Time-resolved EPR measurements and semi-empirical MO calculations have been carried out to clarify the electronic structure of the T1 state of nonphosphorescent tropolone. The observed zero-field splitting parameters indicate that the T1 state has a pure ππ* character and the energy order among the spin sublevels was Tγ (in-plane) > Tx (in-plane) > 0 > Tz (out-of-plane), which is the same as tropone for a parent molecule. However, the principal X-axis slightly turns out of the carbonyl bond direction so that the intersystem crossing from the S1 state to the Tγ sublevel becomes more active. The spin densities obtained from hyperfine splittings of protons and MO calculation of AM1 method show an asymmetric distribution of unpaired π-electrons over two oxygens as well as the seven-membered ring. This unbalanced distribution makes the deviation of the X-axis from the carbonyl bond clear. We found two sites that can exchange each other by intramolecular proton transfer in a durene single crystal.
|Number of pages||5|
|Journal||Journal of the Chemical Society - Faraday Transactions|
|Publication status||Published - 1998 Jan 1|
ASJC Scopus subject areas
- Physical and Theoretical Chemistry