title: 2,2'-(p-Phenyl-ene)bis-(4,5-dihydro-1H-imidazol-3-ium) bis-(3-nitro-benzoate).
abstract: In the title compound, C(12)H(16)N(4) (+)·2C(7)H(4)NO(4) (-), the complete 2,2'-(p-phenyl-ene)bis-(4,5-dihydro-1H-imidazol-3-ium) (bib) dication is generated by crystallographic inversion symmetry. The bib cations reside on crystallographic inversion centers, which coincide with the centroids of the respective benzene rings. In the cation, the imidazole ring adopts an envelop conformation with the flap atom displaced by 0.082 (3) Å from the plane through the other ring atoms. In the crystal, the cations and anions are linked through inter-molecular N-H⋯O hydrogen bonds, forming chains running along the a axis. C-H⋯O inter-actions also occur. Weak π-π contacts between the imidazole rings of bib and between the benzene rings of NB [centroid-centroid distances = 3.501 (1) and 3.281 (2) Å, respectively] may further stabilize the structure.
authors.forename: Xiu-Mei
authors.initials: XM
authors.lastname: Song
authors.forename: Jun-Jun
authors.initials: JJ
authors.lastname: Li
authors.forename: Xin-Hua
authors.initials: XH
authors.lastname: Liu
authors.forename: Chun-Xia
authors.initials: CX
authors.lastname: Ren
authors.forename: Shao-Ming
authors.initials: SM
authors.lastname: Shang