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

ABSTRACT: The crystal structures of (E)-1-methyl-5-nitro-1H-imidazole-2-carbaldehyde O-benzyl-oxime, C12H12N4O3, (I), (E)-1-methyl-5-nitro-1H-imidazole-2-carb-alde-hyde O-(4-fluoro-benz-yl) oxime, C12H11FN4O3, (II), and (E)-1-methyl-5-nitro-1H-imidazole-2-carbaldehyde O-(4-bromo-benz-yl) oxime, C12H11BrN4O3, (III), are described. The dihedral angle between the ring systems in (I) is 49.66?(5)° and the linking Nm-C-C=N (m = methyl-ated) bond shows an anti conformation [torsion angle = 175.00?(15)°]. Compounds (II) and (III) are isostructural [dihedral angle between the aromatic rings = 8.31?(5)° in (II) and 5.34?(15)° in (III)] and differ from (I) in showing a near-syn conformation for the Nm-C-C=N linker [torsion angles for (II) and (III) = 17.64?(18) and 8.7?(5)°, respectively], which allows for the occurrence of a short intra-molecular C-H?N contact. In the crystal of (I), C-H?N hydrogen bonds link the mol-ecules into [010] chains, which are cross-linked by very weak C-H?O bonds into (100) sheets. Weak aromatic ?-? stacking inter-actions occur between the sheets. The extended structures of (II) and (III) feature several C-H?N and C-H?O hydrogen bonds, which link the mol-ecules into three-dimensional networks, which are consolidated by aromatic ?-? stacking inter-actions. Conformational energy calculations and Hirshfeld fingerprint analyses for (I), (II) and (III) are presented and discussed.

SUBMITTER: Osorio LFB 

PROVIDER: S-EPMC5947808 | biostudies-other | 2018 Mar

REPOSITORIES: biostudies-other