In Search of a Versatile Pathway to ansa-Chromocene Complexes. Synthesis and Characterization of the Highly Unstable ansa-Chromocene Carbonyl Complex Me2C(C5H4)2CrCO

In an effort to develop a general synthetic route to ansa-chromocene complexes with diverse ligand frameworks, we investigated ansa-magnesocene compounds as an alternative, potentially more versatile ligand source than ansa-calcocene compounds. The first single-carbon-bridged ansa-chromocene compound, Me2C(C5H4)2CrCO, was isolated from the reaction between Me2C(C5H4)2Mg and CrCl2 in THF under an atmosphere of carbon monoxide. This new ansa-chromocene compound is considerably more air-sensitive and less chemically stable than its ethanediyl-bridged counterparts.