From vanadium(V) to vanadium(IV) - and backwards

Rosenthal, Esther C. E.

doi:10.1351/PAC-CON-08-08-32

Pure Appl. Chem., 2009, Vol. 81, No. 7, pp. 1197-1204

http://dx.doi.org/10.1351/PAC-CON-08-08-32

Published online 2009-06-29

From vanadium(V) to vanadium(IV) - and backwards

Esther C. E. Rosenthal

Department of Chemistry, Technische Universiät Berlin, 10623 Berlin, Germany

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.