Ab initio theoretical and matrix isolation experimental studies of hydrogen bonding: evidence of a dramatic effect of the matrix on the structure and vibrational spectrum of HBr:3,5-dichloropyridine

Ab initio calculations at the MP2/6–31 + G(d,p) level of theory have been carried out to determine the structure and vibrational spectrum of two hydrogen-bonded complexes, HBr:3,5-dichloropyridine and HBr:3,5-dichloropyridine:2Ne. The presence of the two Ne atoms leads to dramatic structural and spectral changes. The computed HBr:3,5-dichloropyridine:2Ne spectrum exhibits strong low-frequency bands, in agreement with the experimental spectrum of HB:3,5-dichlropyridine obtained in an Ar matrix.