Theoretical and NMR studies of deuterium isotopic perturbation of hydrogen bonding in symmetrical dihydroxy compounds.

摘要: Deuterium equilibrium isotope effects (EIEs) for a cage diol and 2,6-dihydroxyacylaromatics complexes thereof containing intra- or intermolecular hydrogen bonds have been calculated using harmonic anharmonic vibrational frequencies Gaussian ’03 the HF, B3LYP, MP2 levels of theory. The predicted compared with experimental NMR data, origins characterized in terms zero-point energy differences enthalpic entropic contributions to free difference between labeled species. Reliable predictions based upon were found systems whose are governed by bond stretching determined low-frequency modes. In contrast, thermochemical be far less consistent. Vibrational entropy is play an important role modulating an...