Carbenes can be stabilised as organometallic species. These transition metal carbene complexes fall into two categories:
* Fischer carbenes in which carbenes are tethered to a metal and an electron-withdrawing group (usually a carbonyl),
* Schrock carbenes; in which carbenes are tethered to a metal and an electron-donating group. The reactions that such carbenes participate in are very different from those in which organic carbenes participate.