In chemistry, a carbyne is a monovalent carbon radical species containing an electrically neutral univalent carbon atom with three non-bonded electrons.[1]
A carbyne can occur as a short-lived reactive intermediate. For instance, fluoromethylidyne (CF) can be detected in the gas phase by spectroscopy as an intermediate in the flash photolysis of CHFBr2.[2] The carbon atom was generally found to be an electronic doublet: the valence electrons are arranged as one radical (unpaired electron) and one electron pair, leaving a vacant atomic orbital, rather than being a tri-radical. The carbon atom is a complex hybridization, so the simple Hund's rule analysis of a simple atom containing 3 p orbitals (or 4 sp3 hybrids) is not correct.
Carbynes are incorporated in Transition metal carbyne complexes[3][4] as a trivalent ligand. For example, in [WBr(CO)2(2,2'-bipyridine)C-Aryl] and [WBr(CO)2(PPh3)2C-NR2]. An example of how to make such a compound would be to react [W(CO)6] with Lithium diisopropylamide to form [(iPr2N)(OLi)C=W(CO)5]. This is then reacted with either oxalyl bromide or triphenylphosphine dibromide followed by triphenyl phosphine. Another method is to treat a methoxy metal carbene with a lewis acid.[5]