Mv. Vener et S. Scheiner, HYDROGEN-BONDING AND PROTON-TRANSFER IN THE GROUND AND LOWEST EXCITEDSINGLET-STATES OF O-HYDROXYACETOPHENONE, Journal of physical chemistry, 99(2), 1995, pp. 642-649
The potential energy surface of the ground stare and lowest lying sing
let of o-hydroxyacetophenone was calculated at the ab initio SCF and C
IS levels, respectively, using a split-valence basis set to which was
added polarization functions on atoms involved in the intramolecular H
-bond. Whereas these potentials each contain one minimum corresponding
to the normal form and a second well for the proton-transferred tauto
mer, only one minimum appears in these potentials after correlation is
added. S-0 --> S-1 excitation hence induces the tautomerization assoc
iated with intramolecular proton transfer from the hydroxyl to the car
bonyl oxygen. The excited state proton transfer may involve a nonradia
tive transition from the S-1(n pi) state to S-1(pi pi*). The vibratio
nal spectra of the two tautomers have certain strong differences. Anha
rmonic adiabatic treatment of the OH...O segment of the molecule leads
to improved reproduction of experimentally observed nu(O...O) and nu(
OH) frequencies.