Thermodynamics of complex formation in dimethyl sulphoxide. Silver(I) with quadridentate polyamines

Abstract

The changes in free energy, enthalpy, and entropy for the complex-formation reactions in dimethyl sulphoxide (DMSO) between silver(I) and tetraamines 1,4,7,10-tetraazadecane (TRIEN), tris(2-aminoethyl)amine (TREN), and 1,5,8,12-tetraazadodecane (TNENTN) have been determined by potentiometric and calorimetric measurements at 25 °C and an ionic strength of 0.1 mol dm^–3. All three amines form the very stable 1 : 1 complexes, acting as tetradentate ligands. Only TREN and TNENTN form other mono- and poly-nuclear coordinated species. Compositions and stabilities of the complexes are discussed in relation to the different structures of the ligands. From a comparison of the available experimental results on silver (I)–amino complexes in the two solvents, water and DMSO, some conclusions are made regarding the main factors determining the coordination properties in these systems.