Diamond lattice in single-component molecular crystals comprising tetrabenzoporphyrin neutral radicals.

A single-component molecular radical crystal of Co III (tbp˙ - )(CN) 2 , where tbp = tetrabenzoporphyrinato ligand, exhibiting a diamond lattice was fabricated as a potential candidate for a three-dimensional Dirac electron system. Band structure calculations revealed that the Fermi energy level was located at the Dirac point. A small electrical resistivity of 160 Ω cm was observed at 2 K under the application of 2.4 GPa. Furthermore, substituting Co III by Fe III or Mn III led to the introduction of local magnetic moments into the diamond-lattice system. M III (tbp˙ - )L 2 crystals will open up uncharted fields in the study of the Dirac electron systems.