4-Oxo-2,3,5,6-tetrafluorocyclohexa-2,5-dienylidene--a highly electrophilic triplet carbene.
The 4-oxocyclohexa-2,5-dienylidenes are an interesting class of highly electrophilic carbenes. We investigated the reactivity of the 2,3,5,6-tetrafluorinated and -tetrachlorinated derivatives 1b and 1c with small molecules under conditions of matrix isolation. The reactions with molecular oxygen and with carbon monoxide produce the expected carbonyl O-oxides and ketenes, respectively. As a result of the extreme electrophilicity of 1b and c both carbenes insert with no or very small activation barriers into H2 or the CH bonds of hydrocarbons. Obviously, spin restrictions for these formally spin-forbidden reactions do not result in substantial thermal activation barriers.
Sander
W
W
Lehrstuhl für Organische Chemie II der Ruhr-Universität, Bochum, Germany. sander@xenon.orch.ruhr-uni-bochum.de
Hübert
R
R
Kraka
E
E
Gräfenstein
J
J
Cremer
D
D