The novel nickel complex with the extended-TTF dithiolate ligand [Ni(tmdt)(2)](tmdt = trimethylenedithiotetrathiafulvalenedithiolate) is the first single- component molecular crystal with metallic state down to very low temperature. Recently, a direct evidence for the presence of three-dimensional electron and hole Fermi surfaces was obtained by detecting de Haars-van Alphen (dHvA) oscillations of this system. An isostructural highly conducting [Au( tmdt)(2)] system (sigma(RT) approximate to 50 Scm(-1) (compaction pellet sample)) undergoes an anti-ferromagnetic transition around 110K without loss of its high conductivity (sigma(110K) > 20S cm(-1)). [Au(tmdt)(2)] is the first molecular conductor exhibiting the coexistence of p conduction electrons and magnetic order above 100 K.