STANDARD ENTHALPY OF FORMATION OF DI-ISOBUTYLDITHIOCARBAMATE COMPLEXES OF ZINC-GROUP ELEMENTS AND MEAN M-S BOND-DISSOCIATION ENTHALPIES

The standard enthalpies of formation of crystalline di-isobutyldithioc arbamate complexes of Zn, Cd and Hg(II) have been derived by solution calorimetry at 298.15 K, giving values -526.06 +/- 3.30, -468.07 +/- 3 .23 and -310.15 +/- 3.56 kJ mol-1, respectively. The corresponding mol ar enthalpies of sublimation, 283 +/- 2, 281 +/- 2 and 247 +/- 1 kJ mo l-1, were estimated by means of differential scanning calorimetry. Fro m the standard molar enthalpies of formation of the gaseous chelates, -243 +/- 4, - 187 +/- 4 and -63 +/- 4 kJ mol-1, the homolytic 137 +/- 4, 118 +/- 4 and 75 +/- 4 kJ mol-1 and heterolytic 700 +/- 4, 646 +/- 4 and 682 +/- 4 kJ mol-1 mean metal-sulphur bond enthalpies were calcu lated. The homolytic enthalpies decrease from zinc to mercury and depe nd on the nature of the radical attached to the nitrogen of the ligand .