1-Benzyl-3-[(trimethyl-sil-yl)meth-yl]benzimidazolium chloride monohydrate.

The title compound, C(18)H(23)N(2)Si(+)·Cl(-)·H(2)O, was synthesized from 1-[(trimethyl-sil-yl)meth-yl]benzimidazole and benzyl chloride in dimethyl-formamide. The benzimidazole ring system is approximately planar, with a maximum deviation of 0.022 (2) Å, and makes an angle of 74.80 (12)° with the phenyl ring. The crystal packing is stabilized by O-H⋯Cl, C-H⋯Cl, C-H⋯O and C-H⋯π inter-actions between symmetry-related mol-ecules together with π-π stacking inter-actions between the imidazolium and benzene rings [centroid-centroid distance = 3.5690 (15) Å] and between the benzene rings [centroid-centroid distance = 3.7223 (14) Å].