MONO- AND DINUCLEAR OXOVANADIUM(IV) COMPOUNDS CONTAINING VO(ONS) BASIC CORE - SYNTHESIS, STRUCTURE AND SPECTROSCOPIC PROPERTIES

摘要

Reaction of [VO(acac)(2)] with S-methyl 3-(2-hydroxyphenyl) methylenedithiocarbazate (H(2)L(1)) and its nitro- (H(2)L(2)) and bromo derivatives (H(2)L(3)) as tridentate heterodonor (ONS)(2-) ligands offers a basic VO(ONS) core. In the presence of bidentate (N,N') donor ancillary ligands, various mono- and dinuclear oxovanadium(IV) complexes [VOL(2,2'-bipy)] (1-3), [VOL(Phen)] (4, 5) and [LOV(mu-4,4'-bipy)VOL] (6-8) were obtained. The compounds have been characterized by EPR, electronic and FAB mass spectroscopic studies. The X-ray crystal structure of a representative compound [VOL(2)(2,2'-bipy)] (2) is reported and shows the presence of the tridentate ONS ligand occupying the meridional sites leading to distorted octahedral geometry. The nitrogen donor, occupying an apical position has a trans-labilizing influence, resulting in elongation of the V=O terminal bond. Magnetic susceptibility and EPR spectral studies indicate non-interacting nature (J approximate to 0) of the vanadium(IV) unpaired electrons in the dinuclear complexes (6-8). (C) 1997 Elsevier Science Ltd. [References: 59]