A second monoclinic polymorph of 2,3-di-phenyl-pyrazine.

The title com-pound, C16H12N2 (I), crystallizes in the space group P21/c with one mol-ecule in the asymmetric unit, in which the dihedral angles between the planes of the pyrazine ring and pendant phenyl rings are 53.12 (3) and 33.28 (3)°. In the crystal, pairwise C-H⋯N hy-dro-gen bonds link the mol-ecules into centrosymmetric dimers and aromatic π-π stacking inter-actions between the pyrazine rings of adjacent mol-ecules and C-H⋯π inter-actions help to consolidatate the packing. Compound I is a polymorph of the previously reported form of 2,3-di-phenyl-pyrazine [Kitano et al. (1983 ▸). Acta Cryst. C39, 136-139], which crystallizes in the space group C2/c with two mol-ecules in the asymmetric unit. The Hirshfeld surfaces and energy frameworks of the two polymorphs are com-pared and the bonding modes of the mol-ecules as ligands are surveyed.