Affinity of Tripodal and Linear Tetraamines for Silver(I) in Dimethylsulfoxide

The thermodynamic functions of the complexation of Ag(I) by the tripodal ligands, tris(2-(methylamino)ethyl)amine (Me(3)tren) and tris(2-(dimethylamino)ethyl)amine (Me(6)tren) (L), are determined in dimethyl sulfoxide (DMSO) by potentiometric and calorimetric techniques at 298.0 K and 0.1 mol.dm(-3) ionic strength (Et4NClO4). A comparison is made between previous data concerning Ag(I) complex formation with the non-alkylated tripodal 2,2',2 ''-triaminotriethylamine (tren), in order to analyze the influence of N-methylation on this type of branched donor, and with those relative to the linear triethylenetetramine (trien) and 1,1,4,7,10,10-hexamethyltriethylenetetramine (Me(6)trien). The results are discussed taking into account different sigma-donating properties, geometric arrangement of the ligands, steric repulsions and solvation effects.