DFT prediction of anomalously large blue shift of the C-H stretching frequency in 2-vinyloxypyridine and -quinoline due to the intramolecular C-H···N hydrogen bonding

B3LYP/++6-311G(2d,p) calculations predict that the vinyl group C-H stretching frequency in 2-vinyloxypyridine and -quinoline is blue shifted by as much as 60-70 cm−1 due to the intramolecular C-H⋯N hydrogen bond. The blue shift is accompanied by a two-fold enhancement of the C-H absorption band intensity, this behavior being counter to the typical intermolecular hydrogen bonding effects.