Charge Density Distribution and Bond Characterization of 2,2′‐Dipyridylamine (Hdpa): A Combined Study of Experiment and Theory

Abstract

AbstractElectron density distribution of 2,2′‐dipyridylamine (Hdpa) is studied by single‐crystal X‐ray diffraction method at 120 K. Structural determination reveals that the conformation of Hdpa molecule is the syn‐anti conformation caused by the intramolecular N···H‐C hydrogen bond between two pyridine rings. Two Hdpa molecules flock together via two intermolecular N···H‐N hydrogen bonds to form a dimer. Bond characterization is made in terms of deformation density (Δρ), topological analysis of total electron density based on multipole model and molecular orbital (DFT) calculation. The agreement between experiment and theory is good. The topological properties of bond critical points at C‐C, C‐N, N‐H and C‐H bonds are reasonable and reveal a covalent bond character with the high ρ(rc), negative ∇2ρ(rc) and negative total energy density H((rc) values. A low ρ(rc) and positive ∇2ρ(rc) of bond critical points at N···H bonds reveal a closed‐shell interaction for C‐H···N and N‐H···N hydrogen bonds. The π‐delocalization feature around the pyridine ring is also performed by bond ellipticity (ϵ) and fermi‐hole distribution.