2-Methyl-4-nitro-1-phenylimidazole and 2-Methyl-1-(p-methylphenyl)-4-nitroimidazole

Abstract

None of the compounds has H atoms which are able to form hydrogen bonds. Neither the imidazole nor the phenyl rings are stacked. The aromaticity indices 15 (Bird, 1985) and HOMA (Gdaniec, Turowska-Tyrk & Krygowski, 1989) are 67.9 and 0.823, respectively for unsubstituted imidazole [structural data for these calculations are from McMullan, Epstein, Ruble & Craven (1979)]. [Note that in the original publication (Bird, 1985), 15 for imidazole is calculated from data corrected for libration and is 64.] The title compounds have smaller values: 61.3 and 0.565 for (I) and 64.2 and 0.664 for (II). The observed angles between the least-squares planes of the imidazole and phenyl rings are similar to those found in other 1-arylimidazoles (Ishihara et al., 1992) and represent the compromise between the crystal packing and the minimum energy position, which was found by MOPAC (Quantum Chemistry Program Exchange No. 455) calculations at 90 ° (using default settings; rotation of the phenyl group around the N1--C4 bond with C5 and C9 related by symmetry). AbstractThe two title compounds, CIoH9N302, (I), and CllHll-N302, (II), are monomers. No intermolecular interactions are observed. The angle between the planes of the phenyl and imidazole rings is 51.2 (6) in (I) and 53.9 (5) ° in (lI). The nitro groups are twisted with respect to the imidazole tings by 3.2 (5) and 3.7 (5) ° in (I) and (II), respectively.

2-Methyl-4-nitro-1-(3-pyridyl)-1H-imidazole

“…This is a part of our studies of intermolecular interactions in 4nitroimidazole derivatives that started with 1-phenyl-4-nitroimidazole (Kubicki et al, 2001(Kubicki et al, , 2002. Similar packing schemes and unit-cell parameters were found for 1-phenyl-and 1-(pmethylphenyl)-2-methyl-4-nitroimidazole (Kowalski, 1995). For related literature, see: Suwiń ski & Szczepankiewicz (1991).…”

“…Data collection: CrysAlis CCD (Oxford Diffraction, 2002); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Stereochemical Workstation Operation Manual (Siemens, 1989); software used to prepare material for publication: SHELXL97. Almost identical crystal packing was observed in the crystal structure of 1-(4-methylphenyl)-2-methyl-4-nitroimidazole (Kowalski, 1995), which crystallizes in similar unit cell (8.259 (2) Å, 7.805 (2) Å, 16.774 (3) Å). Also, there are close analogies between the intermolecular contacts in these structures.…”

“…Also, there are close analogies between the intermolecular contacts in these structures. Another similar unit cell was used to describe 1phenyl-2-methyl-4-nitroimidazole (Kowalski, 1995). In this case, however, only the projection along b-direction might be compared to the former cases; the packing along other directions looks quite different.…”

Infrared spectrum and UV-induced photochemistry of matrix-isolated 5-methoxy-1-phenyl-1H-tetrazole

“…The inter-ring angle is determined by the balance between three main factors: (i) conjugation of the electron systems of both rings, which favors their coplanarity; (ii) steric repulsion between the substituents on the tetrazole ring, which favors a non-planar geometry; and (iii) intramolecular H-bond-like interaction between the ortho-hydrogen atoms of the phenyl ring and O 17 or N 2 atoms (H 12 · · ·N 2 and H 16 · · ·O 17 interactions can be expected to favor non-coplanar and coplanar arrangements of the two rings, respectively). In view of the accumulated data on several molecules with two rings connected by a single bond (e.g., 2-phenylpyridine, 2phenylimidazole, 1-methyl-2-phenylimidazole, 4,6-dichloro-2methylthio-5-phenylpyrimidine and several phenyl-substituted members of the tetrazole family [15,[32][33][34][35][36][37][38][39][40][41][42][43]), among those three effects, the second appears to be the dominant one. Indeed, it has been demonstrated that the size of the sterically interacting substituents in the two rings is determinant on the relative orientation of the rings [15,[32][33][34][35][36][37][38][39][40][41][42][43].…”

1-(p-Methoxyphenyl)-2-methyl-4-nitroimidazole and 1-(p-Acetylphenyl)-2-methyl-4-nitroimidazole

“…As part of a study of radiosensitizing nitroimidazoles (Suwiriski & Salwiriska, 1982) and a continuation of studies presented recently (Kowalski, 1995), the crystal structures of 1-(p-methoxyphenyl)-2-methyl-4-nitroimidazole, (I), and 1-(p-acetylphenyl)-2-methyl-4-nitroimidazole, (II), have been determined.…”