The Copper Salt of 2‐Iodo‐5‐methyl‐N,N′‐dicyanoquinonediimine—a Radical Anion Salt Exhibiting Metallic Conductivity down to Low Temperatures

The title compound 1b is a radical anion salt whose conductivity increases continuously down to 1.2 K. This property is surprising since similar highly conductive salts of the type 1, X = Me, Cl, Br; M = Cu, Ag, alkali metal (exception: 1a), undergo a transition to a semiconducting state between 300 and 100 K.