Group 13 Radical and Lewis Acid Chemistry

Since the discovery of frustrated Lewis pairs (FLPs), a pair of sterically encumbered Lewis acids and bases that rapidly activate numerous small molecules, such advances have led to synthetic applications in organic, polymer and radical chemistry. The objective for this thesis is to explore the radical and Lewis acid chemistry of Group 13 compounds at a fundamental level, and their applications in FLP chemistry. Reduction of an N-heterocyclic carbene (NHC) stabilized planar borenium compound led to the generation of a unique diborane compound which rapidly undergoes homolytic cleavage reactions with various substrates. Furthermore, protection with steric bulk on the NHC of the borenium with the combination of the FLP, B(C6F5)3 and tBu3P leads to generation of a boron based dianion radical upon reduction. Combination of tBu3P and E(C6F5)3 (E = B, Al) led to a typical two electron pathway upon treatment with chloranil (p-C6Cl4O2) and Ph3SnH. However, replacing the phosphine with Mes3P resulted in the reaction proceeding through single electron transfer (SET) to the Lewis acids, with homolytic cleavage of the Sn-H bond. Further studies on the SET chemistry between Lewis acids (E(C6F5)3, E = B, Al, Zn(C6F5)2), the reductant Cp*2Fe and conventional weak Lewis bases (chalcogenide species) led to the synthesis of various unique anions and radicals. The results of the stabilization of the weak Lewis acid-base adducts from SET led to the attempts of one electron reduction of the reported unstable (Ph2CN2)B(C¬6F5)3 adducts, resulting in the stabilization of the N2 fragment and activation of C-H bonds. Reactions of hydride abstraction from (IBn)AlH3 resulted in unanticipated redistribution reactions, which gave a rare dicationic aluminum-hydride stabilized by two NHCs (IBn). On the other hand, attempts to prepare the analogous cyclic (alkyl)(amino) carbene (cAAC) alane adducts gave rise to a monomeric neutral aluminum-hydride that rapidly undergoes a 1,2-hydride shift between the Al and carbene carbon centers in solution. Finally, attempts to prepare an ethylene-bridged intramolecular P/Al compounds have been carried out. HAl(C6F5)2 and phosphinoalanes Mes2PAl(C6F5)2 have been successfully generated. While HAl(C6F5)2 enabled the hydroalumination and dehydrocoupling reactions with terminal alkynes, Mes2PAl(C6F5)2 demonstrated the addition across CO2 gas, and reacting with other functional groups.Ph.D