Thermodynamic and spectroscopic studies on the complexation of silver(I) by 2-(diphenylphosphino)pyridine in dimethyl sulfoxide and propylene carbonate

The thermodynamic parameters for the Ag(I) complexation with the mixed, sho rt-bite P-N ligand 2-(diphenylphosphino)pyridine (Ph(2)Ppy) in dimethyl sul foxide (dmso) and propylene carbonate (4-methyl-1,3-dioxolan-2-one, pc) hav e been determined by potentiometric and calorimetric techniques at 298 K an d 0.1 mol dm(-3) ionic strength (NEt4ClO4). Mononuclear complexes are forme d both in dmso (AgLj+, j = 1-3) and in pc (AgLj+, j = 2, 3) where the ligan ds act as P donors. In pc, Ag2L2+, Ag2L22+ and Ag2L32+ dinuclear species ar e also formed in which the ligands are bridging in behavior. All the comple xes are enthalpy stabilized whereas the entropy changes counteract the comp lex formation. P-31 NMR and FT IR studies have also been performed to obtai n some additional information on the coordination mode of the species forme d. The results are discussed in terms of the steric requirements of the spe cies and of the different physicochemical properties of the two solvents. ( C) 2000 Elsevier Science S.A. All rights reserved.