ChemInform Abstract: Electronic Spectra of Jet-Cooled 3-Chlorotropolone. Proton Tunneling in the S1 State

Abstract

The electronic spectra have been measured for jet‐cooled 3‐chlorotropolone in the S1–S0 region to investigate the effect of an asymmetric substitution on proton tunneling in tropolone. Both the 0++ and 0−− transitions have been identified in the fluorescence excitation spectrum, while no 0−+ or 0+− transition has been detected. This suggests that the double minimum potential energy function is almost symmetric for both S1 and S0. The tunneling doublet separations for the origin bands of 3‐chlorotropolone and its OD derivative have been measured to be 23 and 3 cm−1, respectively. These values are very similar to the corresponding values of 19 and 2 cm−1 for tropolone and its OD derivative, indicating that the substitution of a chlorine atom influences only a little on the strength of the intramolecular hydrogen bond.