N-Methyl-N′-(3-phthalimidopropyl)-4,4′-bipyridinium diiodide

The asymmetric unit of the title compound, C₂₂H ₂₁N₃O₂²⁺·2I^-, consists of a substituted bipyridinium cation and two iodide anions. The dihedral angle between the two rings within the phthalimide moiety is 1.7 (3)°, where the r.m.s. deviations for the five- and six-membered rings are 0.006 and 0.004 Å, respectively. On the other hand, the two pyridinium rings are tilted at an angle of 3.9 (3)° because of the steric contacts between the H atoms at the 3-, 5-, 3′- and 5′-positions of the 4,4′-bipyridinium moiety. The phthalimide plane is tilted by 68.5 (1)° with respect to the pyridinium plane, directly attached to the propylene moiety.