Mean phosphorus– and arsenic–sulphur bond enthalpies in diethyldithiocarbamate chelate complexes

Abstract

The standard enthalpies of formation at 298.15 K of crystalline tris(diethyldithiocarbamate) compounds of P and As were determined by solution-reaction calorimetry, giving –304.5 ± 7.6 and –104.5 ± 7.6 kJ mol^–1 respectively. The enthalpies of sublimation, 143 ± 2 and 124 ± 3 kJ mol^–1, respectively, were estimated. From these values, the enthalpies of formation of both compounds in the gaseous phase were derived. The homolytic and heterolytic phosphorus– and arsenic–sulphur bond-enthalpy parameters were calculated. The larger values for phosphorus are interpreted as the result of a better overlap of the d orbitals of the atoms involved.