Properties and Reactivity of Pd(I) Bridging Allyl Dimers

This thesis summarizes an extensive study into the properties and reactivity of binuclear Pd1 complexes supported by bridging allyl ligands (Pd1 micro-allyl dimers). Chapter 1 is a review of the prior work on Pd1 micro-ally dimers. Prior to our work, numerous examples of Pd1 micro-allyl dimers and related complexes had been characterized. The Pd1 micro-allyl dimers were generally treated as relatively unreactive side products of reaction mixtures that were meant to study the Pd0 and Pd11 oxidation state. Chapter 2 summarizes a detailed mechanistic study of the CO2 insertion into (micro-allyl)2Pd2(L) 2, type dimers. These Pd1 micro-allyl dimers supported by two micro-allyl ligands react as nucleophiles under relatively mild reaction conditions because of the presence of a high-lying HOMO that is localized on the terminal carbons of the micro-allyl ligands. Chapters 3 and 4 explore the role of (micro-allyl)(micro-Cl)Pd2,(L)2, type dimers in cross-coupling catalysis. These dieters are proposed to access the catalytically active L-Pd0 catalyst for catalysis through disproportionation. The formation of (micro-allyl)(micro-Cl)Pd2,(L)2 type dimers from Pd(L)eta3-allyl)C1 type precatalysts under catalytic reaction conditions is also explored. We conclude that this is a deleterious process that removes the active catalyst from the reaction mixture.