Crystal engineering is a sub-discipline of supramolecular chemistry and concerns the construction of crystalline materials using non-covalent interactions [1]. Organic and inorganic crystal engineering studies offers several strategies to attach the molecules based upon the presence of functional groups and related intermolecular interactions such as hydrogen bond, halogen bond, . Moreover, different types of interaction with different strengths should be considered in the crystal structures analysis and also prediction of molecular arraignments [2]. In this regard, one can found that the weak non-covalent interactions has also an important role in the self-assembly of crystalline materials [3, 4]. In this work, two new Hg (II) complexes, [HgBr2(L)2] and [HgCl2(L)2], containing the N-(1,3- Thiazol-2-yl)-2-pyrazinecarboxamide ligand (L) have been prepared and characterized by elemental analysis and IR spectroscopy. The crystal structure of ligand has been elucidated by single crystal X-ray diffraction. The crystal structures were determined by N thiazole (R2 2(8)synthon) classical hydrogen bonding interaction. In our design, the presence of thiazole and pyrazine as hetero aromatic rings could -based interactions to form packing structure. The hydrogen atoms of thiazole ring generate C-Hthiazole pyrazine interaction as a non-classical hydrogen bond. There is also pyrazine thiazole and C-Hpyrazine interactions.

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