Crystal packing modes of two 1-CH2R-2-methyl-4-nitroimidazoles: Packing with Z′=2

The crystal structures of two similar 1-R-2-methyl-4-nitroimidazoles, where R is allyl (CH2–CH6-point double bond; length half of m-dashCH2, 1) and 2-bromoethyl (CH2–CH2Br, 2) have been determined by means of X-ray crystallography at 100(1) K. In both cases the compounds crystallize with two different (symmetry-independent) molecules in the asymmetric part of the unit cell (Z′=2). The main motifs of crystal packing—molecular tapes—are created by C–H⋯N and strengthened by secondary C–H⋯O hydrogen bonds. The tapes form bilayers via π⋯π interactions. The creation of these bilayers, the primary building blocks of the crystal structures, is possible because two symmetry-independent molecules have different conformations (1) or take part in different intermolecular interactions (2).