Synthesis, crystal structure and Hirshfeld surface analysis of a 1D coordination polymer catena-poly[[di-aqua-bis-(nicotinamide-κN1)nickel(II)]-μ-fumarato-κ2O1:O4].

The reaction of NiCl2 with fumaric acid and nicotinamide in basic solution produces the title polymeric complex, [Ni(C4H2O4)(C6H6N2O)2(H2O)2] n . The NiII cation, located on an inversion centre, is coordinated by two O atoms of the fumarate dianions, two N atoms from nicotinamide ligands and two water mol-ecules in a distorted octa-hedral fashion. In the crystal, the fumarate dianions bridge the NiII cations, forming polymeric chains propagating along the [101] direction; the polymeric chains are further linked by O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds, forming a three-dimensional supra-molecular architecture. Hirshfeld surface analyses and two-dimensional fingerprint plots were used to analyse the inter-molecular inter-actions present in the crystal, indicating that the most important contributions for the crystal packing are from H⋯O/O⋯H (35.9%), H⋯H (31.7%) and C⋯C (10.4%) inter-actions.