Electronic structure of oxovanadium(IV) complexes of alpha-hydroxycarboxylic acids

A series of (VO)-O-IV bis chelated complexes of alpha-hydroxycarboxylic acids with a 2(COO-, O-) coordination set was analyzed by electronic absorption and EPR spectroscopy in aqueous solution. All the complexes exhibit a square-pyramidal geometry distorted toward trigonal bipyramid. The influence of the distortion of the geometry, as deduced from the steric hindrance produced by the substituents at the alpha-carbon atom of the ligands, on the spectroscopic parameters has been studied. The observed trends were related to the electronic structure of the metal ion in the distorted geometry.