Synthesis, characterization, and computational studies of unsaturated transition metal complexes

The design of metal compounds that are electronically and coordinatively unsaturated has given rise to a wealth of diverse reactivity and thus potential application in a wide variety of chemical processes. These compounds can coordinate and cleave strong bonds (C-H, C-C, Si-H, C-F) and activate normally unreactive molecules (H2, N2, CO), allowing the addition of new functionality to organic molecules. The catalytic transformation of simple molecules (hydrogenation, hydroformylation, hydrosilation, olefin metathesis polymerization) assisted by such unsaturated complexes is also commonly used in the chemical and industrial laboratory.; This work explores the synthesis and reactivity of unsaturated metal species. Several methods of stabilizing electron deficient metal centers are explored including the use of a bulky diphosphino amide of the Fryzuk ligand class as a supporting ligand for the metal (Ru and Os). Because of this good donor ligand, mononuclear unsaturated 16---and even 14---electron complexes are able to be synthesized and their reactivity toward a variety of substrates explored. The donor properties of a saturated and unsaturated version of a popular "phosphine substitute," the Arduengo carbene, are also studied in order to better predict the amount of electronic stabilization that can be offered an unsaturated metal center by this ligand type.; The mechanism of reaction of incoming substrates with unsaturated transition metal complexes is also of interest. In order to investigate the interaction of pi-donor substituted olefins with unsaturated complexes, the reactivity of Cp2ZrHCl toward vinyl fluoride along with the mechanism of C-F activation as well as the structure of pi-donor substituted olefin complexes [CpFe(CO)2(H2CCHDo)]PF6, D o = OEt and NMe2 has been studied. Finally, the mechanism of Rh mediated allylic alkylation reactions, which also involve an unsaturated metal center, is explored.