A NEW COORDINATION MODE FOR THE TARTRATO LIGAND - SYNTHESIS OF VANADIUM(V) OXO PEROXO TARTRATO COMPLEXES AND THE X-RAY CRYSTAL-STRUCTURE OFK-2[(VO(O-2)(L-TARTH(2)))(2)(MU-H2O)].5H(2)O

Vanadium(V) oxo peroxo tartrate complexes M-2[{VO(O-2)(L-tartH(2))}(2) (mu-H2O)]. 5H(2)O (M = K+, NH4+; tart(4-) = C4O6H24-) have been prepar ed from aqueous-ethanolic medium and characterized by elemental analys is and IR spectroscopy. The X-ray crystal structure of K-2[{VO(O-2) (L -tartH(2))}(2)(mu-H2O)]. 5H(2)O, as the first crystal structure of a v anadium(V) tartrate complex has been determined. The dinuclear anion e xhibits two pentagonal bipyramidal polyhedra about vanadium atoms whic h are joined to each other by sharing two oxygen atoms of hydroxyl gro ups and oxygen atom from water molecule. The tartrate group is bonded to the vanadium atom in a bidentate way via oxygen atoms of neighbouri ng carboxylic and hydroxyl groups. The coordinated hydroxyl oxygen ato m is bonded also to the second vanadium atom, but in a monodentate way . This type of bonding of tartrate group was not observed so far. (C) 1998 Elsevier Science Ltd. All rights reserved.