Synthesis, Characterization, and Thermochemical Study on a Ternary Complex [Sm(m-MOBA)3phen]2

et al. 2012

Ind. Eng. Chem. Res.

This article reports the synthesis and thermodynamic properties of a novel rare earth coordination complex, samarium chloride hexahydrate (SmCl3·6H2O) with nicotinic acid (C6H5NO2) and 8-hydroxylquinoline (C9H7NO), whose composition and structure were characterized by elemental analysis, molar conductance, thermogravimetric analysis (TG–DTG), UV spectroscopy, IR spectroscopy, and X-ray powder diffraction. During the process of coordination, C6H5NO2 was bidentate-coordinated with the rare earth ion (Sm3+) through an acidic group that was formed by removing the proton; the hydroxyl oxygen atom and heterocyclic nitrogen atom of C9H6NO– formed a chelate ring with Sm3+ for coordination. The X-ray powder diffraction pattern demonstrated that the crystal type of [Sm(C6H4NO2)2·C9H6NO] is similar to that of C5H11NO2, with the cell parameters a = 5.426 nm, b = 22.105 nm, and c = 5.277 nm. At a constant temperature of 298.15 K, the dissolution enthalpies of the reactants and products of the coordination reaction in the optimized calorimetric solvent were determined with an advanced solution–reaction isoperibol microcalorimeter. The standard molar enthalpy change of the coordination reaction was determined to be Δr H m Θ = (167.49 ± 0.39) kJ·mol–1. The standard molar enthalpy of formation of the title complex, [Sm(C6H4NO2)2·C9H6NO], was estimated to be Δf H m Θ[Sm(C6H4NO2)2·C9H6NO(s), 298.15 K] = −(1483.4 ± 2.4) kJ·mol–1, from a combination of the experimental values of enthalpies of dissolution and some other auxiliary thermodynamic data through a designed thermochemical cycle based on a supposed chemical reaction.

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Thermodynamic Properties of the Rare Earth Coordination Complex [Sm(C₆H₄NO₂)₂·C₉H₆NO]

et al. 2012

Ind. Eng. Chem. Res.

“…The characteristic peaks of Phen can be found in the spectra of complexes and confirmed after compared with homoleptic complexes of RE III and HL. There are shifts for ν(C=C) from 1618 cm –1 (free ligand) to about 1600–1608 cm –1 (complexes), and δ(C–H) from 733 cm –1 (free ligand) to 730–731 cm –1 (complexes), which indicates that the Phen ligand coordinates with rare earth ions through nitrogen atoms 8. The new peaks of RE –N (544 cm –1 ) and RE –O (418 cm –1 ) in the spectra of the complexes further proved the coordination of Phen and HL with RE III 9.…”

Section: Resultsmentioning

confidence: 99%

Three Ternary Rare Earth(III) Complexes Based on 3‐[(4,6‐Dimethyl‐2‐pyrimidinyl)thio]‐propanoic Acid and 1,10‐Phenanthroline: Synthesis, Crystal Structure and Antioxidant Activity

Zeitschrift anorg allge chemie

2015

Three ternary rare earth [NdIII (1), SmIII (2) and YIII (3)] complexes based on 3‐[(4,6‐dimethyl‐2‐pyrimidinyl)thio]‐propanoic acid (HL) and 1,10‐phenanthroline (Phen) were synthesized and characterized by IR and UV/Vis spectroscopy, TGA, and single‐crystal X‐ray diffraction. The crystal structures showed that complexes 1–3 contain dinuclear rare earth units bridged by four propionate groups and are of general formula [REL3(Phen)]2·nH2O (for 1 and 2: n = 2; for 3: n = 0). All rare earth ions are nine‐coordinate with distorted mono‐capped square antiprismatic coordination polyhedra. Complex 1 crystallizes in the monoclinic system, space group P21/c with a = 16.241(7) Å, b = 16.095(7) Å, c = 19.169(6) Å, β = 121.48(2)°. Complex 2 crystallizes in the monoclinic system, space group P21/c with a = 16.187(5) Å, b = 16.045(4) Å, c = 19.001(4) Å, β = 120.956(18)°. Complex 3 crystallizes in the triclinic system, space group P1 with a = 11.390(6) Å, b = 13.636(6) Å, c = 15.958(7) Å, α = 72.310(17)°, β = 77.548(15)°, γ = 78.288(16)°. The antioxidant activity test shows that all complexes own higher antioxidant activity than free ligands.

“…Solution-reaction calorimetry is a broad and versatile technique and has the advantages of being rapid, accurate, economic, and convenient. It is widely applied to the measurements of enthalpies of reaction, dissolution, dilution, mixing, adsorption, formation, and excess enthalpies. − To further study the thermodynamic properties of rare earth coordination complexes, this article reports the synthesis and characterization of coordination complexes of [Pr(C 6 H 4 NO 2 ) 2 C 9 H 6 NO], [Pr(C 6 H 4 NO 3 ) 3 ·2H 2 O], and [Pr(C 9 H 6 NO) 3 ·4H 2 O]. In particular, its thermodynamic properties were investigated by an advanced solution–reaction isoperibol microcalorimeter which greatly improved the accuracy of the dissolution enthalpies of samples, with an accuracy of 99.5%.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Thermochemical Study on Complexes of Praseodymium(III) with Niacin or 8-Hydroxyquinoline

Jiang

et al. 2013

J. Chem. Eng. Data

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 Δf H m Θ[Pr(C6H4NO2)2C9H6NO(s), 298.15 K] = −(1448.3 ± 2.6) kJ·mol–1, Δf H m Θ[Pr(C6H4NO3)3·2H2O(s), 298.15 K] = −(2256.1 ± 2.9) kJ·mol–1, and Δf H m Θ[Pr(C9H6NO)3·4H2O(s), 298.15 K] = −(1975.3 ± 4.6) kJ·mol–1.