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Small Molecule Activation with Main Group Complexes

The synthesis of monodentate biphenyl-amido proligands is reported as well as a series of complexes of lithium with these ligand systems. The solid-state molecular structure of these lithium amides are described as well as their use as synthons in the preparation of amido-arene aluminum complexes. Structural and spectroscopic data suggest that these species exhibit weak arene to metal donation. Attempts to generate aluminum cations from these species are detailed. A new synthetic route to titanium “constrained geometry” precatalysts was utilized to prepare a series of titanium complexes with similar pendant arene groups. The homopolymerization activity of these catalyst systems with ethylene and styrene is detailed.
Combination of a sterically encumbered phosphine and large, electrophilic borane was used to effect heterolytic cleavage of disulfides to afford novel thiophosphoniumthioborate salts. A series of exchange reactions demonstrated the facile reversal of this reaction. Similar phosphine-borane systems are found to exhibit divergent reactivity with terminal alkynes, affording either phosphonium-alkynylborate salts from deprotonation or phosphonium-vinyl-borate zwitterions from addition. The scope of Lewis acid, Lewis base and alkyne combinations used to effect similar reactivity is detailed. It was found that the reaction of pyrroles, boranes, and alkynes formed similar addition products that were found to undergo further reactivity to afford C-vinyl pyrroles and nitrogen-boron bicyclic compounds. The synthesis of N-alkyl-bis(pentafluorophenyl)boryl amidinates is presented. The reactivity of these compounds with a variety of small molecules is reported. Reaction with CO2, CO, di-iso-propylcarbodiimide, tert-butyl isocyanide, and benzaldehyde as well as thermally-induced intramolecular rearrangement of these compounds affords a variety of novel nitrogen-boron heterocycles.

Identiferoai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/26505
Date16 March 2011
CreatorsDureen, Meghan Adrienne
ContributorsStephan, Douglas
Source SetsUniversity of Toronto
Languageen_ca
Detected LanguageEnglish
TypeThesis

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