Enthalpies of dissolution of cobalt(II) and copper(H) acetylacetonates in organic solvents

Data on enthalpy changes in dissolution of cobalt(II) and copper(II) acetylacetonates (Co(Acac)(2) and Cu(Acac)(2)) in chloroform, DMF, and pyridine were obtained by calorimetric measurements at 298.15 K. The enthalpies of transfer of Co(Acac)(2) and Cu(Acac)(2) from chloroform to DMF and pyridine were calculated. It was demonstrated with our and literature data that the exothermic dissolution of the salts in DMF and pyridine is due to additional coordination of electron-donating solvent molecules by the metal ion. The thermodynamic stability of solvate complexes was found to substantially depend on the nature of both the complexing metal and the solvent; the strongest specific solvation interactions were noted for Cu(Acac)(2) in DMF and Co(Acac)(2) in pyridine.