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 oxo - vanadium(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-?2O)(HOCH2CH2OMe-?O1)] and the alkoxide-bridged oxovanadium( IV) dimer syn-[VOCl(?-OCH2CH2OMe-?2O)]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(?-OCH2CH2OR-?2O)]2 (R = Et, iPr). All alkoxide-bridged oxovanadium(IV) dimers are furthermore obtained as decomposition products of the chloride-bridged oxovanadium(V) complexes [VO(?- Cl)Cl(OCH2CH2OR-?2O)]2 (R = Me, Et, iPr) by Cl2 elimination and react inversely with Cl2 to the vanadium(V) compounds. © 2009 IUPAC, Publication date (Web): 29 June 2009.