Density functional study of the nitrosamine–formic acid and nitrosamine–formamide interactions

During the computation, 15 complexes for nitrosamine–formic acid (Z, E), and nitrosamine–formamide were found. For all of the methods, containing B3LYP/6-311++(2d,2p), B3LYP/aug-cc-pVDZ and B3LYP/aug-cc-pVTZ, the complexes of Z-1 and F-1 are the most stable ones. The order of hydrogen bond strengths are as follows: O–H⋯O > N–H⋯O > N–H⋯N > C–H⋯O > C–H⋯N. Results show that the proton stretching between a donor and an acceptor affects the strength of hydrogen bond. In some cases, eight-member ring is formed due to the resonance-assisted hydrogen bonds (RAHB) mechanism. AIM analyses at the hydrogen bond critical points show maximum electron density (ρ) for O–H⋯O, and minimum electron density for C–H⋯O.