title: 1-[Bicyclo[4.2.0]octa-1(6),2,4-trien-3-yl]-3-[bicyclo[4.2.0]octa-1(6),2,4-trien-3-yl-methyl]imidazolium hexa-fluoro-phos-phate.
abstract: In the title compound, C(20)H(19)N(2) (+)·PF(6) (-), the two benzocyclo-butene units are essentially planar and they form dihedral angles of 38.0 (2) and 72.7 (2)°, with the central imidazolium ring. In the crystal structure, weak C-H⋯π and π--π stacking inter-actions [centroid-centroid distance = 3.742 (2) Å] contribute to the stability of the crystal structure. The PF(6) (-) ion is disordered over two positions with site occupancies of 0.869 (9) and 0.131 (9).
authors.forename: Fang-Hua
authors.initials: FH
authors.lastname: Zhu
authors.forename: Jun-Xiao
authors.initials: JX
authors.lastname: Yang
authors.forename: Zhi-Hua
authors.initials: ZH
authors.lastname: Mao
authors.forename: Ru-Gang
authors.initials: RG
authors.lastname: Xie