Thermochemical parameters of complexes of di-n-propyldithiocarbamate of phosphorus-group elements

The standard molar enthalpy of formation of crystalline di-n-propyldithioca rbamate complexes of P, As, Sb and Bi(III) was determined through reaction- solution calorimetry in acetone, at 298.15 K, giving -661.10+/-5.04, -305.0 7+/-5.50, -366.62+/-1.70 and -358.98+/-1.70 kJ mol(-1), respectively. The c orresponding standard molar enthalpies of sublimation were 127.36+/-4.24, 1 45.07+/-5.30, 169.45+/-6.08 and 185.24+/-5.03 kJ mol(-1), respectively, est imated by means of differential scanning calorimetry. By combining the prec eding values with the standard molar enthalpies of formation of the chelate s in the solid phase, the standard molar enthalpies of formation in the gas phase was obtained as -533.74+/-7.28, -160.00+/-6.10, 197.17+/-6.31 and 17 3.74+/-5.31 kJ mol(-1), respectively. From the standard molar enthalpies of formation of the gaseous chelates, the homolytic values were 217.3+/-3.1, 153.0+/-3.0, 152.5+/-3.0 and 139.5+/-2.9, and the heterolytic values were 1 091.3+/-3.1, 969.2+/-3.0, 867.1+/-3.0 and 838.5+/-2.9 kJ mol(-1), and the m ean metal-sulphur bond-dissociation enthalpies were calculated. (C) 1999 El sevier Science B.V. All rights reserved.