Synthesis, spectroscopic properties, structural characterization and electrochemistry of mixed ligand complexes of copper(I) halide with PPh3 and naphthylazoimidazole

The reaction of CuX (X = Cl, Br, I) with a mixture of PPh3 and 1-alky1-2-(naphthyl-alpha/beta-zo) imidazole has synthesized mixed ligand complexes of the composition, [Cu(alpha/beta-NaiR)(PPh3)X]. The spectroscopic characterization(IR, UV-Vis, H-1 NMR) supports this formulation. The single crystal X-ray diffraction study of [Cu((alpha-NaiMe)(PPh3)1] (7a) (alpha-NaiMe = 1-methyl-2-(naphthyl-alpha-azo)imidazole) shows a distorted tetrahedral geometry about Cu(I). Cyclic voltammograms of the complexes show a high potential Cu(II)/Cu(I) couple and azo reductions. The [Cu(alpha/beta-NaiR)(PPh3)1] complexes show an additional oxidative response at 0.4 V that is assigned to I/I- A sharp anodic peak at similar to-0.2 V is assigned to the oxidation of metallic Cu, deposited on electrode surface upon scanning to the negative side of the SCE. DFT and TD-DFT computations of [Cu((ct-NaiMe)(PPh3)I] (7a), [Cu((alpha-NaiMe)(PPh3)1](+) (7a(+)) and [Cu((alpha-NaiMe)(PPh3)1](-) (7a(-)) were carried out to examine the electronic configuration and to explain the spectral and redox properties of the complexes. (C) 2010 Elsevier Ltd. All rights reserved.