Synthesis and Characterisation of Some Vanadium(V) and (IV) Compounds with Benzaldoxime

Abstract

Abstract The interaction of an ethanolic solution of benzaldoxime, C6H5–CH˭NOH (HL), with aqueous solutions of V(V) or V(IV) has been studied. These reactions lead to the formation of a series of compounds: (1) a green decavanadate salt of the formula H4Na2V10O27(OH) · 6H2O; (2) a yellow‐green dimeric coordination complex of the formula V2O3(OH)(L*)2(HL)2 in which L* is the deprotonated species of the oxidized form of benzaldoxime, (C6H5C(H−)NO2); and (3) a green monomeric complex of the formula [VO(H2O)2(L)2] · 2H2O in which L is the deprotonated form of benzaldoxime, (C6H5–CH˭NO−). Elemental analyses, conductometry, infrared spectroscopy, UV‐Visible spectrometry, nuclear magnetic resonance (NMR), electronic paramagnetic resonance (ESR), and mass spectroscopy have been used to elucidate the structures of the resultant compounds. Magnetic measurements, ESR spectroscopy, and UV‐Visible spectrometry have shown the existence of a lower oxidation state of vanadium in some of these compounds. The reduction of V(V) to V(IV) was due to a ligand–metal redox reaction.