Synthesis, ESR, UV-Visible and reactivity studies of new bis(N-dimethoxyaniline-3,5-Bu-t(2)-salicylaldiminato)copper(II) complexes

Abstract

Several new copper(II) complexes (4-6) with N-dimethoxyphenyl-3,5-Bu-t(2)-salicylaldimine ligands abbreviated as N-R-3,5-DTBS, where R = 2,4-dimethoxyphenyl (1), 2,5-dimethoxyphenyl (2) and 3,5-dimethoxyphenyl (3) have been prepared and their spectroscopic (IR, H-1 NMR, UV/Vis, ESR), magnetic and redox reactivity are described. The ESR spectra of frozen-solution 4-6 and solid state 4 and 5 are indicative of axially symmetric g-tensor (g(parallel to) > g(perpendicular to) > 2.03). The powder ESR spectrum of 6 is unusual for CuN2O2 type systems and exhibits "reversed" type (g(parallel to) < g(perpendicular to)) signal with a rhombic g-tensor g(3) (2.235) > g(2) (2.128) > g(1) (2.019) pattern indicative of a d(z)(2) state. Chemical oxidation of 4 and 6, as supported by ESR and UV/Vis techniques, generates new Cu(II) species and Cu(II)-phenoxyl radicals. The CV studies have shown that the complexes possess ligand-centered and copper(II)-centered quasi-reversible and irreversible responses. (C) 2012 Elsevier B.V. All rights reserved.