Synthesis, Characterization, EPR, Electrochemical, and in Situ Spectroelectrochemical Studies of Salen-Type Oxovanadium(IV) and Copper(II) Complexes Derived From 3,4-Diaminobenzophenone

Abstract

A new half unit and some new symmetrical or asymmetrical VO(IV) and Cu(II) complexes of tetradentate ONNO Schiff base ligands were synthesized The probable structures of the complexes have been proposed on the basis of elemental analyses and spectral (IR, UV-Vis, electron paramagnetic resonance, ESI-MS) data VO(IV) and Cu(II) complexes exhibit square pyramidal and square-planar geometries, respectively The complexes are non-electrolytes in dimethylformamide (DMF) and dimethylsulfoxide Electrochemical behaviors of the complexes were studied using cyclic voltammetry and square wave voltammetry Half-wave potentials (E<inf>1/2</inf>) are significantly influenced by the central metal and slightly influenced by the nature of substituents on salen While VO(IV) complexes give VOIV/VOV redox couples and a ligand-based reduction process, Cu(II) complexes give only a ligand-based reduction In situ spectroelectrochemical studies were employed to determine the spectra of electrogenerated species of the complexes and to assign the redox processes The g-values were calculated for all these complexes in polycrystalline state at 298 K and in frozen DMF (113 K) The evaluated metal-ligand bonding parameters showed strong in-plane σ-bonding for some Cu(II) complexes © 2013 Taylor & Francis.