化学学报 ›› 2012, Vol. 70 ›› Issue (07): 889-896 .DOI: 10.6023/A1110152 上一篇    下一篇

研究论文

四氯合镉酸正十一烷铵的合成、晶体结构及低温热容

卢冬飞, 邸友莹, 窦建民   

  1. 山东省化学储能与新型电池技术重点实验室 聊城大学化学化工学院 聊城 252059
  • 收稿日期:2011-10-15 修回日期:2011-12-12 出版日期:2012-04-14 发布日期:2012-01-20
  • 通讯作者: 邸友莹
  • 基金资助:

    国家自然科学基金(Nos. 20673050, 20973089)资助项目.

Synthesis, Crystal Structure and Low-temperature Heat Capacities of Bis(n-undecylammonium)tetrachlorocadmiumate

Lu Dongfei, Di Youying, Dou Jianmin   

  1. Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059
  • Received:2011-10-15 Revised:2011-12-12 Online:2012-04-14 Published:2012-01-20
  • Supported by:

    Project was supported by the National Natural Science Foundation of China (Nos. 20673050, 20973089).

合成了四氯合镉酸正十一烷铵配合物(C11H23NH3)2CdCl4(s)[简写: C11Cd(s)]. 用X 射线单晶衍射技术、化学分析和元素分析确定其晶体结构和化学组成. 利用其晶体学数据计算出晶格能为: UPOT=908.18 kJ·mol-1. 利用精密自动绝热热量计测定了它在78~395 K 温区的低温热容, 结果表明, 该配合物在此温区出现两次连续的固-固相转变, 计算出两次相变的峰温、摩尔焓及摩尔熵分别为: Ttrs,1=(321.88±0.07) K, ΔtrsHm,1=(37.59±0.17) kJ·mol-1, ΔtrsSm,1=(117.24±0.12) J·K-1·mol-1, Ttrs,2=(323.81±0.30) K, ΔtrsHm,2=(12.42±0.02) kJ·mol-1ΔtrsSm,2=(38.36±0.09) J·K-1·mol-1. 用最小二乘法将实验摩尔热容对温度进行拟合, 得到热容随温度变化的多项式方程. 用此方程进行数值积分,得到此温区每隔5 K 的舒平热容值和相对于298.15 K 时的热力学函数值.

关键词: 四氯合镉酸正十一烷铵, 晶体结构, 晶格能, 低温热容, 固-固相转变, 热力学函数

The crystalline bis(n-undecylammonium)tetrachlorocadmiumate (C11H23NH3)2CdCl4(s) [abbreviated as C11Cd(s)] was synthesized. The crystal structure and composition of the complex were determined by single crystal X-ray diffraction, chemical analysis and elementary analysis. The lattice potential energy was calculated to be UPOT=908.18 kJ·mol-1 from crystallographic data. Low-temperature heat capacities of the complex were measured by a precision automatic adiabatic calorimeter over the temperature range from 78 to 395 K. The experimental results show that there are two continuous phase changes appearing in the temperature region. The peak temperatures, molar enthalpies and entropies of two phase transitions for the complex were determined to be: Ttrs,1=(321.88±0.07) K, ΔtrsHm,1=(37.59±0.17) kJ·mol-1 and ΔtrsSm,1= (117.24±0.12) J·K-1·mol-1 for the first peak; Ttrs,2=(323.81±0.30) K, ΔtrsHm,2=(12.42±0.02) kJ· mol-1 and ΔtrsSm,2=(38.36±0.09) J·K-1·mol-1 for the second peak. Two polynomial equations of the heat capacities as a function of the temperature were fitted by least square method. The smoothed heat capacities and thermodynamic functions relative to 298.15 K of the complex were calculated with an interval of 5 K based on the fitted polynomials.

Key words: bis(n-undecylammonium)tetrachlorocadmiumate, crystal structure, lattice potential energy, low-temperature heat capacity, solid-solid phase transition, thermodynamic function