Vanadocene complexes with asymmetric alkyne ligands, [Cp2V(1-2η-R1C=CR2)

Abstract

A number of vanadocene complexes with asymmetrically substituted acetylenes, [Cp2V-(1-2η-R1C=CR2)] (R1 = Ph and SiMe2Ph; R2 = 4-biphenyl, 1-naphthyl, and Ge(CF3)3), were obtained and examined by ESR spectroscopy. The isotropic and anisotropic ESR spectra of the complexes containing the phenyl, biphenyl, naphthyl, or dimethyl(phenyl)silyl substituent in the alkyne ligand are typical of d1 complexes of vanadocene with alkynes. This is not the case of the complex containing the electron-withdrawing tris(trifluoromethyl)germyl group, whose isotropic and anisotropic ESR spectra show anomalous values of g factor and hyperfine coupling constant.