Crystal engineering deals with the evaluation and utilization of crystalline materials having ‎specific function and fascinating assemblies and architectures [1]. The key to designing ‎molecular building blocks understands the nature of the intermolecular interaction, which ‎assembles the building blocks and control of the weak interactions in the crystal packing [2]. In ‎this regard, π-based interactions of aromatic moieties (i.e. π…π and CH…π) have been found to ‎be a useful tool in the manipulation of the molecular components in the crystalline state. ‎Therefore, detailed information on these interactions from experimental and theoretical ‎measurements is essential for understanding of the role of them in the control of solid state and ‎self assembled structures [3-4].‎ In this work, from crystal engineering point of view as a flourishing field of research in modern ‎chemistry, two new Hg(II) complexes, [HgBr2(L)2] and [HgI2(L)2], containing the rigid N-(2-‎pyrazine)-thiophene-carboxamide ligand (L) have been prepared and characterized by elemental ‎analysis and IR spectroscopy. The crystal structures of these compounds have been elucidated ‎by single crystal X-ray diffraction. The crystal structures were determined mostly by N–H…N ‎classical hydrogen bonding interaction. According to rigidity of the ligand, in all compounds, ‎the hydrogen atoms of thiophene ring were pointed toward to generate CHThiophen…O(=C) ‎interaction as an non-classical hydrogen bond. There is also CHPyrazine…πThiophen interactions in ‎the crystal structures that cooperate with non-classical hydrogen bonds. ‎

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