Mixed-ligand oxovanadium(V) complexes incorporating bidentate salicylaldehyde and tridentate aldimine ligands

Abstract

Mixed-ligand oxovanadium(V) complexes, [VVO(L)-(sal)], containing salicylaldimine ligands of α-amino acids H2L [(1);R = Me, i-Pr and CH2Ph] and salicylaldehyde (Hsal) have been synthesized. The coordination sphere of the complexes is of the VO(ONO)(OO) type, where O atoms are phenolic, carboxylic and aldehydic, and N is of the azomethine type. The complexes are diamagnetic and exhibit only one LMCT band at ca. 490 nm. They display quasi-reversible one-electron reduction peaks in a CH2Cl2-MeCN (2∶1v/v) mixture in the 0.07–0.13V versus s.c.e. range. A trend in the redox potential data has been rationalized on the basis of conventional normal substituent effects.