Stereochemical and electronic control of the copper(II)/(I) couple by N2S4-donor macrocycles

Abstract

The N₂S₄ donor complex [Cu(L¹)]²⁺(L¹= 1,4,10,13-tetrathia-7,16-diazacyclo-octadecane) shows a chemically reversible copper (II)/(I) couple at E_½–0.31 V vs. Fc/Fc⁺(ferrocene/ferrocenium), whereas the methylated analogue, [Cu(L²)]²⁺(L²= 7,16-dimethyl-1,4,10,13-tetrathia-7,16-diazacyclo-octadecane) shows a more anodic copper(II)/(I) couple at E_½+ 0.06 V vs. Fc/Fc^+˙; these differences in redox potential can be related to the stereochemical features of the copper(II) complexes, the crystal structures of which have been determined for [Cu(L¹)]²⁺ and [Cu₂(L²)(NCMe)₂]²⁺.