Synthesis and characterization of dinuclear vanadium(V) oxido peroxido tartrato complexes

Vanadium(V) oxido peroxido tartrato complexes have been prepared from aqueous-ethanolic media and characterized by spectroscopic methods. Using racemic tartaric acid for the synthesis, the simultaneous crystallization of racemic compounds (racemic phases) and racemic conglomerates (chiral phases) has been observed. The X-ray crystal structure of (NH 4 ) 4 [V 2 O 2 (O 2 ) 2 ((2R,3R)–H 2 tart) 2 (μ–H 2 O)][V 2 O 2 (O 2 ) 2 ((2S,3S)–H 2 tart) 2 (μ–H 2 O)]·8H 2 O (tart = C 4 H 2 O 6 4− ) revealed that the dinuclear anion is composed of two pentagonal bipyramidal polyhedra about vanadium atoms, which are joined to each other by sharing two oxygen atoms of hydroxyl groups and an oxygen atom from a bridging water ligand. The prepared compounds are not stable in aqueous solution; 51 V NMR spectra exhibit the signals of several peroxido and non-peroxido vanadium(V) complexes.