Synthesis and structural characterization of 1-butyl-2,3-dimethylimid- azolium bromide and iodide

Abstract

1-Butyl-2,3-dimethylimidazolium bromide {(bdmim)Br} (1) and iodide {(bdmim)I} (2) were prepared conveniently by the reaction of 1,2-dimethylimidazole and the corresponding 1-halobutane. The compounds were characterized by 1H and 13C{1H} NMR spectroscopy as well as by X-ray single crystal crystallography. 1 crystallizes in the monoclinic crystal system, space group P21/n, with Z = 4, and unit cell dimensions a = 8.588(2), b = 11.789(1), c = 10.737(2) Å, β= 91.62(3)°. Compound 2 crystallizes in the monoclinic crystal system, space group P21/c, with Z = 8, and unit cell dimensions a = 10.821(2), b = 14.221(3), c = 15.079(2) Å, β= 90.01(3)°. The lattices of the salts are built up of 1-butyl-2,3-dimethylimidazolium cations and halide anions. The cations of 1 form a double layer with the imidazolium rings stacked together due to n interactions. The Br- anions lie approximately in the plane of the imidazolium ring, and the closest interionic Br⋯H contacts span a range of 2.733(1) - 2.903(1) Å. Compound 2 shows no π stacking interactions. The closest interionic I⋯H contacts are 2.914(1)-3.196(1)Å. © 2007 Verlag der Zeitschrift für Naturforschung.