Abstract: Quantum chemistry ab initio methods were applied to study the blue-and red-shifted H-bonds between HNO and (HF)1≤n≤shifts were caused by repolarization, rehybridization, and intramolecular hyperconjugation. All of the X…H—F (X=O, N, F) are red-shifted, and intermolecular hyperconjugation led to the red shifts. In these chains of H-bonds, the variations of intermolecular hyperconjugations, electron densities at the bond critical points (BCPs), and strengths and frequency shifts of the H-bonds were correlated with each other by definite rules.

Key words: Blue-shifted hydrogen bond, Electron density topology analysis, Intermolecular and intramolecular hyperconjugation, Rehybridization