Thermodynamic and spectroscopic properties of mixed complexes in aqueous solution. Copper(II) complexes of 2,2′-bipyridyl and cyclo-alkane-1,1-dicarboxylic acids

Abstract

The heats of formation. of mixed complexes of copper(II) with 2,2′-bipyridy and cyclopropane-, cyclobutane-, cyclopentane-, and cyclohexane-1, 1-dicarboxylic acids have been determined calorimetrically at 25 °C in 0.1 mol dm^–3 sodium perchlorate, and have been used to calculate the relative enthalpies. The heats of reaction of Cu^II with the acids have also been measured under the same conditions. From the thermodynamic data the relative importance of enthalpy and entropy terms in stabilising mixed complexes is assessed. By assuming the enthalpy of copper(II) complex formation to be related to the strength of the co-ordinate bonds, the e.s.r. and electronic spectral parameters found for aqueous solutions of the complexes have been interpreted and their significance discussed together with that of the thermodynamic values.