The product from reaction of samarium chloride hexahydrate with salicylic acid and Thioproline, [Sm(C7H5O3)2·(C4H6NO2S)]·2H2O, was synthesized and characterized by IR, elemental analysis, molar conductance, and thermogravimetric analysis. The standard
molar enthalpies of solution of [SmCl3·6H2O(s)], [2C7H6O3(s)], [C4H7NO2S(s)] and [Sm(C7H5O3)2·(C4H7NO2S)·H2O(s)] in a mixed solvent of absolute ethyl alcohol, dimethyl sulfoxide(DMSO) and 3 mol L−1 HCl were determined by calorimetry to be ΔsHmΦ[SmCl3 δ6H2O (s), 298.15 K]= −46.68±0.15 kJ mol−1 ΔsHmΦ[2C7H6O3 (s), 298.15 K]= 25.19±0.02 kJ mol−1, ΔsHmΦ[C4H7NO2S (s), 298.15 K]=16.20±0.17 kJ mol−1 and ΔsHmΦ[Sm(C7H5O3)2·(C4H6NO2S)]·2H2O (s), 298.15 K]= −81.24±0.67 kJ mol−1. The enthalpy change of the reaction ((1))