Crystal structure, Hirshfeld surface analysis and PIXEL calculations of a 1:1 epimeric mixture of 3-[(4-nitronenzyiiciene)amino]-2(R,S)-(4-nitrophenyl)-5(S)-(propan-2-yl)imidazolidin-4-one

A 1:1 epimeric mixture of 3-[(4-nitrobenzylidene)amino]-2(R,S)-(4-nitropheny1)-5(S)-(propan-2-yl)imidazolidin-4-one, C19H19N5O5, was isolated from a reaction mixture of 2(S)-amino-3-methyl-1-oxobutanehydrazine and 4-nitrobenzaldehyde in ethanol. The product was derived from an initial reaction of 2(S)-amino3-methyl-l-oxobutanehydrazine at its hydrazine group to provide a 4-nitrobenzylidene derivative, followed by a cyclization reaction with another molecule of 4-nitrobenzaldehyde to form the chiral five-membered imidazolidin-4-one ring. The formation of the five-membered imidazolidin-4-one ring occurred with retention of the configuration at the 5-position, but with racemization at the 2-position. In the crystal, N -H center dot center dot center dot O(nitro) hydrogen bonds, weak C- H center dot center dot center dot O(carbonyl) and C -H center dot center dot center dot O(nitro) hydrogen bonds, as well as C- H center dot center dot center dot pi, N - H center dot center dot center dot pi and pi-pi interactions, are present. These combine to generate a three-dimensional array. Hirshfeld surface analysis and PIXEL calculations are also reported.