Carbenen
Carbenen, in chemistry often referred to as carbenes in English, are a class of reactive species characterized by a carbon atom that is divalent and neutral, bearing only six valence electrons. The carbon carries two nonbonded electrons, which can reside in a single orbital (singlet carbene) or as two unpaired electrons in separate orbitals (triplet carbene). This electronic structure makes carbenes highly reactive and, in many cases, short-lived, unless stabilized by substituents or metal coordination.
In terms of state and origin, carbenen can be categorized as free carbenes or metal-associated carbenes. Free
A prominent subdivision arises in organometallic chemistry with Fischer- and Schrock-type carbenen. Fischer carbenen are associated
Applications include catalytic cyclopropanation and C–H or O–H/N–H insertions in synthesis, as well as deployment as