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A detailed structural analysis of the benzimidazole nitroarenes 1‐(4‐nitrophenyl)‐1H‐1,3‐benzimidazole, C13H9N3O2, (I), 1‐(4‐nitrophenyl)‐2‐phenyl‐1H‐1,3‐benzimidazole, C19H13N3O2, (II), and 2‐(3‐methylphenyl)‐1‐(4‐nitrophenyl)‐1H‐1,3‐benzimidazole, C20H15N3O2, (III), has been performed. They are nonplanar structures whose crystal arrangement is governed by Csp2—H…A (A = NO2, Npy and π) hydrogen bonding. The inherent complexity of the supramolecular arrangements of compounds (I) (Z′ = 2) and (II) (Z′ = 4) into tapes, helices and sheets is the result of the additional participation of π– and n–π* (n = O and Npy; π* = Csp2 and ) interactions that contribute to the stabilization of the equi‐energetic conformations adopted by each of the independent molecules in the asymmetric unit. In contrast, compound (III) (Z′ = 1) is self‐paired, probably due to the effect of the steric demand of the methyl group on the crystal packing. Theoretical ab initio calculations confirmed that the presence of the arene ring at the benzimidazole 2‐position increases the rotational barrier of the nitrobenzene ring and also supports the electrostatic nature of the orthogonal ONO…Csp2 and Npy…NO2 interactions. [ABSTRACT FROM AUTHOR]

Two new molecular structures, namely 1,3-bis(trimethylsilyl)-1 H-benzimidazole-2(3 H)-thione, C13H22N2SSi2, (2), and 1-trimethylsilyl-1 H-benzimidazole-2(3 H)-thione, C10H14N2SSi, (3), are reported. Both systems were derived from 1 H-benzimidazole-2(3 H)-thione. Noncovalent C-H...π interactions between the centroid of the benzmidazole system and the SiMe3 groups form helicoidal arrangements in (2). Dimerization of (3) results in the formation of R22(8) rings via N-H...S interactions, along with parallel π-π interactions between imidazole and benzene rings. [ABSTRACT FROM AUTHOR]

The title compound, C12H13NO4, is one of the few examples that exhibits a syn conformation between the amide and ester carbonyl groups of the oxalyl group. This conformation allows the engagement of the amide H atom in an intramolecular three-centred hydrogen-bonding S(6) S(5) motif. The compound is self-assembled by C=O...C=O and amide-π interactions into stacked columns along the b-axis direction. The concurrence of both interactions seems to be responsible for stabilizing the observed syn conformation between the carbonyl groups. The second dimension, along the a-axis direction, is developed by soft C-H...O hydrogen bonding. Density functional theory (DFT) calculations at the B3LYP/6-31G(d,p) level of theory were performed to support the experimental findings. [ABSTRACT FROM AUTHOR]