In chemistry, a phosphide is a compound containing the ion or its equivalent. Many different phosphides are known, with widely differing structures. Most commonly encountered on the binary phosphides, i.e. those materials consisting only of phosphorus and a less electronegative element. Numerous are polyphosphides, which are solids consisting of anionic chains or clusters of phosphorus. Phosphides are known with the majority of less electronegative elements with the exception of Hg, Pb, Sb, Bi, Te, and Po.Von Schnering, H.G. and Hönle , W. (1994) "Phosphides - Solid-state Chemistry" in ''Encyclopedia of Inorganic Chemistry''. R. Bruce King (ed.). John Wiley & Sons Finally, some phosphides are molecular.

Binary phosphides

Binary phosphides include phosphorus and one other element. An example of a group 1 phosphide is sodium phosphide (). Other notable examples include aluminium phosphide () and calcium phosphide (), which are used as pesticides, exploiting their tendency to release toxic

phosphine Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting ...

upon hydrolysis. Magnesium phosphide () also is moisture sensitive.

Indium phosphide Indium phosphide (InP) is a binary semiconductor composed of indium and phosphorus. It has a face-centered cubic ("zincblende (crystal structure), zincblende") crystal structure, identical to that of gallium arsenide, GaAs and most of the List of ...

() and gallium phosphide () are used as a semi-conductors, often in combination of related

arsenide In chemistry, an arsenide is a compound of arsenic with a less electronegative element or elements. Many metals form binary compounds containing arsenic, and these are called arsenides. They exist with many Stoichiometry, stoichiometries, and in t ...

s. Copper phosphide () illustrates a rare stoichiometry for a phosphide. These species are insoluble in all solvents - they are 3-dimensional solid state polymers. For those with electropositive metals, the materials hydrolyze: :

Polyphosphides

Polyphosphides contain bonds. The simplest polyphosphides would be derivatives of . The free anions are rarely encountered because they are so basic. Most members follow the octet rule. Well studied polyphosphides are derivatives of . The nomenclature for polyphosphides can be deceptive. As confirmed by

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

tin triphosphide and germanium triphosphide are not triphosphides, but hexaphosphides. They consist of ruffled ''cyclo''- subunits. Another example of deceptive nomenclature is "thorium pentaphosphide", which consists of a polymeric polyphosphide related to Hittorf's phosphorus. Several polyphosphides contain the cluster ions and polymeric chain anions (e.g. the helical ion) and complex sheet or 3-D anions. The range of structures is extensive.

Potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...

has nine phosphides: , , , , , , , , . Eight mono- and polyphosphides of

nickel Nickel is a chemical element; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive, but large pieces are slo ...

also exist: (, , , , , , , ). Two polyphosphide ions, found in and found in , are radical anions with an odd number of

valence electron In chemistry and physics, valence electrons are electrons in the outermost shell of an atom, and that can participate in the formation of a chemical bond if the outermost shell is not closed. In a single covalent bond, a shared pair forms with b ...

Preparation of phosphide and polyphosphide materials

There are many ways to prepare phosphide compounds. One common way involves heating a metal and

red phosphorus Red phosphorus is an Allotropes of phosphorus, allotrope of phosphorus. It is an amorphous polymeric red solid that is stable in air. It can be easily converted from white phosphorus under light or heating. It finds applications as matches and fir ...

(P) under inert atmospheric conditions or vacuum. In principle, all metal phosphides and polyphosphides can be synthesized from elemental phosphorus and the respective metal element in stoichiometric forms. However, the synthesis is complicated due to several problems. The

exothermic reaction In thermochemistry, an exothermic reaction is a "reaction for which the overall standard enthalpy change Δ''H''⚬ is negative." Exothermic reactions usually release heat. The term is often confused with exergonic reaction, which IUPAC define ...

s are often explosive due to local overheating. Oxidized metals, or even just an oxidized layer on the exterior of the metal, causes extreme and unacceptably high temperatures for beginning phosphorination. Hydrothermal reactions to generate nickel phosphides have produced pure and well crystallized nickel phosphide compounds, and . These compounds were synthesized through a solid-liquid reaction between and red phosphorus at 200 °C for 24 and 48 hours, respectively. Metal phosphides are also produced by reaction of tris(trimethylsilyl)phosphine with metal halides. In this method, the halide is liberated as the volatile trimethylsilyl chloride. MoP NR2 3

A method for the preparation of from red phosphorus and potassium ethoxide has been reported.

Molecular phosphides

Compounds with triple bonds between a metal and phosphorus are rare. The main examples have the formula , where R is a bulky organic substituent.

Organic phosphides

Many organophosphides are known. Common examples have the formula where R is an organic substituent and M is a metal. One example is lithium diphenylphosphide. The Zintl cluster is obtained with diverse alkali metal derivatives.

Natural examples

The mineral schreibersite is common in some meteorites.

References

{{Authority control Anions * Phosphorus(−III) compounds