ChemInform Abstract: Organometallic Chemistry of Molybdenum and Tungsten Supported by Alkoxide Ligands

Abstract

Publisher Summary This chapter discusses the organometallic chemistry of molybdenum and tungsten alkoxides, according to ligand type Organotransition metal chemistry has largely developed with the support of soft, π acceptor ligands, such as carbon monoxide, tertiary phosphines, and cyclopentadienyls. The successive replacement of alkoxide ligands by the poor π-donor halide ligands results in a progressive and substantial downfield shift in the resonance for the alkylidene Cα, reflecting an increasing electron deficiency at this site. The most important aspect of the reactivity of alkylidene alkoxide complexes is their ability to catalyze alkene metathesis. The several examples of alkylidene complexes with β-hydrogens prepared by Osborn's group are unprecedented for unsaturated complexes. The most important aspect of the reactivity of alkylidyne alkoxide complexes is their ability to catalyze the metathesis of alkynes. Several of the metallacyclic compounds have been characterized by X-ray crystallography, confirming proposed geometries and providing insights into the function of supporting ligands and the nature of catalytic intermediates. The most significant aspect of tungstenacyclobutadiene chemistry is the prospect that the compounds are intermediates in catalytic alkyne metathesis.