Flow microcalorimetry in stepwise equilibriums of metal complexes. Reactions of N,N'- and N,N-diethylethylenediamine with hydrogen and copper(II) ions

Enthalpy values assocd. with the stepwise reactions of H+ and Cu2+ with N,N'-diethylethylenediamine [111-74-0] and N,N-diethylethylenediamine [100-36-7] were detd. by flow microcalorimetry at 25° and 0.5M (NaClO4) ionic strength. Combination with reported free energy values gave appropriate entropy values. Comparison with results for ethylenediamine shows that Et substitution causes a decrease in exothermicity of protonation and complexation and leads to a larger entropy change. Generally, reactions with the sym. ligand are more exothermic than those with the asym. one.