A three-dimensional synthetic metallic crystal composed of single-component molecules

Molecular metals normally require charge transfer between two different che mical species. We prepared crystals of [Ni(tmdt)(2)] (tmdt, trimethylenetet rathiafulvalenedithiolate) and carried out crystal structure analyses and r esistivity measurements. The analyses and measurements revealed that these single-component molecular crystals are metallic from room temperature down to 0.6 kelvin. Ab initio molecular orbital calculations suggested that pi molecular orbitals form conduction bands. The compact molecular arrangement , intermolecular overlap integrals of the highest occupied and Lowest unocc upied molecular orbitals, and tight-binding electronic band structure calcu lation revealed that [Ni(tmdt)(2)] is a three-dimensional synthetic metal c omposed of planar molecules.