Crystal and molecular structure of 4-acetylamino-2-bromo-5-isopropyl-1-methylimidazole

Abstract

The molecular and crystal structure of 4-acetylamino-2-bromo-5-isopropyl-1-methylimidazole, C₉H₁₄BrN₃O, has been determined by single-crystal X-ray diffraction methods. The compound crystallizes in space group P2₁2₁2₁, a= 9·465 ± 0·003, b= 13·310 ± 0·004, and c= 9·111 ± 0·002 Å, with Z= 4. Intensity data were collected on a Picker automatic diffractometer and the structure was solved by the heavy atom method. Least-squares refinement assuming anisotropic temperature factors converged to a discrepancy index of 6·1% for 1057 reflections above background. The heterocyclic ring is found to be planar with the acetylamino-group forming a dihedral angle of nearly 90° with the plane. Evidence that severe steric crowding occurs between the substituents is apparent from the conformations of these groups, from the external bond angles at the ring, and from certain non-bonded interatomic distances.