Thermodynamics of complex formation of 1,5,8,12-tetra-azadodecane with copper(II) ions and protons in aqueous solution

Abstract
Thermodynamic data are reported for the protonation of the tetra-amine 1,5,8,12-tetra-azadodecane (3,2,3-tet) and for the formation of the complexes Cu(3,2,3-tet)2+ and Cu(3,2,3-tet. H)3+. Data for the respective copper complexes are ΔG=–123·8 ± 0·5, –83·8 ± 0·5 kJ mol–1; ΔH(calorimetric)=–104·0 ± 0·9, –70·3 ± 1·2 kJ mol–1; ΔS= 66·3 ± 5, 45·5 ± 5 J mol–1 K–1 at 25 °C, I= 0·10M-NaCl. In comparison with related tetra-amines the sequence of basicities ([graphic omitted]log ki) is 3,3,3-tet > 3,2,3-tet > 2,3,2-tet > 2,2,2-tet and for stabilities of 1 : 1 copper(II) complexes is 3,2,3-tet > 2,2,2-tet > 3,3,3-tet.

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