Thermochemical properties of the rare earth complexes with pyromellitic acid
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- 作者：Lijun Wang ; Fei Liu ; Xuwu Yang ; Xiaoyan Wang ; Ruiping Liu ; Sa Zhao ; Sanping Chen
- 关键词：Rare earth complex ; Thermal analysis ; The enthalpy of combustion ; The enthalpy of formation ; Precise rotating-bomb calorimeter
- 刊名：Thermochimica Acta
- 出版年：2009
- 出版时间：1 June 2009
- 年：2009
- 卷：490
- 期：1-2
- 页码：43-46
- 全文大小：280 K
文摘
Fourteen rare earth complexes with pyromellitic acid were synthesized and characterized by means of chemical and elemental analysis, and TG–DTG. The constant-volume combustion energies of complexes, ΔcU, were measured by a precise rotating-bomb calorimeter (RBC-type II). Their standard molar enthalpies of combustion, , and standard molar enthalpies of formation, , were calculated at T = 298.15 K. The relationship of and with the atomic numbers of the elements in the lanthanide series was examined. The results show that a certain amount of covalence is present in the chemical bond between rare earth cations and the ligand.