Crystal structures of hydrazones, 2-(1,3-benzothiazolyl)-NH—N=CH—Ar, prepared from arenealdehydes and 2-hydrazinyl-1,3-benzothiazole

Abstract

Structures of hydrazones, [1: 2-(1,3-benzothiazolyl)-NH—N=CH—C₆H₃—XY], prepared from arenecarbäaldehydes and 2-hydrazinyl-1,3-benzothiazole, are reported. Compounds include unsolvated species, (1: X = 4-Cl, 4-Br, 4-NMe₂; Y = H), [1: X,Y = 2,4-Me₂, 2,4-(OMe)₂], and solvated ones, [(1: X = 4-OH; Y = H) · H₂O], [(1: X = 3-OMe; Y = 4-OH) · H₂O], and [(1: X = 2-OH; Y = 5-NO₂) · DMSO]. The solvated compound, [(1: X = 2-OH; Y = 5-NO₂) · DMSO], exists in the imino form in contrast to the (E)-2-(1,3-benzothiazolyl)-NH—N=CH—Ar form exhibited by the other compounds. Common intermolecular interactions in the non-solvated compounds, (1: X = 4-Cl, 4-Br, 4-NMe₂; Y = H) and [1: X,Y = 2,4-Me₂, 2,4-(OMe)₂], are strong dimer forming N—H · · · N hyädrogen bonds and weaker π · · · π interactions. The latter involve the benzothazole rings, except in [1: X,Y = 2,4-(OMe)₂], where the π · · · π interactions involve thiazole and C₆H₃(OMe)₂ rings. The dimer forming N—H · · · N intermolecular hydrogen bonds and π · · · π stacking interactions persist in the hydrate, [(1: X = 3-OMe; Y = 4-OH) · H₂O], but not in the other solvates, [(1: X = 4-OH; Y = H) · H₂O] and [(1: X = 2-OH; Y = 5-NO₂) · DMSO]. For [(1: X = 4-OH; Y = H) · H₂O], the important direct links between [(1: X = 4-OH; Y = H) are chain forming O—H · · · N hydrogen bonds, supplemented by π · · · π interactions. For all solvated compounds, the solvate molecules are involved in indirect links between the hydrazone molecules. In the case of [(1: X = 2-OH; Y = 5-NO₂) · DMSO], present in the imino form, a network of rings is generated from the hydrogen bonding interactions of the DMSO solvate with the N—H and N—O(nitro) moieties of (1: X = 2-OH; Y = 5-NO₂).