Super-electrophilic carbenes and the concept of Philicity

Electron affinities and ionization potentials were calculated for a number of carbenes and compared with the carbene philicity scale mCXY defined by Moss. It is suggested that a two-dimensional rather than a one-dimensional scale is used to classify the carbenes. Examples of extremely electrophilic carbenes with electron affinities above 2 eV are difluorovinylidene with a singlet ground state and 4-oxo-2,3,5,6-tetrafluorocyclohexa-2,5-dienylidene with a triplet ground state. The reactivity of these carbenes towards small molecules under the conditions of matrix isolation is discussed.