Intramolecular NH⋯O resonance-assisted hydrogen bonds in crystal structures of oxaphosphinanes and chromones—DFT calculations and AIM analysis

The intramolecular NH⋯O resonance-assisted hydrogen bonds in crystal structures of oxaphosphinanes and chromones are investigated. The molecular structures of these compounds were taken from X-ray crystal structures and further used to perform theoretical calculations at B3LYP/6-311++G(d,p) level. The geometrical parameters of NH⋯O intramolecular H-bonds were analyzed. The ‘atoms in molecules’ theory was also applied to get the more precise insight into the nature of such H-bond interactions. The bond critical points and the ring critical points were determined and their characteristics were also analyzed.