Electrochemical studies of dinuclear copper(I) complexes with ligands having N<SUB>2</SUB>P<SUB>4</SUB> and N<SUB>2</SUB>As<SUB>4</SUB> donor sites: generation of Cu<SUP>II</SUP>-Cu<SUP>I</SUP> mixed valence species

The cyclic voltammetric behaviour of a series of dinuclear copper(I) complexes with the ligands BDPE, BDAE and BDPX [where BDPE = α,α'-bis(bis(2-(diphenylphosphino)ethyl)amino)ethane, BDAE = α,α'-bis(bis(2-(diphenylarsino)ethyl)amino)ethane and BDPX = α,α'-bis(bis(2-diphenylphosphino)ethyl)amino)m-xylene] were studied in DMF. The dinuclear complexes show two quasi-reversible one-electron oxidation-reduction couples in the ranges +0.58 to +0.95 V and +0.92 to +1.32 V. The observations were interpreted as a stepwise two-electron oxidation that generated CuII-CuI mixed valence species as an intermediate. The stability of the mixed valence species thus formed was calculated in terms of a conproportionation constant (Kcon) and the results discussed