Two coordination compounds of rare earth perchlorates with alanine and imidazole, [RE(Ala)n(Im)(H2O)]- (ClO4)3(s) (RE=La, n=3; RE=Nd, n=2), have been prepared and characterized. The standard molar enthalpies of reacti...Two coordination compounds of rare earth perchlorates with alanine and imidazole, [RE(Ala)n(Im)(H2O)]- (ClO4)3(s) (RE=La, n=3; RE=Nd, n=2), have been prepared and characterized. The standard molar enthalpies of reaction for the following two reactions, LaCl37H2O(s)+3Ala(s)+Im(s)+3NaClO4(s)=[La(Ala)3(Im)(H2O)]- (ClO4)3(s)+3NaCl(s)+6H2O(l) (1) and NdCl36H2O(s)+2Ala(s)+Im(s)+3NaClO4(s)=[Nd(Ala)2(Im)(H2O)]- (ClO4)3(s)+3NaCl(s)+5H2O(l) (2), were determined by solution-reaction calorimetry, at T=298.15 K, as 36.168±0.642 kJmol-1 and 48.590±0.934 kJmol-1 respectively. From the results and other auxiliary quantities, the standard molar enthalpies of formation of [La(Ala)3(Im)(H2O)](ClO4)3(s) and [Nd(Ala)2(Im)(H2O)] (ClO4)3(s) were derived, fmHD!{[La(Ala)3(Im)(H2O)](ClO4)3, s}=(-2984.8±1.0) kJmol-1 and fmHD! {[Nd(Ala)2(Im)(H2O)]- (ClO4)3, s}=(-2387.8±0.8) kJmol-1 , respectively.展开更多
A coordination compound of erbium perchlorate with L-α-glutamic acid, [Er2（Glu）2（H2O）6]（ClO4）4·6H2O（s）, was synthesized. By chemical analysis, elemental analysis, FTIR, TG/DTG, and comparison with releva...A coordination compound of erbium perchlorate with L-α-glutamic acid, [Er2（Glu）2（H2O）6]（ClO4）4·6H2O（s）, was synthesized. By chemical analysis, elemental analysis, FTIR, TG/DTG, and comparison with relevant literatures, its chemical composition and structure were established. The mechanism of thermal decomposition of the complex was deduced on the basis of the TG/DTG analysis. Low-temperature heat capacities were measured by a precision automated adiabatic calorimeter from 78 to 318 K. An endothermic peak in the heat capacity curve was observed over the temperature region of 290-318 K, which was ascribed to a solid-to-solid phase transition. The temperature Ttrans, the enthalpy △transHm and the entropy △transSm of the phase transition for the compound were determined to be： （308.73±0.45） K, （10.49±0.05） kJ·mol^-1 and （33.9±0.2） J·K^-1·mol^-1. Polynomial equation of heat capacities as a function of the temperature in the region of 78-290 K was fitted by the least square method. Standard molar enthalpies of dissolution of the mixture [2ErCl3·6H2O（s）＋2L-Glu（s）＋6NaClO4·H2O（s）] and the mixture {[Er2（Glu）2（H2O）6]（ClO4）4·6H2O（s）＋6NaCl（s）} in 100 mL of 2 mol·dm^-3 HClO4 as calorimetric solvent, and {2HClO4（1）} in the solution A＇ at T=298.15 K were measured to be, △dHm,1=（31.552±0.026） kJ·mol^-1, △dHm,2 = （41.302±0.034） kJ·mol^-1, and △dHm,3 = （ 14.986 ± 0.064） kJ·mol^-1, respectively. In accordance with Hess law, the standard molar enthalpy of formation of the complex was determined as △fHm-=-（7551.0±2.4） kJ·mol^-1 by using an isoperibol solution-reaction calorimeter and designing a thermochemical cycle.展开更多
基金Project supported by the Teaching and Research Award Program for Outstanding Young Professors in High Education Institute Ministry of Educa-tion China.
文摘Two coordination compounds of rare earth perchlorates with alanine and imidazole, [RE(Ala)n(Im)(H2O)]- (ClO4)3(s) (RE=La, n=3; RE=Nd, n=2), have been prepared and characterized. The standard molar enthalpies of reaction for the following two reactions, LaCl37H2O(s)+3Ala(s)+Im(s)+3NaClO4(s)=[La(Ala)3(Im)(H2O)]- (ClO4)3(s)+3NaCl(s)+6H2O(l) (1) and NdCl36H2O(s)+2Ala(s)+Im(s)+3NaClO4(s)=[Nd(Ala)2(Im)(H2O)]- (ClO4)3(s)+3NaCl(s)+5H2O(l) (2), were determined by solution-reaction calorimetry, at T=298.15 K, as 36.168±0.642 kJmol-1 and 48.590±0.934 kJmol-1 respectively. From the results and other auxiliary quantities, the standard molar enthalpies of formation of [La(Ala)3(Im)(H2O)](ClO4)3(s) and [Nd(Ala)2(Im)(H2O)] (ClO4)3(s) were derived, fmHD!{[La(Ala)3(Im)(H2O)](ClO4)3, s}=(-2984.8±1.0) kJmol-1 and fmHD! {[Nd(Ala)2(Im)(H2O)]- (ClO4)3, s}=(-2387.8±0.8) kJmol-1 , respectively.
基金Project supported by the National Natural Science Foundation of China （No. 20673050）.
文摘A coordination compound of erbium perchlorate with L-α-glutamic acid, [Er2（Glu）2（H2O）6]（ClO4）4·6H2O（s）, was synthesized. By chemical analysis, elemental analysis, FTIR, TG/DTG, and comparison with relevant literatures, its chemical composition and structure were established. The mechanism of thermal decomposition of the complex was deduced on the basis of the TG/DTG analysis. Low-temperature heat capacities were measured by a precision automated adiabatic calorimeter from 78 to 318 K. An endothermic peak in the heat capacity curve was observed over the temperature region of 290-318 K, which was ascribed to a solid-to-solid phase transition. The temperature Ttrans, the enthalpy △transHm and the entropy △transSm of the phase transition for the compound were determined to be： （308.73±0.45） K, （10.49±0.05） kJ·mol^-1 and （33.9±0.2） J·K^-1·mol^-1. Polynomial equation of heat capacities as a function of the temperature in the region of 78-290 K was fitted by the least square method. Standard molar enthalpies of dissolution of the mixture [2ErCl3·6H2O（s）＋2L-Glu（s）＋6NaClO4·H2O（s）] and the mixture {[Er2（Glu）2（H2O）6]（ClO4）4·6H2O（s）＋6NaCl（s）} in 100 mL of 2 mol·dm^-3 HClO4 as calorimetric solvent, and {2HClO4（1）} in the solution A＇ at T=298.15 K were measured to be, △dHm,1=（31.552±0.026） kJ·mol^-1, △dHm,2 = （41.302±0.034） kJ·mol^-1, and △dHm,3 = （ 14.986 ± 0.064） kJ·mol^-1, respectively. In accordance with Hess law, the standard molar enthalpy of formation of the complex was determined as △fHm-=-（7551.0±2.4） kJ·mol^-1 by using an isoperibol solution-reaction calorimeter and designing a thermochemical cycle.
