The coupling chemistry of metal pentadienyl compounds with alkynes and imines: Unique carbon-carbon and carbon-nitrogen agostic interactions.

摘要

The coupling chemistry of titanium octadienyl compounds with alkynes has been expanded and a nonclassical C-C agostic interaction in "(C5H5)Ti(c&barbelow;-C8H11 )(C6H5CC-SiMe3)2(PMe 3)" has been studied through INADEQUATE NMR spectroscopy. Additionally, zirconium octadienyl and dimethylcyclohexadienyl complexes have been allowed to react with alkynes to form a variety of novel cage-like structures. In conjunction with the alkyne coupling research, 16 e- and 18 e- Cp and Cp* based metallacyclobutanes of both group IV and group VI metals have been studied to determine if the electron deficient group IV complexes possess similar C-C agostic interactions. The metallacyclobutanes of Ti and Zr exhibited C-C coupling constants in the range of 20--24 Hz, while the Mo and W compounds were in the range of 30--32 Hz.; An electron density study of Zr(C7H11)(C6 H5CH = NCH(CH3)2) was performed and provided ambiguous results regarding the nature of a potential Zr-(C-N) agostic interaction in the molecule. The study marked the first zirconium compound to be studied by this experimental technique and revealed, among other interesting information, the key orbitals involved in the bonding of the zirconium center. In an effort to expand imine coupling chemistry to hafnium, the synthesis of Hf(C7H11)2PR3 compounds was improved and the products structurally characterized. Additionally, half-open and open titanium pentadienyl compounds were allowed to react with imines, resulting in the isolation and characterization of several new compounds.; In a significant shift from pentadienyl coupling chemistry, a new series of ruthenium coordination compounds with ligands such as pyrazole and pyridazine was synthesized for the purpose of producing heterobimetallic compounds maintaining multiple bonds between the two metal centers. Several reactions of these ruthenium complexes with W and Mo coordination compounds resulted mainly in ligand exchange reactions.