Physical properties of metal cluster compounds II: Dc-conductivity of the high-nuclearity gold cluster compound Au55(PPh3)12Cl6

The title compound consists of (electrically neutral) Au55(PPh3)12Cl6 macromolecules, where each molecule is composed of a core of 55 Au-atoms in a cuboctahedral packing, surrounded by a shell of 12 phosphine and 6 chlorine ligands. We present dc-electrical resistance data in the range 70 to 350 K, which can be described by R∝exp(To/T)12, with To = 5.7 × 104 K. This same temperature dependence has also been observed in granular metal systems and in some 1-dimensional conductors. Similar as in those systems, we observe strong non-ohmic effects in the conductivity, which become more pronounced as the temperature is lowered.