title: Thermodynamics of ligand exchange reactions between bis(dithiocarbamato)copper(II) and copper(II) salts. An EPR study.
abstract: EPR spectroscopy was chosen to investigate the ligand exchange reactions between copper(II) bis(dithiocarbamate), Cu(dtc)2, and copper(II) salts which proceeds with the formation of mixed-ligand complexes of the type Cu(dtc)X, where X = Cl, NO3, ClO4. Large concentrations of 1:1 mixed-ligand complexes of this type are obtained as indicated by the EPR spectra of acetone, CHCl3/EtOH, CHCl3/i-PrOH, CCl4/EtOH and CCl4/i-PrOH, solutions of Cu(dtc)2 and the appropriate copper(II) salt CuCl2, Cu(NO3)2 or Cu(ClO4)2. Double integration of Cu(dtc)2 EPR signals obtained at temperatures between 240 and 310 K affords the calculation of the equilibrium constant (K) of the reaction: Cu(dtc)2 + CuX2 <==> 2 Cu(dtc)X in all solvents as a function of T. From the values of K the stability constant beta of the mixed-ligand complexes has been derived. The error associated with the calculated stability constant is +/- 10%. Thermodynamic parameters (deltaH0, deltaG0 and deltaS0) are determined from the temperature dependence of K as measured by EPR spectroscopy.
authors: Department of Chemistry, University of Sofia, Bulgaria.
authors: M A
authors: MA
authors: Doicheva
authors: B G
authors: BG
authors: Jeliazkova
mesh_terms: D002627:Chemistry, Physical / Q000379:methods; D003300:Copper / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D019277:Entropy; D008024:Ligands; D008956:Models, Chemical; D012492:Salts / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics
chemical_list: D008024:Ligands; D012492:Salts; D012997:Solvents; D003300:Copper