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

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 bot h the triplet excited state and the ketyl radical. Vibrational spectral ass ignments were made for all the intermediate states. Based on the analysis o f the spectra, it was concluded that the enhanced reactivity towards hydrog en 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. Copyright (C) 2000 John Wil ey & Sons, Ltd.