Supramolecular interaction patterns in the zinc(II) dichloride and tin(IV) tetrachloride complexes with dipyrido[f,h]quinoxaline-6,7-dicarbonitrile

This study characterizes the supra-molecular synthons that dominate the inter-molecular organization of the title compounds, namely dichloridobis(dipyrido[f,h]quinoxaline-6,7-dicarbonitrile)zinc(II), [ZnCl2(C16H6N6)2], (I), and tetrachlorido(dipyrido[f,h]quinoxaline-6,7- dicarbonitrile)tin(IV), [SnCl4(C16H6N6)], (II), in their respective crystal structures. Mol-ecules of (I) are located on 2^b axes of rotational symmetry. Their crystal packing is stabilized mostly by π-π stacking and dipole-dipole attractions between the organic ligand fragments of inversion-related neighbouring species, as well as by weak inter-molecular C - H⋯N hydrogen bonds. On the other hand, Cl⋯π and N⋯π inter-actions seem to direct the crystal packing in (II), which is unusual in the sense that its aromatic fragments are not involved in π-π stacking. Mol-ecules of (II) are located on m^b planes of mirror symmetry. This study confirms the diverse structural chemistry of this organic ligand, which can be involved in a wide range of supra-molecular inter-actions. These include effective coordination to various metal ions via the phenathroline N-atom sites, π-π stacking and π⋯halogen contacts through its extended π-system, and hydrogen bonding and N⋯π inter-actions through its nitrile groups. The competing natures of the latter make it difficult to predict a priori the preferred supra-molecular motif that may form in a given structure.