RESUMEN
The experimental charge density distribution was determined for 2-methyl-4-nitro-1-phenyl-1H-imidazole-5-carbonitryle, using the Hansen-Coppens multipole model. Free R factor calculations were performed with MoPro software to find optimal restraints for a physically meaningful model. The crystal packing is determined to some extent by weak C-H···O and C-H···N hydrogen bonds but mostly by a lateral electrostatic interaction between antiparallel side-by-side C≡N groups. Electrostatic energy calculations were performed based on the experimental data and are in line with the high-level, explicitly correlated theoretical SCS-RI-MP2-F12 calculations of total energy. The molecular dipole moment and atomic charge values were compared for different experimental and theoretical models, to highlight the dependence of the electrostatic property outputs on the applied restraints. Interesting O···O contacts are also described. The results are compared with two recently investigated nitroimidazole derivatives, namely, 1-(2'-aminophenyl)-2-methyl-4-nitroimidazole and 1-phenyl-4-nitroimidazole.