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Electrochemical and Structural Characterization of Tri‐ and Dithioether Copper Complexes

2010; Wiley; Volume: 2011; Issue: 2 Linguagem: Inglês

10.1002/ejic.201000960

1099-0682

Paulina R. Martínez‐Alanis, Víctor M. Ugalde‐Saldívar, Iván Castillo,

Metal-Catalyzed Oxygenation Mechanisms

Abstract Tri‐ and dithioethers tris(2‐ tert ‐butyl‐4‐methylphenylthiomethyl)amine ( 1 ), bis(2,4‐dimethylphenylthio)methane ( 2 ), and bis(2‐ tert ‐butyl‐4‐methylphenylthio)methane ( 3 ) were developed to evaluate their coordination properties toward Cu + . The thioethers associate weakly with Cu + when ClO 4 – or PF 6 – are the counterions, while the reactions with CuI afford crystalline products in the case of nitrilotrithioether 1 and dithioether 2 . The solid‐state structures of the complexes [( 1 )CuI] 2 and [( 2 )(CuI) 4 (CH 3 CN) 2 ] 2 · 2THF · 4CH 3 CN are characterized by the chelating‐bidentate coordination mode of 1 and the bridging nature of 2 spanning two Cu 4 I 4 cuboidal clusters. Electrochemical studies of the thioether/Cu + complexes revealed that the sulfur‐rich coordination environment results in high redox potentials for the Cu 2+ /Cu + couple, which is close to the first oxidation potential of the ligands. Thus, chemical (Cu 2+ ) or electrochemical oxidation of the thioethers resulted in oxidative decomposition of the ligands with concomitant reduction to Cu + , in agreement with the electrochemical results. Bulk electrolyses of the tri‐ and dithioethers 1 – 3 enabled us to confirm that the corresponding disulfides are the major oxidation products. The cathodic peak potentials for the Cu + /Cu 0 couple of the complexes allowed us to determine the relative stability of the thioether/Cu + complexes.