A novel zinc(II) complex containing square pyramidal, octahedral and tetrahedral geometries on the same polymeric chain constructed from pyrazine-2,3-dicarboxylic acid and 1-vinylimidazole

In this study, a novel Zn(II) complex of pyrazine-2,3-dicarboxylic acid and 1-vinylimidazole was synthesized and fully characterized by elemental analysis, IR spectroscopy, thermal analysis, X-ray powder diffraction, and X-ray single crystal techniques. The X-ray single crystal data revealed that the polymeric coordination complex crystallizes in the monoclinic system with C2 space group and shows a peculiar feature as having the Zn(II) ions with four (tetrahedral), five (square pyramidal) and six (octahedral) coordination numbers on the same polymeric chain. In the complex, the pyrazine-2,3-dicarboxylato ligand acts as a bridging ligand via the ring nitrogen atoms and the carboxyl oxygen atoms while the 1-vinylimidazole ligand coordinates to the metal ion as monodentate via the ring nitrogen atom. In addition, the surface area and hydrogen adsorption studies were carried out and it was found that the complex has a small BET surface area but it can adsorb considerable amount of hydrogen gas at different pressures. Further, the accessible surface area and free volume of the Zn(II) complex were calculated at a Connolly diameter of 0.8 angstrom by the Grand Canonical Monte Carlo simulation.