Reactions of metal β-diketonates. : IV. Reactions of bis(acetylacetonato)oxovanadium(IV) hydrate, VO(acac) 2H 2O, with chelating ligands

Abstract

The reactions of bis(acetylacetonato)oxovanadium (IV) hydrate, VO(acac) 2H 2O, with different chelating ligands (containing at least one NH 2 group) have been studied. In dry refluxing toluene, heterochelates of the type [VO(acac)(Lsbnd;L)] 0(or+)·nH 2O (where LL = neutral or monoanion of bidentate chelating ligands; n = 0–1) have been isolated. On the other hand, dibasic tridentate (LH 2) or dibasic tetradentate (L′H 2) Schiff bases replaced all the acetylacetonate anions from VO(acac) 2H 2O to produce VO(L)H 2O or VO(L′) in refluxing toluene or ethanol. Analogous reactions of VO(acac) 2H 2O with aminoacids, aminoalcohols, semi- and thiosemi-carbazide in ethanol, methanol, water-ethanol or water-acetone mixture, produced a variety of mixed ligand complexes of oxovanadium(IV) ion involving Schiff bases, many of which show subnormal magnetic moments at room temperature. In the course of this study several mixed ligand oxovanadium(IV) complexes with neutral acetylacetone (or glycine) have also been isolated. The reactions of VO(acac) 2H 2O with chelating amino ligands in presence of even trace amount of water invariably result in the template syntheses of Schiff base chelates, which has been discussed qualitatively The electronic spectra of these chelates have been interpreted with the help of either C 2V or C 4V local symmetry. The elemental analyses, i.r. spectral data and cryomagnetic data have also been used to characterise the complexes.