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Low‐temperature Heat Capacities and Thermodynamic Properties of the Solid State Complexes (C 2 H 10 N 2 )MCl 4 (s) (M=Cu and Cd)
Author(s) -
Cao Yanping,
Chen Jingtao,
Di Youying,
He Donghua,
Dan Wenyan,
Liu Yupu
Publication year - 2010
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.201090381
Subject(s) - chemistry , crystal structure , adiabatic process , heat capacity , atmospheric temperature range , calorimetry , crystallography , solid state , lattice energy , thermodynamics , standard enthalpy of formation , analytical chemistry (journal) , physics , chromatography
The tetrachlorocuprate(II) ethylenediammonium and tetrachlorocadmate(II) ethylenediammonium were synthesized. Chemical analysis, elemental analysis, and X‐ray crystallography were applied to characterize the compositions and crystal structures of the two complexes. The lattice potential energies and the radiuses of the anions of two complexes were calculated to be U POT [(C 2 H 10 N 2 )CuCl 4 ]=1810.19 kJ·mol −1 , U POT [(C 2 H 10 N 2 )CdCl 4 ]=1784.39 kJ·mol −1 , r [(CuCl 4 ) 2− ]=0.308 nm, and r [(CdCl 4 ) 2− ]=0.321 nm from the data of the crystal structure, respectively. Low‐temperature heat capacities of the two complexes were measured by a precision automatic adiabatic calorimeter with the small sample over the temperature range from 78 to 400 K, respectively. Two polynomial equations of heat capacities against the temperatures were fitted by least square method: C p , m [(C 2 H 10 N 2 )CuCl 4 , s] =213.553+118.578 X −5.816 X 2 +4.392 X 3 +0.276 X 4 and C p , m [(C 2 H 10 N 2 )CdCl 4 , s] =190.927+98.501 X −7.931 X 2 +0.657 X 3 +3.834 X 4 , in which X = ( T −239)/161. Based on the fitted polynomial equations, the smoothed heat capacities and thermodynamic functions of the two complexes relative to the standard reference temperature 298.15 K were calculated at intervals of 5 K.