Free energy, enthalpy, and entropy of formation for copper(II) complexes with some C(1)-substituted 1,2-diaminoethanes

Abstract

The concentration quotients have been determined by pH measurement for the copper(II) complexes of 1-methyl-, 1-ethyl-, 1-phenyl- and 1,1-dimethyl-substituted 1,2-diaminoethane in aqueous NaClO₄–Ba(ClO₄)₂ media over the ionic-strength range 0·04–0·20M at 25°. Thermodynamic formation constants were obtained by extrapolation of the quotients to zero ionic strength. The corresponding enthalpy changes were measured calorimetrically (except for 1,2-diamino-1-phenylethane). Free energy, enthalpy, and entropy changes for formation of the 1:1 and 1:2 complexes are reported.