Intermolecular hydrogen abstraction from triplet excited state of decafluorobenzophenone: a Raman investigation

Abstract

The influence of the structure of the triplet excited state of benzophenone (bp) and decafluorobenzophenone (dfbp) on the reactivity towards hydrogen abstraction was studied by time-resolved resonance Raman spectroscopy. The resonance Raman spectra and Raman excitation profiles were recorded for both the triplet excited state and the ketyl radical. Vibrational spectral assignments were made for all the intermediate states. Based on the analysis of the spectra, it was concluded that the enhanced reactivity towards hydrogen atom abstraction of dfbp over bp is due to (a) the non-planar structure of the triplet excited state of dfbp, thus increasing the accessibility for the CO group, and (b) the highly polarized and electrophilic nature of the CO group in the triplet excited state of dfbp.