Singlet-Triplet Interconversion of Diphenylmethylene Energetics, Dynamics and Reactivities of Different Spin States

摘要

A combination of picosecond and nanosecond laser spectroscopy measurements, chemical quenching experiments and triplet sensitization experiments has allowed the determination of the rapid singlet to triplet and slower triplet to singlet intersystem crossing rates for diphenylmethylene in fluid solution at room temperature. It is shown that under the conditions of the kinetic measurements, singlet and triplet diphenylmethylene (1DPM and 3 DPM, respectively) are in rapid eqilibrium relative to reactions, so that knowledge of the values of k sub st and k sub st allows determination of the equilibrium constant and change in free energy for the 1DPM in equilibrium with DPM process. The absolute reactivity of 1DPM toward a series of alcohols has been determined and is discussed in terms of other current investigations of carbene reactivity. (Reprints)