Super‐electrophilic carbenes and the concept of Philicity

4-Oxo-2,3,5,6-tetrafluorocyclohexa-2,5-dienylidene—A Highly Electrophilic Triplet Carbene

“…Since the ªphilicityº of carbenes as defined by Moss [40,41] is difficult to determine for strongly electrophilic carbenes and only defined for singlet groundstate carbenes, the electron affinities EA can be used as a measure of the carbene philicity. [42] In a few cases EAs of carbenes are known experimentally, and it has been shown that EAs can be calculated reliably at the B3LYP level of theory by means of a large basis set (6-311 G(d,p)). [43] EAs of carbenes 1 a ± c were determined as 2.05, 3.32, and 3.08 eV, [42] indicating a large gap between the halogenated carbenes and 1 a.…”

“…[42] In a few cases EAs of carbenes are known experimentally, and it has been shown that EAs can be calculated reliably at the B3LYP level of theory by means of a large basis set (6-311 G(d,p)). [43] EAs of carbenes 1 a ± c were determined as 2.05, 3.32, and 3.08 eV, [42] indicating a large gap between the halogenated carbenes and 1 a. However, at 2.05 eV the electron affinity of 1 a is still larger than that of (singlet) phenylchlorocarbene (1.52 eV) or (triplet) diphenylcarbene (1.48 eV), a fact that underlines the strongly electrophilic character of oxocyclohexadienylidenes 1.…”

Ligand properties of N-heterocyclic and Bertrand carbenes: A density functional study

“…In addition to DN, v alone can be used as a measure of the nucleophilicity of carbenes. Sander et al [40] have shown that nucleophilic carbenes are characterized by low IP and low EA; in contrast, electrophilic carbenes have high IP and high EA. It was thus suggested by Sander et al that electrophilicity of a carbene is proportional to v. We will use both quantities, DN and v in our analysis of the electrophilicity/nucleophilicity of carbenes.…”

The Bromodiazirinyl Anion: A Weakly Bound Complex of Diazirinylidene and a Bromide Ion

“…EA ≈ –0.5 eV (Figure 4). 18 The high IP and EA of 4 are more features it shares with fluorocarbenes (for CF 2 , calcd. IP = 12.3 eV, EA = 0.0 eV; for CFCl, calcd.…”