Structural Phase Transition and Valence Fluctuation Observed in a New MMX Chain Compound, Pt2(<i>n</i>-PrCS2)4I

Abstract

Abstract A new one-dimensional iodo-bridged mixed-valence diplatinum(II,III) complex (MMX chain compound) with dithiobutanoate (n-PrCS2-) as a ligand, Pt2(n-PrCS2)4I, was found to undergo a structural phase-transition at 358–359 K by the differential scanning calorimetry (DSC) measurement and X-ray crystal structure analyses. In X-ray diffraction photographs measured using synchrotron radiation of the SPring-8 facility, the weak but distinct Bragg spots corresponding to the periodicity of 2-fold repetition length of a –Pt–Pt–I– unit were observed at 300 K and changed to diffuse scattering at 350 K. The electric conductivity deviates from the typical semiconducting behavior in the temperature region above 330 K.