A new coordination mode for the tartrato ligand. Synthesis of vanadium(V) oxo peroxo tartrato complexes and the X-ray crystal structure of K26$lcurlb;VO(O2)(L-tartH2)$rcurlb;2($mu;-H2O95H2O

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 prepared from aqueous-ethanolic medium and characterized by elemental analysis 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 vanadium(V) tartrate complex has been determined. The dinuclear anion exhibits two pentagonal bipyramidal polyhedra about vanadium atoms which are joined to each other by sharing two oxygen atoms of hydroxyl groups and oxygen atom from water molecule. The tartrate group is bonded to the vanadium atom in a bidentate way via oxygen atoms of neighbouring carboxylic and hydroxyl groups. The coordinated hydroxyl oxygen atom 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.