Chemistry of alkoxo-bonded oxovanadium(v) complexes incorporating azophenolcarboxylates and ethylene glycol

The reaction of V^(IV)O(L)(H2O) (where L = tridentate dinegative ONO donor azo ligands) with ethane-1,2-diol (H2ed) in methanol solution produces the complex V^v O(L) (Hed) (in which H^cd coordinates in a monodeprotonated fashion) via aerial oxidation. The coordination sphere of the complexes is of the VO(ONO)(00) type, where 0 atoms are of oxo, phenolic, alcoholic and carboxylic and N is of azo type. The complexes arc diamagnetic and exhibit only one ligand-to-metal charge transfer (LMCT) transition near 490 nm in addition to other two intra-ligand transitions around 410 and 330 nm. The complexes have low V(V)/V(IV) reduction potentials in the region -0.40 V vs SCE leading to the stabilisation of pentavalent state.