Some bimetallic half sandwich iron complexes with metal carbene substitution at the cyclopentadienyl ligand: synthesis, characterization, structure, and cyclic voltammetry
Abstract
The first half sandwich cyclopentadienyl complexes 2–5 with a carbene complex subtituent at the cyclopentadienyl ring are presented. These complexes deserve interest because one metal atom (Cr, Mo, W, Fe) is incorporated in the π system of the ligand in conjugation to the cyclopentadienyl ring complexed to iron. In addition to intermetallic interactions these complexes offer the possibility of reactions at both metal atoms. An X-ray structure analysis of 2 reveals, however, that the carbene–chromium π bond is not perfectly coplanar with the cyclopentadienyl ring. Cyclic voltammetry of some of the complexes prepared shows a decrease in oxidation potential upon carbene complex substitution at the cyclopentadienyl ring for 2 and 7 by 118 and 63 mV, respectively. A ligand exchange reaction with bis(diphenylphosphino)ethane (dppe) under irradiation results in the incorporation of two dppe molecules.