[:pb]Different packing motifs of isomeric ( )- –(halophenylmethylidene)- -methyl-2-(thiophen-2-yl)acetohydrazides controlled by C-H…O interactions[:]

[:pb]Authors: Cardoso, L. N. F.; Nogueira, T. C. M.; Wardell, J. L.; De Souza, M. V. N.; Harrison, W. T. A.
Source: Acta Crystallographica Section e, Crystallographic Communications, v. 74, p. 313-318, 2018
Publisher: Science Direct

Abstract

The crystal structures of three isomeric (E)-N′-(chloro­phenyl­methyl­idene)-N-methyl-2-(thio­phen-2-yl)acetohydrazides (C₁₄H₁₃ClN₂OS) are described, with the Cl atom in ortho (I), meta (III) and para (IV) positions in the benzene ring. The ortho-bromo derivative (II) (C₁₄H₁₃BrN₂OS), which is isostructural with its chloro congener (I), is also reported. Mol­ecules (I)–(III) have similar conformations, which approximate to L-shapes, as indicated by their N—C—C—C_t (t = thio­phene) torsion angles of −90.1 (3), −91.44 (18) and −90.7 (9)°, respectively. The conformation of (IV) is different, with an equivalent torsion angle of −170.75 (11)° corresponding to a more extended shape for the mol­ecule. The thio­phene ring in each structure features `flip’ rotational disorder. The packing for (I) and (II) features inversion dimers, linked by pairs of C—HO inter­actions, which generate R₂²(14) loops. In the crystal of (III), [010] C(8) chains arise, with adjacent mol­ecules linked by pairs of C—HO hydrogen bonds. The packing for (IV) features unusually short C—HO inter­actions arising from an H atom attached to the benzene ring (HO = 2.18 Å), which lead to C(9) [301] chains. Hirshfeld fingerprint percentage contact contributions are similar for the four title compounds.

Keywords: crystal structure,carbohydrazide,methyl­ation,weak hydrogen bonds

Document Type: Research Article

DOI: 10.1107/S2056989018001251

Publication date: Março de 2018[:]