Carbyne
doublet (1 radical, 1 pair, 1 vacant orbital)
quartet (3 radicals)
In organic chemistry, a carbyne is a general term for any compound whose structure consists of an electrically neutral carbon atom connected by a single covalent bond and has three non-bonded electrons. The carbon atom has either one or three unpaired electrons, depending on its excitation state; making it a radical. The chemical formula can be written R−C· or R−C3· (also written as ⫶C−R), or just CH.
Carbynes can be seen as derivatives of the simplest such compound, the methylidyne radical or unsubstituted carbyne H−C· or H−C3·, in which the functional group is a hydrogen atom.