in me telling you to try some crazy idea that wouldn’t end up working. Thanks to Matt for all of our great office conversations, showing me how to make a delicious home brew, and to his v appreciation for how difficult Microsoft Word can be at times. Thank you to the undergraduate students that I had the pleasure of mentoring: Chrissy, Taylor, and Deeksha. I appreciate all of your hard work and positive attitudes that made it a pleasure to mentor each of you, and you all helped add a number of pages to this document. During my graduate school career, I had the pleasure of working with a number of collaborators from around the world including Charles Macdonald, Heikki Tuononen, Michael Cowley, and Phil Power. Thank you, Chuck and Heikki, for your timely calculations, and for helping us make sense of our results. Thank you, Mike and Phil, for sending us some of the compounds created in your lab and allowing us to explore some unique chemistry. Western University has a talented and hardworking staff that made a large portion of this thesis possible.
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