A new perspective of vanadyl-tartrate dimers. Synthesis, crystal structure, spectroscopic and magnetic properties of the chain compound: {[BaVO(C₄H₂O₆)(H₂O)₄]₂}];_n

Compound [BaVO(C₄H₂O₆)(H₂O)₄] (C₄H₂O₆ = tetrate ligand) has been synthesized and its crystal structure determined by X-ray diffraction. The compound consists of a chain structure and vanadyl-tartrate dimers and barium cations. These cations are also bound to the tartrate ligands, giving the molecular formula {[BaVO(C₄H₂O₆)(H₂O)₄]₂}_n. The vanadium atom has a penta-coodinated [VO₅] environment, while the barium atom has a nona-coordinated [BaO₉] environment. Analysis of the susceptibility data yield a practically paramagnetic behaviour for this complex down to 5 K, with a very slight increase in the χ_mT value between 5 and 2 K. The ESR spectrum shows a half-field signal characteristic of interactions between two vanadyl centres. The vanadyl dimer has shown weakly coupled exchange to give a low-lying triplet state, as can also be observed by ESR spectroscopy; the different interaction pathways have been analysed.