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

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• 作者：Hui-Wen Gu ; Sheng-Xiong Xiao ; Hang-Ying Xiao ; Yun Xiao ; Ai-Tao Li ; Xiao-Li Hu ; Qiang-Guo Li
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2012
• 出版时间：April 4, 2012
• 年：2012
• 卷：51
• 期：13
• 页码：4797-4803
• 全文大小：337K
• 年卷期：v.51,no.13(April 4, 2012)
• ISSN：1520-5045

文摘

This article reports the synthesis and thermodynamic properties of a novel rare earth coordination complex, samarium chloride hexahydrate (SmCl₃路6H₂O) with nicotinic acid (C₆H₅NO₂) and 8-hydroxylquinoline (C₉H₇NO), whose composition and structure were characterized by elemental analysis, molar conductance, thermogravimetric analysis (TG鈥揇TG), 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^{鈥?/sup> formed a chelate ring with Sm3+ for coordination. The X-ray powder diffraction pattern demonstrated that the crystal type of [Sm(C₆H₄NO₂)₂路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鈥搑eaction isoperibol microcalorimeter. The standard molar enthalpy change of the coordination reaction was determined to be 螖_rH_m螛 = (167.49 卤 0.39) kJ路mol鈥?. The standard molar enthalpy of formation of the title complex, [Sm(C₆H₄NO₂)₂路C₉H₆NO], was estimated to be 螖_fH_m螛[Sm(C₆H₄NO₂)₂路C₉H₆NO(s), 298.15 K] = 鈭?1483.4 卤 2.4) kJ路mol鈥?, 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.}