Derivatives of heterocyclic compounds are valuable chemotherapeutic agents [1]. Pyrazine ring is present in a number of naturally occurring compounds in the form of pteridins and in antibiotics like aspergillic acid. Pyrazine ring is a part of numerous drugs. The first of them was pyrazine carboxamide (pca), the first-line antimycobacterial agent, for which promising antibacterial and antifungal activity have been reported [2, 3]. Thence, on another hand, this multidentate ligand is an attractive target for crystal engineering.  Polycarboxylate ligands are a family of organic building blocks that play an important role in coordination chemistry, and have been justified as efficient and versatile candidates for the design and synthesis of a variety of metal coordination polymers [4]. Employment of mixedligand approach has allowed the construction of frameworks with a greater variety of structural motifs, compared with using only one type of ligands. Hence, introduction of auxiliary ligands such as aromatic N-donors into the reaction systems can result in wide variety of architectures. Herein we have combined the Cu(II)/Zn(II)/Cd(II) metal centers with two types of ligands: pyrazine carboxamide (pca) and dicarboxylic acids including malonic acid (H2mal) and 1,4-benzenedicarboxylic acid (H2bdc). Four coordination compounds, including one binuclear complex [Cu2(mal)2(pca)2]·H2O (1), two 1D polymeric [Zn(mal)(pca)(H2O)]n (2), [Cu(CH3COO)2(pca)]n (3) and one 2D polymeric [Cd(bdc)(pca)(H2O)]n (4) compounds have been prepared, and their crystal structures have been determined by single crystal X-ray diffraction. The pca coordinates to the metal centers as a neutral ligand in a monodentate (a), bidentate bridging (b) and chelating modes (c) (Figure 1), while the bidentate acetate, malonate and terephthalate anionic ligands provide extensions of structures. Notably, only in complex catena-[(μ2-naphthalene-1,4dicarboxylato)-bis(μ2-pyrazine-2-carboxamide)-di-silver] [5] the pca ligand reveals the bidentate bridging coordination mode (Figure 1b).      (a) (b) (c) Figure 1. Versatile coordination modes of pyrazine carboxamide molecule in the Cd(II) (a), Cu(II) (b and c), and Zn(II) (c) coordination compounds.   Compound 2 is the most effectively packed compound with the highest PI (75.4%), while  only crystal structure of 4 contains negligible solvent accessible voids (4.5%), PI=67.5%. Luminescent properties of coordination polymers 2 and 4 are in progress.