Variation in supramolecular arrangements of hydrazones, o-H2NC6H4CMe=NNHC6H4X (X = H, o-, m- and p-NO2), derived from o-aminoacetophenone and phenylhydrazines

The crystal structures of four hydrazones, 1, derived from phenylhydrazines, XC6H4NHNH2 (Xdouble bond; length as m-dashH, o-NO2, m-NO2 or p-NO2) with 2-aminoacetophenone are reported, as is the mono hydrochloride, (2: Xdouble bond; length as m-dashm-NO2), of (1: Xdouble bond; length as m-dashm-NO2). Consistent strong intramolecular hydrogen bonds in 1 are of the type, Nsingle bondH(amino)⋯N(hydrazono), while (1: Xdouble bond; length as m-dashm-NO2) portrays an additional Nsingle bondH(hydrazono)⋯O(nitro), intramolecular hydrogen bond. Of interest, different sets of strong intermolecular interactions are found even among the nitro derivatives, 1. In (1: Xdouble bond; length as m-dasho-NO2), the strongest intermolecular interactions are Nsingle bondH(amino)⋯O(nitro) hydrogen bonds, while in (1: Xdouble bond; length as m-dashm-NO2 and p-NO2), both Nsingle bondH(hydrazono)⋯O(nitro) and Nsingle bondH(amino)⋯N(amino) are present. These strong intermolecular hydrogen bonds coupled with different combinations of some of Csingle bondH⋯O, πsingle bondπ stacking interactions and Nsingle bondO⋯π generate different supramolecular arrays for (1: X = nitro): 2-D, 2-D and 3-D, respectively for (1: Xdouble bond; length as m-dasho-NO2), for (1: Xdouble bond; length as m-dashm-NO2) and (1: Xdouble bond; length as m-dashp-NO2). In (1: Xdouble bond; length as m-dashH), the major intermolecular interactions are Nsingle bondH(hydrazono)⋯N(amino hydrogen bonds: these, supplemented by weaker Nsingle bondH⋯π and Csingle bondH⋯π interactions, generate a two-dimensional array.

While significant changes in the intermolecular interactions result on formation of the salt, (2: Xdouble bond; length as m-dashm-NO2) from (1: Xdouble bond; length as m-dashm-NO2), the strong Nsingle bondH(amino)⋯N(hydrazono) intramolecular hydrogen bonds persist. Strong intermolecular hydrogen bonds found in (2: Xdouble bond; length as m-dashm-NO2) are of the types Nsingle bondH⋯Cl (both hydrazone and amine), Nsingle bondH(amino)⋯O(nitro): these coupled with weaker Csingle bondH⋯O, Nsingle bondO⋯π, and πsingle bondπ generate a three dimensional array.