Synthesis and properties of isocyanate and isothiocyanate d1- and d2-complexes of vanadocene

Article abstract of DOI:10.1016/0022-328X(87)80067-0

The reactions of vanadocene and its halides Cp2VCl and Cp2VCl2 with R3MNCX (M = Sn, Si, X = O, S) and R2M(NCX)2 in various molar ratios have been studied.The reactions proceed either by an exchange of groups, with no change in the oxidation state of vanadium, or by an oxidative addition of pseudohalide ligand: V^II -> V^III; V^III -> V^IV.Oxidative addition results in the formation of (R3M)2 or gaseous hydrogen (in the reaction with HCl) in the reaction products.We have prepared the first ever monomeric and readily oxidisable d²-complexes of V^III of Cp2VNCX-type and asymmetric d¹-complexes of Cp2V(Cl)NCX type, which, although rather stable in air, undergo disproportionation into symmetric d¹-complexes on heating.In transmetallation reactions the ligand activity is found to increase in the order Cl < NCO < NCS.The complexes were characterised by GLC analysis, IR and ESR spectroscopy.A general scheme for the disproportionation reaction of asymmetric complexes of vanadocene is supported by differential thermal analysis data.