Synthesis and crystal structures of 2-bromo-1,3-di-methyl-imidazolium iodides.

Attempts at direct bromination of 1,3-di-methyl-imidazolium salts were futile. The title compounds, 2-bromo-1,3-di-methyl-imidazolium iodide chloro-form 0.33-solvate, C5H8BrN2+·I-·0.33CHCl3, 2-bromo-1,3-di-methyl-imidazolium iodide di-chloro-methane hemisolvate, C5H8BrN2+·I-·0.5CH2Cl2, and 2-bromo-1,3-di-methyl-imidazolium iodide hemi(diiodide), C5H8BrN2+·I-·0.5I2, were obtained by methyl-ation of 2-bromo-1-methyl-imidazole. They crystallized as CHCl3, CH2Cl2 or I2 solvates/adducts. The Br atom acts as a σ-hole to accept short C-Br⋯I inter-actions. C-H⋯I hydrogen bonds are observed in each structure.