Synthesis, Spectroscopic and Redox Properties of the Copper(II) Complexes of N-(di-methylphenyl)-3,5-Bu2t-salicylaldimines

Abstract

A series of copper(II) complexes (CuL2x) with new N-di-methylphenyl-3,5-Bu2t-salicylaldimines (LxH) were prepared and characterized by IR, UV/vis, 1H NMR, ESR, cyclic voltammetry techniques and chemical oxidation. LxH ligands have been found selectively bind to a CuII, rather than to NiII, Co II, MnII, VOIV, ZnII and Cd 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 CuL2x is characteristic of ferromagnetic coupling (J > 0). The reduction potentials of CuL2x in DMSO are sensitive to aniline moieties. Chemical oxidation of CuL2x with (NH<inf>4</inf>)<inf>2</inf>[Ce(NO <inf>3</inf>)<inf>6</inf>] in CHCl<inf>3</inf> 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 (CHCl<inf>3</inf>) and 670-700 nm (MeCN), suggesting generation of CuII-phenoxyl radical species. © 2005 Elsevier B.V. All rights reserved.