3-(4-Ferrocenylphen-yl)-1-(4-nitro-benz-yl)-1H-imidazol-3-ium hexa-fluorido-phosphate.

The asymmetric unit of the title salt, [Fe(C5H5)(C21H17N3O2]PF6, comprises a 1-(4-ferrocenylphen-yl)-3-(4-nitro-benz-yl)imidazolium cation paired with a hexa-fluorido-phosphate anion. The cation adopts a syn-periplanar arrangement, with the ferrocenylphenyl substituent tilted by 38.32 (7)° relative to the imidazolium core. The ferrocenyl fragment shows a nearly eclipsed conformation defined by a C(Cp)-Cg(Cp1)-Cg(Cp2)-C(Cp) torsion angle of -7.9° where Cg1 and Cg2 are the centroids of the cyclo-penta-dienyl rings of the ferrocenyl substituent. In the crystal, inter-ionic C-H⋯F hydrogen bonds generate graph-set motifs R 1 2(7) and R 2 1(4), assembling the ions into chains that propagate parallel to [001].