Car–Parrinello and path integral molecular dynamics study of the intramolecular hydrogen bond in the novel class of anionic H-chelates: 6-Nitro-2,3-dipyrrol-2-ylquinoxaline anion

摘要: Abstract Theoretical studies of the structure and proton motion in intramolecular N–H⋯N hydrogen bond 6-nitro-2,3-dipyrrol-2-ylquinoxaline anion were carried out at DFT, MP2 molecular dynamics levels. Geometry optimization 6-311++G(2d,2p) level demonstrate existence two tautomers on potential energy surface. The difference between both is equals 1.62 (1.42) kcal/mol. Dynamics was investigated vacuum 233 K using Car–Parrinello path integral dynamics. Very large delocalization bridging noted especially simulation. DFT calculated coupling constant across 16.5 Hz good agreement with experimental value.