Synthesis, characterization and standard molar enthalpy of formation of La(C7H5O3)2·(C9H6NO)

The product from reaction of lanthanum chloride seven-hydrate with salicylic acid and 8-hydroxyquinoline, La(C7H5O3)2·(C9H6NO), was characterized by IR, elemental analysis, molar conductance, and thermogravimetric analysis. The standard molar enthalpies of solution of [LaCl3·7H2O (s)], [2C7H6O3 (s)], [C9H7NO (s)] and [La(C7H5O3)2·(C9H6NO) (s)] in a mixed solvent of absolute ethyl alcohol, dimethyl formamide (DMF) and perchloric acid were determined by calorimetry to be ΔsHmΘ[LaCl3·7H2O (s), 298.15 K] = −96.45 ± 0.18 kJ mol−1, ΔsHmΘ[2C7H6O3 (s), 298.15 K] = 14.99 ± 0.17 kJ mol−1, ΔsHmΘ[C9H7NO (s), 298.15 K] = −3.86 ± 0.06 kJ mol−1 and ΔsHmΘ[La(C7H5O3)2·(C9H6NO) (s), 298.15 K] = −117.78 ± 0.11 kJ mol−1. The enthalpy change of the reactionequation(1)LaCl3·7H2O (s) + 2C7H6O3 (s) + C9H7NO (s) = La (C7H5O3)2·(C9H6NO) (s) + 3HCl (g) + 7H2O (l)was determined to be ΔrHmΘ = 91.57 ± 0.34 kJ mol−1. From data in the literature, through Hess’ law, the standard molar enthalpy of formation of La(C7H5O3)2·(C9H7NO) (s) was estimated to be ΔfHmΘ[La(C7H5O3)2·(C9H6NO) (s), 298.15 K] = − 2076.5 ± 3.9 kJ mol−1.