Gavin R. Hedwig

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

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.

Thermodynamic study on oxime complexes: the relative co-ordinating power of ketone, oxime, and amine functional groups

Thermodynamic data (ΔG, ΔH, ΔS) are reported for the reaction of the diamine-dioxime 4,4,9,9-tetramethyl-5,8-diazadodecane-2,11-dione dioxime with protons and copper(II) ions in aqueous solution. Data for the formation of the copper complexes are compared with data for the analogous diamine-diketone 4,4,9,9-tetramethyl-5,8-diazadodecane-2,11-dione and the analogous tetra-amine 2,11-diamino-4,4,9,9-tetramethyl-5,8-diazadodecane. The relative co-ordinating powers of different donor groups in these structurally related ligands are amine > oximato ∼ oxime > ketone (∼H2O).

Complex formation with a C-alkyl-substituted linear tetra-amine. Free energy, enthalpy, and entropy changes for the reactions of 4,4,9,9-tetramethyl-5,8-diazadodecane-2,11-diamine with copper(II) ions and protons in aqueous solution

Thermodynamic data are reported for the protonation of the hexamethyl-substituted tetra-amine 4,4,9,9-tetra-methyl-5,8-diazadodecane-2,11-diamine (hm-3,2,3-tet) and for the formation of the copper complex Cu(hm-3,2,3-tet)2+. Data are compared with those for the unsubstituted tetra-amine, 3,2,3-tet; small differences in stepwise protonation constants and in copper complex stabilities relate mainly to differences in ΔS values.

A reinvestigation of the enthalpy changes for the interaction of the sulphate ion with some transition-metal ions in aqueous solution

Calorimetric enthalpy data are reported for the interaction of the sulphate ion with divalent Mg, Mn, Co, Cu, and Zn ions in aqueous solution. Data are compared with those from other calorimetric and ‘temperature coefficient’ studies. The small dependence of ΔH° on the accuracy of log K° and the significant dependence of ΔH° on the choice of mean activity-coefficient expression are discussed. The chosen activity-coefficient expression contributes significantly to the computed solution compositions and to the correction of enthalpy data to infinite dilution; it is mainly these factors which give rise to the variance between reported calorimetric results.