Journal of Chemical Thermodynamics, Vol.34, No.2, 133-153, 2002
Thermodynamics, phase transitions and crystal structure of ammonium hexahalides: comparative study of the heat capacity and thermodynamic properties of (NH4)(2)PtCl6, (ND4)(2)PtCl6, (NH4)(2)PtBr6, (ND4)(2)PtBr6, (NH4)(2)PdCl6, (ND4)(2)PdCl6, (NH4)(2)TeCl6, (ND4)(2)TeCl6, and (NH4)(2)RuCl6 from 5 K to 350 K-a
The results from recent measurements of heat capacity, crystal structure and related properties as well as thermodynamic properties of 27 members of the hexahalogenated metal salts to include the alkali, ammoniated and deuterated forms are compared over a wide range of temperature. A detailed comparison is provided for the pairs (NH4)(2)PtCl6, (ND4)(2)PtCl6; (NH4)(2)PtBr6, (ND4)(2)PtBr6; (NH4)(2)PdCl6, (ND4)(2)PdCl6; (NH4)(2)TeCl6, (ND4)(2)TeCl6; and (NH4)(2)RuCl6 from 5 K to 350 K. A discussion is summarised that includes the known roles played by the cations and anions inducing structural phase transitions. The preliminary results for heat capacity measurements of (NH4)(2)RuCl6 are reported for the first time. Crown Copyright
Keywords:ammonium hexachloroplatinate;ammonium hexabromoplatinate;ammonium hexachloropallidate;ammonium hexachlorotellurate;ammonium hexachlororuthenate;crystal structure;heat capacity;R2MX6 stability