A NEW PERSPECTIVE ON VANADYL TARTRATE DIMERS .2. STRUCTURE AND SPECTROSCOPIC PROPERTIES OF CALCIUM VANADYL TARTRATE TETRAHYDRATE

The calcium vanadyl tartrate complex [Ca(VO)(d,l-C4H2O6)(H2O)(4)] has been synthesized and characterized by spectroscopic methods. Its crystal structure was solved by X-ray methods. The compound is monoclinic, space group P2(1)/c, with a-8.0282(5), b=17.1568(8), c=7.6113(3)Angstrom, beta=94.269(4)degrees and Z = 4. The structure consists of centrosymmetric vanadyl tartrate dimers, [(VO)(d,l-C4H2O6)](4-)(2), and calcium cations placed between them. As a result, dimers form chains in the [101] direction. Neighbouring chains are linked by the coordination of the calcium ion to the oxygen atom of a vanadyl group of a different chain, thus forming a two-dimensional structure. Different layers are linked by hydrogen bonds. Spectroscopic studies show the existence of intra-dimeric interactions between vanadium atoms.