| Abstract
| - Heat capacity of halogen-bridged one-dimensional binuclear metal complex (so-called MMX chain) havingfour n-pentyl groups, Pt2(n-PenCS2)4I, was measured by adiabatic calorimetry. A first-order phase transitionwas observed at 207.4 K when measurement was made after cooling from room temperature. The enthalpyand entropy of transition were determined to be 10.19 kJ mol-1 and 49.1 J K-1 mol-1, respectively. Amonotropic phase transition was observed at 324 K on heating, and the entropy of transition was essentiallynull. The sample once heated above 324 K never returned to the initial phase at room temperature and underwenta higher-order phase transition at 173 K and a first-order phase transition at 220.5 K. The enthalpy andentropy of the first-order phase transition were estimated to be 11.6 kJ mol-1 and 52.4 J K-1 mol-1, respectively.The magnitude of the entropy gain at the phase transition from the initial room-temperature phase to thehigh-temperature phase at 324 K shows that in Pt2(n-PenCS2)4I a large amount of entropy reserved in alkylchain is transferred to dithiocarboxylato groups upon the phase transition, as in the cases of Pt2(n-PrCS2)4Iand Pt2(n-BuCS2)4I.
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