THERMOCHEMICAL FEATURES OF COMPLEXES OF THIOACETAMIDE AND THIOUREA WITH ANTIMONY AND BISMUTH TRIIODIDES

Complexes of the type MI(3).nL [where M is Sb and Bi, L is thiourea (TU) or thioacetamide (TA)] were prepared and characterized by their melting interval, elemental analyses, thermogravimetry, IR spectroscopy and mass spectra. The solution-reaction was used to determine the enthalpy of formation at 298.15 K of crystalline SbI3.2TU - 291.3, SbI3.2TA - 258.8, BiI3.2TU - 340.8, and BiI3.TA - 233.1 kJ mol(-1). The standard enthalpies of decomposition of the complexes, as well as the lattice standard enthalpies and the standard enthalpies of the Lewis acid/base reactions in the gaseous phase were calculated through adequate thermochemical cycles. The standard mean element-sulphur bend enthalpies were estimated as 101.1 and 113.2 kJ mol(-1) for SbI3.2TA and SbI3.2TU and 146.5 and 129.3 kJ mol(-1) for BiI3.TA and BiI3.2TU, respectively.