A second monoclinic polymorph of 2,3-diphenylpyrazine

The title com-pound, C₁₆H₁₂N₂ (<b>I</b>), crystallizes in the space group <i>P</i>2₁/<i>c</i> 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 <b>I</b> is a polymorph of the previously reported form of 2,3-di-phenyl-pyrazine [Kitano <i>et al.</i> (1983 ▸). <i>Acta Cryst.</i> C<b>39</b>, 136-139], which crystallizes in the space group <i>C</i>2/<i>c</i> 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.