A series of novel aromatic compounds with a planar N6 ring

A series of novel aromatic compounds ScN 6 - , VN 6 + , Ca2N6, and ScN6Cu, including a previously reported TiN6, are found to be local minima with C6v, C6v, D6h, and Cs symmetry, respectively, at the B3LYP/6-311+G∗ level of theory. These compounds may be regarded as 10π-electron complexes containing one or two metal cations and a planar N 6 4 - ring. They are predicted to have aromatic character. The nucleus-independent chemical shifts (NICS), the molecular orbitals, and the HOMO–LUMO gap analysis confirm that the planar N 6 4 - ring indeed exhibits aromaticity, which is remarkably enhanced by the incorporation of metal atom in these metal–N6 molecules.