Inter- and intramolecular O-H center dot center dot center dot pi hydrogenbonding in the methanol-ethene complex and syn-7-norbornenol, probed by IR, H-1 NMR and quantum chemistry
Lh. Bjerkeseth et al., Inter- and intramolecular O-H center dot center dot center dot pi hydrogenbonding in the methanol-ethene complex and syn-7-norbornenol, probed by IR, H-1 NMR and quantum chemistry, J MOL STRUC, 567, 2001, pp. 319-338
The geometries and energies of syn-7-norbornenol (1) have been investigated
with theoretical and experimental methods, while its epimer anti-7-norborn
enol (2) has been investigated by theoretical methods only. It was found th
at 1 is intramolecularly hydrogen bonded and exists almost exclusively in i
ts hydrogen bonded form, the Anti conformer. Compound 2, for which intramol
ecular hydrogen bonding is impossible, was found to exist as the Gauche con
former. A theoretical investigation of the model complex between methanol a
nd ethene showed that the interaction energy is -3.1 +/- 0.1 kcal mol(-1) (
estimated Hartree-Fock basis set limit plus correlation contribution, not i
ncluding vibrational zero point energy). Electron correlation is essential
in the evaluation of the interaction energy and also for the geometry of th
e complex. It was found that the potential energy surface around the minimu
m energy structure is flat, with an almost freely rotating methanol part. (
C) 2001 Elsevier Science B.V. All rights reserved.