In chemistry phosphinidenes (IUPAC: phosphanylidenes, or in older chemistry phosphinediyls) are the phosphorus analogs of carbenes and nitrenes, having the general structure RP:. The name originated from the parent compound, phosphinidene (HP). They can exist in either a singlet state or triplet state, with the triplet state being lower in energy. This type of compound is very reactive. In 2016, the first isolable singlet phosphinidene (DOI: 10.1016/j.chempr.2016.04.001) has been achieved by Guy Bertrand in University of California, San Diego.
Terminal transition-metal-complexed phosphinidenes LnM=P-R are phosphorus analogs of transition metal carbene complexes where L is a spectator ligand. Two examples of this group are [(OC)5W=P-Ph] and Cp2W=P-Mes*.
In clusters
More common than complexes of terminal phosphinidine ligands are cluster compounds wherein the phophinidene is a triply and less commonly doubly bridging ligand. One example is the ter-butylphosphinidene complex (t-BuP)Fe3(CO)10. In clusters, phosphinidene is electronically similar to sulfide.