Xiao, SX; Jiang, JH; Li, Xu; Li, C; Zhang, Hui; Yao, F; Li, You; Li, Q
The product, [Pr(C7H5O3)(2)(C9H6NO)], which was formed by praseodymium nitrate hexahydrate, salicylic acid ( C7H6O3), and 8-hydroxyquinoline ( C9H7NO), was synthesized and characterized by elemental analysis, UV spectra, IR spectra, molar conductance, and thermogravimetric analysis. In an optimalizing calorimetric solvent, the dissolution enthalpies of [ Pr( NO3)(3)center dot 6H(2)O( s)], [ 2 C7H6O3( s) ? C9H7NO( s)], [ Pr( C7H5O3) 2( C9H6NO)( s)], and [ solution D ( aq)] were measured to be, by means of a solution-reaction isoperibol microcalorimeter, Delta H-s(m)theta[Pr(NO3)(3)center dot 6H(2)O(s), 298.15 K] = -(20.66 +/- 0.29) kJ mol(-1), Delta H-s(m)theta[2C(7)H(6)O(3)(s) + C9H7NO(s), 298.15 K] = (42.27 +/- 0.31) kJ mol(-1), Delta H-s(m)theta [solution D (aq), 298.15 K] = -(89.15 +/- 0.43) kJ mol(-1), and Delta H-s(m)theta{Pr(C7H5O3)(2)(C9H6NO)] (s), 298.15 K} = -(41.04 +/- 0.33) kJ mol(-1), respectively. Through an improved thermochemical cycle, the enthalpy change of the designed coordination reaction was calculated to be Delta H-r(m)theta = (213.18 +/- 0.69) kJ mol(-1), the standard molar enthalpy of the formation was determined as Delta H-f(m)theta{Pr(C7H5O3)(2)(C9H6NO)] (s), 298.15 K} = -(1875.4 +/- 3.1) kJ mol(-1).