Crystal structures and Hirshfeld surfaces of differently substituted (E)-N′-benzylidene-N-methyl-2-(thiophen-2-yl)acetohydrazides

Abstract

The syntheses and crystal structures of (E)-N′-(3-cyanobenzylidene)-N-methyl-2-(thiophen-2-yl)acetohydrazide, C15H13N3OS, (I), and (E)-N′-(4-methoxybenzylidene)-N-methyl-2-(thiophen-2-yl)acetohydrazide, C15H16N2O2S, (II), with different substituents in the meta and para position of the benzene ring are described. Compounds (I) and (II) both crystallize with two molecules in the asymmetric unit, with generally similar conformations [r.m.s. overlay fits for (I) and (II) of 0.334 and 0.280 Å, respectively] that approximate to L-shapes. The thiophene rings in (I) are well ordered, whereas those in (II) exhibit `flip' rotational disorder [occupancies 0.662 (2) and 0.338 (2) for molecule 1, and 0.549 (3) and 0.451 (3) for molecule 2]. The packing for (I) features short C—H...O interactions arising from the C—H grouping adjacent to the cyanide group and C—H...Nc (c = cyanide) links arising from the methine groups to generate [110] double chains. Weak C—H...π interactions interlink the chains into a three-dimensional network. The packing for (II) features numerous C—H...O and C—H...π interactions arising from different donor groups to generate a three-dimensional network. Hirshfeld fingerprint plots indicate significant differences in the percentage contact surfaces for (I) and (II).

Keywords

• crystal structure
• carbohydrazide
• methylation
• weak hydrogen bonds