Definition of Carbene

In chemistry, a carbene is a highly reactive organic molecule with a divalent carbon atom with only six valence electrons and the general formula: R¹R²C: (two substituents and two electrons). The carbene comes in two varieties: a singlet and triplet. The singlet type has its carbon atom sp² hybridised with an empty p-orbital extending above and below a plane containing R¹ and R² and the free electron pair. Typically these molecules are very short lived, although persistent carbenes are now known.