Chemistry Department, Payame Noor University, 19395-4697 Tehran, Iran.
The therrmodynamic parameters and equilibrium constant of displacement of dimethy sulfide by 3-carboaldehyde pyridine as N-donor ligand in cis-[Pt(4-MeC6H4)2(SMe2)2] complex have been measured using UV vis spectroscopy in acetone, dichloromethane and benzene at various temperatures (T=15-20 °C) and compared with previous my reported about similar reaction. ΔHo (KJ.mol-1) of the mentioned reaction in acetone has been 7.158 while obtained less in dichloromethane (4.109 ) and more in benzene(9.96). The entropy of the reaction has been obtained 86.86 J.mol-1.K-1 in acetone , while calculated less in CH2Cl2 (73.29 J.mol-1.K-1) and more in last solvent (97.40 J.mol-1.K-1). Also, the Gibbs energy, ΔG (J.mol-1), of the reaction obtained -18738.79, -17741.55 and -19043.06 respectively, with the same order. In all three solvents, the values of enthalpy and entropy change have been positive and decreased as the donor number of the solvents decreased.