Dioxovanadium(V) Schiff base complexes of N-methyl-1,2-diaminoethane and 2-methyl-1,2-diaminopropane with aromatic o-hydroxyaldehydes and o-hydroxyketones: synthesis, characterisation, catalytic properties and structure

Abstract

Nineteen new dioxovanadium(V) complexes with unsymmetrical tridentate Schiff base ligands, obtained by a single condensation of 2-methyl-1,2-diaminopropane or N-methyl-1,2-diaminoethane with salicylaldehyde and its derivatives, 2-hydroxy-1-naphthaldehyde, 2-hydroxyacetophenone, 1-hydroxy-2-acetonaphthone and 2-hydroxybenzophenone, were prepared. The complexes were characterized by their 1H and 51V NMR, IR, and UV–Vis spectra. Crystal structure of the 2-(4-amino-4-methyl-2-aza-1-penten-1-yl-κ 2N)-3,5-dimethoxyphenolato-κO-dioxovanadium(V), VO 2(C 13H 19N 2O 3), has been obtained by X-ray diffraction studies. The structure revealed a rarely encountered in VO 2(tridentate Schiff base) complexes a distorted trigonal-bipyramidal coordination geometry. The complexes comprising ligands derived either from N-methyl-1,2-diaminoethane or 2-methyl-1,2-diaminopropane and 5-methoxysalicylaldehyde catalyse the oxidation of thioanisole to the corresponding sulfoxide by cumene hydroperoxide.