Pure Appl. Chem., 2009, Vol. 81, No. 7, pp. 1197-1204
Published online 2009-06-29
From vanadium(V) to vanadium(IV) - and backwards
Abstract: With bidentate alkoxy alkoxide and alkoxy alcohol ligands, respectively, a series of oxovanadium complexes in the oxidation state +4 is synthesized starting from oxovanadium(V) compounds. The reaction of two or more equivalents of 2-methoxyethanol with VOCl3 in n-hexane yields a mixture of the monomeric oxovanadium(IV) complex cis-[VOCl2(HOCH2CH2OMe-κ2O)(HOCH2CH2OMe-κO1)] and the alkoxide-bridged oxovanadium(IV) dimer syn-[VOCl(µ-OCH2CH2OMe-κ2O)]2, which are separated by fractionated crystallization. The same reaction with 2-ethoxy- and 2-iso-propoxyethanol gives only the alkoxide-bridged oxovanadium(IV) dimers anti-[VOCl(µ-OCH2CH2OR-κ2O)]2 (R = Et, iPr). All alkoxide bridged oxovanadium(IV) dimers are furthermore obtained as decomposition products of the chloride-bridged oxovanadium(V) complexes [VO(µ-Cl)Cl(OCH2CH2OR-κ2O)]2 (R = Me, Et, iPr) by Cl2 elimination and react inversely with Cl2 to the vanadium(V) compounds.