Boron monofluoride or
fluoroborylene is a chemical compound with formula BF, one atom of
boron and one of
fluorine. It was discovered as an unstable gas and only in 2009 found to be a stable
ligand combining with
transition metals, in the same way as
carbon monoxide. It is a subhalide, containing fewer than the normal number of fluorine atoms, compared with
boron trifluoride. BF is
isoelectronic with carbon monoxide and
dinitrogen and each molecule has 14 electrons.