In chemistry, a carbene is a highly reactive organic molecule containing a carbon atom with six valence electrons and having the general formula: R1R2C: (two substituents and two electrons). There are two kinds of carbenes: singlets and triplets. The carbon atoms of singlets are sp2-hybridised, with one empty p-orbital crossing the plane containing R1, R2, and the free electron pair. Such molecules are generally very short lived, although persistent carbenes are known. The prototypical carbene… (More on Carbene)