The First Molecular Superconductor Based on π-Acceptor Molecules and Closed-Shell Cations, [(CH3)4N][Ni(dmit)2]2, Low-Temperature X-Ray Studies and Superconducting Transition

Abstract Low-temperature structural study of [(CH3)4N][Ni(dmit)2]2 suggested that the rotational freedom of methyl group seems to play an important role in the “metal-semimetal” transition. Superconducting transition was observed at 5 K (7 kbar).