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Xiao S.-X.,Xiangnan University | Xiao S.-X.,Hunan Provincial Key Laboratory of Rare Precious Metals Compounds and Applications | Zheng X.-F.,Xiangnan University | Li W.-J.,Xiangnan University | And 9 more authors.
Journal of Thermal Analysis and Calorimetry | Year: 2015

A new ternary bismuth complex [Bi(C7H5O3)3C12H8N2] (C7H6O3, o-hydroxybenzoic acid; C12H8N2, 1,10-phenanthroline monohydrate) and its crystal were prepared and characterized. The results showed that the crystal is triclinic, space group P i¯ with a = 10.184(2) Å, b = 11.807(2) Å, c = 12.893(3) Å, α = 76.81(3)°, β = 68.79(3)°, γ = 80.85(3)°, Z = 2, Dc = 1.891 g cm-3, F(000) = 776. The crystal contains a mononuclear molecule. Bi3+ is eight-coordinated by three bidentate chelating carboxylic groups and one o-phenanthroline molecule; C7H6O3 coordinated with Bi3+ in the form of carboxylate; the two nitrogen atoms of C12H8N2 are bidentate-coordinated with Bi3+ forming a chelate ring. At 298.15 K, the standard molar enthalpy of formation of the title complex was estimated to be Δ f H m Θ [Bi(C7H5O3)3C12H8N2 (s), 298.15 K] = -(303.99 ± 4.95) kJ mol-1. © 2015 Akadémiai Kiadó, Budapest, Hungary.

Xiao S.-X.,Hunan Provincial Key Laboratory of Rare Precious Metals Compounds and Applications | Xiao S.-X.,Xiangnan University | Jiang J.-H.,Hunan Provincial Key Laboratory of Rare Precious Metals Compounds and Applications | Jiang J.-H.,Xiangnan University | And 8 more authors.
Journal of Chemical and Engineering Data | Year: 2013

This paper reports the synthesis and thermodynamic properties of three rare earth complexes, which were synthesized from praseodymium nitrate hexahydrate (Pr(NO3)3·6H2O) and heterocyclic ligands of niacin (vitamin PP, C6H5NO2) or 8-hydroxylquinoline (C9H7NO). Their compositions and structures were characterized by elemental analysis, molar conductance, thermogravimetric analysis, UV-visible spectroscopy, and IR spectroscopy. The ligand C6H5NO2 was bidentate-coordinated with Pr3+ ions through an oxygen atom of its carboxylic group which was formed by removing the proton from the hydroxyl group: the heterocyclic nitrogen atom from C9H6NO- formed a chelating ring around with Pr3+ ion. At a constant temperature of 298.15 K, the dissolution enthalpies of the reactants and products of the coordination reactions in the optimized calorimetric solvent were determined by an advanced solution-reaction isoperibol microcalorimeter. The standard molar enthalpies of the coordination reactions were determined. By combination of the experimental values of enthalpies of dissolution with some other auxiliary thermodynamic data through a designed thermochemical cycle on the basis of a supposed chemical reaction, the standard molar enthalpies of formation of the synthetic coordination complexes were estimated to be ΔfHm Θ[Pr(C6H4NO2) 2C9H6NO(s), 298.15 K] = -(1448.3 ± 2.6) kJ·mol-1, [Pr(C6H4NO3) 3·2H2O(s), 298.15 K] = -(2256.1 ± 2.9) kJ·mol-1, and [Pr(C9H6NO) 3·4H2O(s), 298.15 K] = -(1975.3 ± 4.6) kJ·mol-1. © 2013 American Chemical Society.

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