ACTA CRYSTALLOGRAPHICA SECTION E-CRYSTALLOGRAPHIC COMMUNICATIONS, vol.71, pp.479-489, 2015 (ESCI)
The asymmetric unit of the title coordination polymer, [Zn(C7H4NO4)(2)(C6H6N2O)(2)](n), contains two 4-nitrobenzoate (NB) anions and two nicotinamide (NA) ligands. The Zn-II atom has a slightly distorted octahedral coordination sphere. In the equatorial plane, it is coordinated by three carboxylate O atoms of the NB anions and one O atom of one of the two NA ligands. The axial positions are occupied by the pyridine N atoms of the two NA ligands. In the two NB anions, the carboxylate groups are twisted away from the attached benzene rings by 13.8 (2) and 13.4 (2)degrees, while the benzene rings are oriented at a dihedral angle of 11.5 (2)degrees. The dihedral angle between the NA rings is 10.3 (1)degrees. Only one of the two NB anions and one of the two NA ligands bridge adjacent Zn II ions through eight-and twelve-membered rings, respectively, forming polymeric chains running along the a-axis direction. In the crystal, N-H center dot center dot center dot O hydrogen bonds link adjacent chains, enclosing R(16), R-2(2)(20) and R-6(6)(16) ring motifs, forming layers parallel to (01 (1) over bar). The layers are linked via a number of C-H center dot center dot center dot O hydrogen bonds, forming a three-dimensional network.