Synthesis and structure of a binuclear calcium nitrate coordination complex with bridging zwitterionic nicotinic acid.

The title coordination complex, bis-(μ-pyridin-1-ium-3-carboxyl-ato-κ2 O:O')bis-[di-aqua-bis-(nitrato-κ2 O,O')calcium(II)], [Ca2(C6H5NO2)2(NO3)4(H2O)4], was prepared from calcium nitrate and nicotinic acid in a water-ethanol solvent mixture. The asymmetric unit contains a half mol-ecule of the complex, with the calcium atom exhibiting a coordination number of eight, forming a distorted dodeca-hedral geometry with a mixed-ligand environment. The μ2-O,O' bridging zwitterionic nicotinic acid mol-ecules generate a centrosymmetric dinuclear complex. The extended structure features N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds, which generate a three-dimensional network. Hirshfeld surface and two-dimensional fingerprint plot analyses were performed to qu-antify and visualize the inter-molecular inter-actions contributing to the overall cohesion of the structure.