1-[Bicyclo­[4.2.0]octa-1(6),2,4-trien-3-yl]-3-(but-3-en­yl)imidazolium bromide

In the title compound, C15H17N2 +·Br−, the cyclo­butene and benzene rings are coplanar. The dihedral angle between the benzene and imidazolium rings is 21.2 (3)°. In the crystal structure, the C15H17N2 + and Br− ions are linked into a zigzag chain along the b axis by C—H⋯Br hydrogen bonds, and weak C—H⋯π inter­actions involving the benzene ring of a screw-related cation

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-yl­methyl]imidazolium hexa­fluoro­phos­phate

In the title compound, C20H19N2 +·PF6 −, the two benzocyclo­butene 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 inter­actions [centroid–centroid distance = 3.742 (2) Å] contribute to the stability of the crystal structure. The PF6 − ion is disordered over two positions with site occupancies of 0.869 (9) and 0.131 (9)