AN ABINITIO STUDY OF THE H2O-MEDIATED 1,3-HYDROGEN REARRANGEMENT IN THE HX-CH=Y(H2O) REVERSIBLE X=CH-YH(H2O) ISOELECTRIC SERIES - X, Y = CH2, NH, OR O

Ab initio calculations are performed to investigate the effect of water on the 1,3-intramolecular hydrogen rearrangement in the HX-CH = Y reversible X = CH-YH isoelectronic series, for X, Y = CH2, NH or O, by modeling with a single H2O molecule. The geometries for the complexes are optimized at both the 3-21G and 6-31G** basis set levels. MP2 and some MP4 calculations are performed to take into account the correlation effects, and ZPV corrections are calculated at the MNDO level. The results show that the water molecule has a significant effect on the molecules in which hydrogen bonds can be formed or partially formed. The "solvent effects" are also examined using the self-consistent reaction-field (SCRF) approach. A combination of supermolecule and SCRF approach appears to work well at predicting the effect of solvent on relative stabilities and barriers.