Different mol-ecular conformations in the crystal structures of three 5-nitro-imidazolyl derivatives.

The crystal structures of ()-1-methyl-5-nitro-1-imidazole-2-carbaldehyde -benzyl-oxime, CHNO, (I), ()-1-methyl-5-nitro-1-imidazole-2-carb-alde-hyde -(4-fluoro-benz-yl) oxime, CHFNO, (II), and ()-1-methyl-5-nitro-1-imidazole-2-carbaldehyde -(4-bromo-benz-yl) oxime, CHBrNO, (III), are described. The dihedral angle between the ring systems in (I) is 49.66 (5)° and the linking N-C-C=N (m = methyl-ated) bond shows an conformation [torsion angle = 175.