Low-temperature heat capacity and standard entralpy of formation of neodymium glycine perchlorate complex [Nd-2(Gly)(6)(H2O)(4)](ClO4)(6)center dot 5H(2)O

摘要

Rare-earth perchlorate complex coordinated with glycine [Nd-2(Gly)(6)(H2O)(4)](ClO4)(6)center dot 5H(2)O was synthesized and its structure was characterized by using thermogravimetric analysis (TG), differential thermal analysis (DTA), chemical analysis and elementary analysis. Its purity was 99.90%. Heat capacity measurement was carried out with a high-precision fully-automatic adiabatic calorimeter over the temperature range from 78 to 369 K. A solid-solid phase transformation peak was observed at 256.97 K, with the enthalpy and entropy of the phase transformation process are 4.438 kJ mol(-1) and 17.270 J K-1 mol(-1), respectively. There is a big dehydrated peak appears at 330 K, its decomposition temperature, decomposition enthalpy and entropy are 320.606 K, 41.364 kJ mol(-1) and 129.018 J K-1 mol(-1), respectively. The polynomial equations of heat capacity of this compound in different temperature ranges have been fitted. The standard enthalpy of formation was determined to be -8023.002 kJ mol(-1) with isoperibol reaction calorimeter at 298.15 K.