Synthesis, spectroscopic and redox properties of the copper(II) complexes of N-(di-methylphenyl)-3,5-Bu-2(t)-salicylaldimines

Abstract

A series of copper(II) complexes (CuL2x) with new N-di-methylphenyl-3,5-Bu'(2)-salicylaldimines ((LH)-H-x) were prepared and characterized by IR, UV/vis, H-1 NMR, ESR, cyclic voltammetry techniques and chemical oxidation. (LH)-H-x ligands have been found selectively bind to a Cu-II, rather than to Ni-II, Co-II, Mn-II, VOIV, Zn-II and C-II. ESR examinations of the CuL2x complexes demonstrate that they exist in magnetically diluted mononuclear or coupled triplet-state structures in the solid. The temperature dependent (113-283 K) intensity of the powder ESR spectra for some Cu-2(x) is characteristic of ferromagnetic coupling (J > 0). The reduction potentials of CuL2x in DMSO are sensitive to aniline moieties. Chemical oxidation of CuL2x with (NH4)(2)[Ce(NO3)(6)] in CHCl3 and MeCN solutions at 300 K affords gradually disappearance of their ESR signals and dramatic changes in the electronic spectra as well as the appearance of new maximum bands at 530-672 (CHCl3) and 670-700nm (MeCN), suggesting generation of Cu-II-phenoxyl radical species. (c) 2005 Elsevier B.V. All rights reserved.