Stereospecific formation of alpha-hydroxycarboxylato oxo peroxo complexes of vanadium(V). Crystal structure of (NBu4)(2)[V2O2(O-2)(2)-(L-lact)(2)]center dot 2H(2)O and (NBu4)(2)[V2O2(O-2)(2)(D-lact) (L-lact)]center dot 2H(2)O

An overview of structurally characterized alpha-hydroxycarboxylatodioxo- an d alpha-hydroxycarboxylatooxoperoxovanadates( is presented and the geometri c parameters of the V2O2 bridging core are discussed. The first case of a s tereospecific formation of oxoperoxovanadates(V) is reported: The crystal s tructures of the isomeric compounds (NBu4)(2)[V2O2(O-2)(2)(L-lact)(2)]. 2H( 2)O and (NBu4)(2)[V2O2(O-2)(2)(D-lact)(L-lact)] . 2H(2)O (lact = C3H4O32-, the anion of the lactic acid) differ mainly in the arrangement of the V2O2 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 race mic mixture of a chiral ligand, while the structure obtained using an enant iopure L,L-hydroxycarboxylate is different. (C) 2000 Elsevier Science Inc. All rights reserved.