Stereospecific formation of α-hydroxycarboxylato oxo peroxo complexes of vanadium(V). Crystal structure of (NBu 4) 2[V 2O 2(O 2) 2( l-lact) 2]·2H 2O and (NBu 4) 2[V 2O 2(O 2) 2( d-lact)( l-lact)]·2H 2O

Abstract

An overview of structurally characterized α-hydroxycarboxylatodioxo- and α-hydroxycarboxylatooxoperoxovanadates(V) is presented and the geometric parameters of the V 2O 2 bridging core are discussed. The first case of a stereospecific formation of oxoperoxovanadates(V) is reported: The crystal structures of the isomeric compounds (NBu 4) 2[V 2O 2(O 2) 2( l-lact) 2]·2H 2O and (NBu 4) 2[V 2O 2(O 2) 2( d-lact)( l-lact)]·2H 2O (lact=C 3H 4O 3 2−, the anion of the lactic acid) differ mainly in the arrangement of the V 2O 2 core and in mutual orientation of the VO bonds. The complexes with achiral ligands adopt the same structural type as the complexes formed from a racemic mixture of a chiral ligand, while the structure obtained using an enantiopure l, l-hydroxycarboxylate is different.