Abstract
The crystal structures of four derivatives of diethyl 2-(((aryl)amino)methylene)malonate (DAM) have been studied by single crystal X-ray diffraction. The molecular structures of all the four derivatives were found to be in co-planar conformation. The detailed analysis of molecular conformation in four derivatives reveals the presence of a common strong intramolecular N–H⋯O hydrogen bonding, forming a ring of graph-set motif S11 (6). The effect of chloro and nitro substitution on their relative strengths of hydrogen bonding are analyzed here. Particularly, in compound 1, additional intramolecular hydrogen bonding between –NO2 and N–H was observed that results in the formation of another six-membered chelate ring. On the other hand in case of compound 3, we have observed type-I Cl⋯Cl interaction for the first time in this class of compounds. Further, Hirshfeld surface has been generated that is mapped with dnorm shape index and curvedness to summarize the weak interactions and examine the molecular shapes in all four derivatives. Effect of nitro (1 and 2) and chloro (3 and 4) substitution on the C⋯H, N⋯O and C⋯O interaction is highlighted in molecular contour and 2D fingerprint plots.