Phosphinidenes in chemistry

Chemistry

Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

 are chemical compounds containing a monovalent and diradical

Diradical

A diradical in organic chemistry is a molecular species with two electrons occupying two degenerate molecular orbitals . They are known by their higher reactivities and shorter lifetimes. In a broader definition diradicals are even-electron molecules that have one bond less than the number...

 phosphorus

Phosphorus

Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

 atom. They are the phosphorus analogs of carbene

Carbene

In chemistry, a carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons. The general formula is RR'C:, but the carbon can instead be double-bonded to one group. The term "carbene" may also merely refer to the compound H2C:, also called...

s and nitrene

Nitrene

In chemistry, a nitrene is the nitrogen analogue of a carbene. The nitrogen atom has only 6 valence electrons and is therefore considered an electrophile...

s. The parent compound is phosphinidene (HP) . This type of compound is very reactive and has only been observed in the gas phase and at cryogenic temperatures.

Terminal transition-metal-complexed phosphinidenes L_nM=P-R are phosphorus analogs of transition metal carbene complexes where L is a spectator ligand

Ligand

In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...

. Two isolable representatives of this group are [(OC)₅W=P-Ph] and Cp₂W=P-Mes*. In this type of compound the M=P bond is a true double bond

Double bond

A double bond in chemistry is a chemical bond between two chemical elements involving four bonding electrons instead of the usual two. The most common double bond, that between two carbon atoms, can be found in alkenes. Many types of double bonds between two different elements exist, for example in...

 with strength increasing going down a row in the transition metal group.

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

Bridging ligand

A bridging ligand is a ligand that connects two or more atoms, usually metal ions. The ligand may be atomic or polyatomic. Virtually all complex organic compounds can serve as bridging ligands, so the term is usually restricted to small ligands such as pseudohalides or to ligands that are...

. One example is the ter-butylphosphinidene complex (t-BuP)Fe₃(CO)₁₀. In clusters, phosphinidene is electronically similar to sulfide.