Thermochemical Study on Coordination Complex of Samarium with Salicylic Acid and 8-Hydroxyquinoline

The coordination complex Sm(C7H5O3)2·(C9H6NO), synthesized from the reaction of samarium chloride six-hydrate with salicylic acid and 8-hydroxyquinoline, was characterized with IR, elemental analysis, molar conductance, and thermogravimatric analysis. The standard molar enthalpies of solution of [SmCl3·6H2O (s)], [2C7H6O3 (s), [C9H7NO(s)] and [Sm(C7H5O3)2·(C9H6NO)(s)] in the calorimetric solvent were determined with the solution-reaction isoperibol calorimeter at 298.15 K to be ΔsHΘm[SmCl3·6H2O (s), 298.15 K] = −103.98 ± 0.04 kJ·mol−1, ΔsHΘm [2 C7H6O3 (s), 298.15 K] = 16.35 ± 0.14 kJ·mol−1, ΔsHΘm[C9H7NO (s), 298.15 K] = −6.11 ± 0.08 kJ·mol−1 and ΔsHΘm[SmC7H5O3)2·(C9H6NO) (s), 298.15 K] = −130.08 ± 0.04 kJ·mol−1, respectively. The enthalpy was determined to be ΔrHΘm = 89.59 ± 0.18 kJ·mol−1 for the reaction SmCl3·6H2O(s) + 2C7H6O3(s) + C9H7NO(s) = Sm (C7H5O3)2·(C9H6NO) (s) + 3HCl(g) + 6H2O(1). According to the above results and the data given in literature and through Hess′ law, the standard molar enthalpy of formation of Sm(C7H5O3)2·(C9H7NO)(s) was estimated to be ΔrHΘm[Sm(C7H5O3)2·(C9H6NO)(s), 298.15 K] = −2055.9 ± 3.03 kJ·mol−1.