Effect of Substituents on Molecular Geometry and Self-Aggregation in the Crystal Structures of Ethylenediamine-N,N,N‘,N‘-tetraamides

Abstract

The derivatives of ethylenediamine-N,N,N‘,N‘-tetraamides were prepared, and their crystal structures were analyzed in order to understand the variations in their molecular and supramolecular geometries with respect to the substituents. The crystal structures of these compounds indicated that these moieties can exhibit four types of molecular geometries. These geometries contain a minimum of two intramolecular N−H···N hydrogen bonds between the amine N-atom and N−H group of the amide. The p-bromophenyl, p-chlorophenyl, 3-pyridyl, and 4-pyridyl derivatives exhibit H-shape geometry, p-iodophenyl, p-toloyl, and 4-pyridyl derivatives exhibit similar geometrical shape, the 4-pyridyl derivative exhibited the geometry of the Greek character π, and the benzyl derivative exhibited the geometry of a swastika. Among the halogen derivatives, the iodo derivative was found to behave differently from bromo and chloro derivatives. The amide-to-amide hydrogen bonds between the iodo-substituted molecules were sacrificed in favor of inclusion of DMF.