摘要
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-1和ΔtrsSm,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.
The crystalline bis（n-undecylammonium）tetrachlorocadmiumate （CllH23NH3）2CdCI4（s） [abbre- viated as CllCd（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·mo1^-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,l=（321.88±0.07） K,△trsHm, l=-（37.59±0.17） kJ·mol^-1 and △trsSm,l= （117.24±0.12） J·K^-l·mol^-1 for the first peak; Ttrs,2=（323.81±0.30） K, △trsHm,2 = （12.42± 0.02） kJ·mol^-1 and △trsSm,2=-（38.36±0.09） J·K^-l·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 based on the fitted polynomials. K of the complex were calculated with an interval of 5 K
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2012年第7期889-896,共8页
Acta Chimica Sinica
基金
国家自然科学基金(Nos.20673050,20973089)资助项目~~
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
Keywords bis（n-undecylammonium）tetrachlorocadmiumate
crystal structure
lattice potential energy
low-temperature heat capacity
solid-solid phase transition
thermodynamic function
