Calorimetric study of ethyleneurea, ethylenethiourea and propyleneurea cadmium chloride adducts

Adducts of the general formula CdCl2. nL [n = 1 and 2; L = ethyleneurea (eu ), ethylenethiourea (etu) and propyleneurea (pu)] were synthesized by a sol id state route and characterized by elemental analysis, infrared spectrosco py, and reaction solution calorimetry. The infrared results showed that eu and pu coordinate through carbonylic oxygen atoms, whereas etu uses the nit rogen as coordinating site. The standard molar reaction enthalpy in condens ed phase: CdCl2(c) + nL(c) = CdCl2. nL(c); Delta H-r(m)0, were obtained fro m reaction-solution calorimetry, to give the following values for mono and bisadducts: -20.0 +/- 0.1; -19.9 +/- 0.1; -13.3 +/- 0.1 and -38.6 +/- 0.1; -56.9 +/- 0.1; -17.0 +/- 0.1 kJ mol(-1) for eu, etu and pu, respectively. T he values of decomposition (Delta H-D(m)theta) and lattice enthalpy (Delta H-M(m)theta) as well as the mean cadmium-ligand bond dissociation enthalpy, D (Cd-L), were calculated for all adducts. (C) 2001 Elsevier Science B.V. All rights reserved.