Experimental and computational evidence for stabilising parallel, offset π[C(=O)N(H)N=C]...π(phenyl) interactions in acetohydrazide derivatives

Parallel, offset pi[C(= O)N(H)N = C]...pi(phenyl) interactions are observed in the crystal of (2-thienyl)CH2CON(H)-N.C(H)Ph, along with more conventional non-covalent interactions. All notable interactions were analysed using Hirshfeld surface analysis, NCI plots and QTAIM analysis. The pi[C(= O)N(H)N = C]...pi(phenyl) interactions, whereby the N(H) atom lies over the ring centroid and the N and C atoms on either side of the N(H) atom closely overlay the 1,3-carbon atoms of the phenyl ring, are shown to be attractive. Theory suggests the energy of association provided by the pi[C(= O)N(H)N = C]...pi(phenyl) interaction to the molecular packing to be about 15 kJ mol(-1), a value similar to that provided by similarly oriented benzene and pyridine rings. A survey of related structures in the literature suggests that comparable interactions occur in approximately 5-6% of crystals where they can potentially occur.