Gold complexes with dithiothiophene ligands: A metal based on a neutral molecule

The gold complexes n-Bu4N-[Au(alpha -tpdt)(2)] (5), n-Bu4N[Au(tpdt)(2)] (4) and n-Bu4N[Au(tpdt)(2)] (6) based on new dithiothiophene ligands (alpha -t pdt= 2,3-thiophenedithiolate, dtpdt = 2,3-dihydro-5,6-thiophenedithiolate a nd tpdt = 3,4-thiophenedithiolate) nave been prepared and characterised. Th ese gold(III) complexes are diamagnetic, but they can be oxidised with iodi ne to the ;paramagnetic compounds [Au(alpha -tpdt)(2)] (8), [Au(dtpdt)(2)] (7) and n-Bu4N-[{Au(tpdt)(2)}(n similar to2)] (9), which were isolated as f ine powders and which exhibit para-magnetic susceptibilities that are almos t temperature independent with room temperature values of 2.5 x 10(-4), 2.0 x 10(-4) and 5 x 10(-4) emu mol(-1), respectively. Interestingly, the neut ral complex [Au(alpha -tpdt)(2)] (8) as a polycrystalline sample displays t he properties of a metallic system with a room temperature electrical condu ctivity of 6 S cm(-1) and a thermoelectric power of 5.5 mu VK-1; this is th e first time that this metallic property has been observed in a molecular s ystem based on a neutral species.