| The research presented in this dissertation had two primary goals---to prepare a variety of nickel and palladium pincer-containing hydrides, and then to investigate these complexes to activate molecular O2 for the selective partial oxidation, including epoxidation, of olefins. Additionally, the reaction of molecular O2 with a related titanium hydride is also described.;The highlights of the palladium work included the synthesis and characterization of Pd-H complexes, which when evaluated proved to be reactive with molecular O2. A palladium hydroperoxide complex was also structurally-characterized. Additionally, a novel Pd-H adduct with K-SelectrideRTM reagent was prepared and characterized. The O-atom transfer ability of these complexes was investigated through the reaction of an olefin with in situ formed Pd-OOH. Although no evidence was observed indicating the epoxidation of olefins, these Pd-OOH species proved capable of selectively oxidizing tert-butyl isocyanide to the isocyanate.;Several novel pincer nickel hydride complexes were prepared and characterized, and subjected to reactions with oxygen. Unfortunately, the isolation of a pure nickel hydroperoxide was not accomplished. The reactive species formed via the reaction of molecular O2 and PCP-Ni-H resulted in ligand decomposition via a unique reaction that oxidized the alkyl groups attached to the phosphine arms. No O-atom transfer to olefins was observed. An attempt to prepare a novel Ti-OOH species through the reaction of O2 and a Ti-H resulted in an unexpected, structurally-characterized, mu-oxo titanium dimer. It is possible that this dimeric species was formed via the initial formation of a highly-reactive titanium hydroperoxide. |
