Super-electrophilic carbene

Sander applied DFT (B3LYP) theory to carbenic philicity, computing the electron affinities (EA) and ionization potentials (IP) of the carbenes." " The EA tracks the carbene s electrophilicity (its ability to accept electron density), whereas the IP represents the carbene s nucleophilicity (its ability to donate electron density). This approach parallels the differential orbital energy treatment. Both EA and IP can be calculated for any carbene, so Sander was able to analyze the reactivity of super electrophilic carbenes such as difluorovinylidene (9)" which is sufficiently electrophilic to insert into the C—H bond of methane. It even reacts with the H—H bond of dihydrogen at temperamres as low as 40 K, Scheme 7.2) ... 

An advantage of Sander s method is that EA and IP can be calculated for any carbene, and do not depend (as does w xy) 011 specific set of alkenes or carbenes. Thus, Sander is able to examine species he refers to as super-electrophilic carbenes. [82] These include difluorovinylidene, 29 [84] and 4-oxo-2,3,5,6-tetrafluorocyclohexa-2,5-dienylidene, 30, a highly electrophilic triplet carbene. [85] With EA= 2.26 (observed) or 2.56 eV (computed), [84] carbene 29 is electrophilic enough to insert into the C-H bond of methane, and even the H-H bond of hydrogen at temperatures as low as 40 K. This type of reactivity is also observed [85] with 30 (computed EA= 3.61 eV). [82]... 

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