1-{2-[4-(4-Nitro­phen­yl)piperazin-1-yl]eth­yl}-4-aza-1-azoniabicyclo­[2.2.2]octane iodide

The title compound, C(18)H(28)N(5)O(2) (+)·I(−), was observed as a main product in an intended 1:1 reaction between 4-iodo­nitro­benzene and 1,4-diaza­bicyclo­[2.2.2]octane (DABCO). In the reaction, DABCO undergoes a ring opening to yield a quaternary salt of DABCO and 1-ethyl-4-(4-nitro­phen­yl)piperazine with an iodide anion. The crystal structure determination was carried out as no crystal structure had been previously reported in the investigations describing the corresponding reaction with 4-chloro­nitro­benze. Indeed, the crystal structure of the title compound confirms the mol­ecular composition proposed earlier for the analogous chloride salt. The cation conformation is similar to the previously reported dinitro analogue 1-{2-[4-(2,4-dinitro­phen­yl)piperazin-1-yl]eth­yl}-4-aza-1-azoniabicyclo­[2.2.2]octane chloride [Clegg et al. (2004 ▶). Acta Cryst. E60, o291–o293]. The crystal packing is dominated by cation⋯I(−) inter­actions in addition to weak inter­molecular C—H⋯O(2)N and C—H⋯N inter­actions between the cations.