Editing Phosphorus (section)

===Other inorganic compounds===
====Oxides and sulfides====
{{main|phosphorus oxides|phosphorus sulfides}}
[[File:Phosphorus-pentoxide-3D-balls.png|thumb|right|The tetrahedral structure of {{chem2|P4O10}} and {{chem2|P4S10}}]]
[[Phosphorus pentoxide]] ({{chem2|P4O10}}) is the [[acid anhydride]] of phosphoric acid, but several intermediates between the two are known. This waxy white solid reacts vigorously with water. Similarly, [[phosphorus trioxide]] ({{chem2|P4O6}}, also called tetraphosphorus hexoxide) is the anhydride of {{chem2|P(OH)3}}, the minor tautomer of phosphorous acid. The structure of {{chem2|P4O6}} is like that of {{chem2|P4O10}} without the terminal oxide groups. Mixed oxyhalides and oxyhydrides of phosphorus(III) are almost unknown. Meanwhile, phosphorus forms a wide range of sulfides, where the phosphorus can be in P(V), P(III) or other oxidation states. However, only two of them are commercially significant. [[Phosphorus pentasulfide]] ({{chem2|P4S10}}) has a structure analogous to {{chem2|P4O10}}, and is used in the manufacture of additives and pesticides.{{r|Heal1980}} The three-fold symmetric [[Phosphorus sesquisulfide]] ({{chem2|P4S3}}) is used in [[strike-anywhere match]]es.

====Halides====
{{main|phosphorus halides}}
Phosphorus [[halide]]s can have as oxidation state +3 in the case of trihalides and +5 for pentahalides and [[Chalcogen#With halogens|chalcoalide]]s, but also +2 for disphosphorus tetrahalides. All four symmetrical trihalides are well known: gaseous {{chem2|PF3|link=phosphorus trifluoride}}, the yellowish liquids {{chem2|PCl3|link=phosphorus trichloride}} and {{chem2|PBr3|link=phosphorus tribromide}}, and the solid {{chem2|PI3|link=phosphorus triiodide}}. These materials are moisture sensitive, hydrolysing to give [[phosphorous acid]]. The trichloride, a common reagent used for the manufacture of pesticides, is produced by chlorination of white phosphorus. The trifluoride is produced from the trichloride by halide exchange. {{chem2|PF3}} is toxic because it binds to [[haemoglobin]].

Most phosphorus pentahalides are common compounds. {{chem2|PF5|link=phosphorus pentafluoride}} is a colourless gas and the molecules have a [[trigonal bipyramid]]al geometry. With fluoride, it forms {{chem2|PF6-}}, an [[anion]] that is [[isoelectronic]] with {{chem2|SF6|link=sulfur hexafluoride}}. {{chem2|PCl5|link=phosphorus pentachloride}} is a colourless solid which has an ionic formulation of {{chem2|PCl4+PCl6-}}, but adopts a trigonal bipyramidal geometry when molten or in the vapour phase.{{r|Greenwood1997}} Both the pentafluoride and the pentachloride are [[Lewis acid]]s. Meanwhile, {{chem2|PBr5|link=phosphorus pentabromide}} is an unstable solid formulated as {{chem2|PBr4+Br-}}. {{chem2|PI5|link=phosphorus pentaiodide}} is not known.{{r|Greenwood1997}}

The most important phosphorus [[oxyhalide]] is [[phosphorus oxychloride]] ({{chem2|POCl3}}), which is approximately tetrahedral. It is prepared from {{chem2|PCl3}} and used in the manufacture of plasticizers. Phosphorus can also form thiohalides such as {{chem2|PSCl3|link=Thiophosphoryl chloride}}, and in rare cases selenohalides.

====Nitrides====
The PN molecule [[phosphorus mononitride]] is considered unstable, but is a product of crystalline [[triphosphorus pentanitride]] decomposition at {{convert|1100|K|C}}. Similarly, {{chem2|H2PN}} is considered unstable, and phosphorus nitride halogens like {{chem2|F2PN}}, {{chem2|Cl2PN}}, {{chem2|Br2PN}}, and {{chem2|I2PN}} oligomerise into cyclic [[polyphosphazene]]s. For example, compounds of the formula {{chem2|(PNCl2)_{''n''}|}} exist mainly as rings such as the [[trimer (chemistry)|trimer]] [[hexachlorophosphazene]]. The phosphazenes arise by treatment of phosphorus pentachloride with ammonium chloride:
:{{chem2|PCl5 + NH4Cl -> 1/''n'' (NPCl2)_{''n''} + 4 HCl}}
When the chloride groups are replaced by [[alkoxide]] ({{chem2|RO-}}), a family of polymers is produced with potentially useful properties.{{r|Mark1992}}

====Phosphides and phosphine====
{{main|Phosphide|Template:Phosphides}}
A wide variety of compounds which contain the containing the phosphide ion {{chem2|P(3−)}} exist, both with [[main-group element]]s and with [[metal]]s. They often exhibit complex structures, where phosphorus has the −3 oxidation state. Metal phosphides arise by reaction of metals with red phosphorus. The [[alkali metal]]s (group 1) and [[alkaline earth metal]]s (group 2) can also form compounds such as {{chem2|Na3P7|link=sodium phosphide}}. These compounds react with water to form [[phosphine]].{{r|Greenwood1997}} Some phosphide minerals are also known, like {{chem2|(Fe,Ni)2P|link=Allabogdanite}} and {{chem2|(Fe,Ni)3P|link=Schreibersite}}, but they are very rare on Earth, most instances occurring in [[Iron meteorite|iron-nickel meteorite]]s.

Phosphine ({{chem2|PH3}}) and its organic derivatives are structural analogues of [[ammonia]] ({{chem2|NH3}}), but the bond angles at phosphorus are closer to 90° for phosphine and its organic derivatives. It is an ill-smelling and toxic gas, produced by hydrolysis of [[calcium phosphide]] ({{chem2|Ca3P2}}). Unlike ammonia, phosphine is oxidised by air. Phosphine is also far less basic than ammonia. Other phosphines are known which contain chains of up to nine phosphorus atoms and have the formula {{chem2|P_{''n''}H_{''n''+2}|}}.{{r|Greenwood1997}} The highly flammable gas [[diphosphine]] ({{chem2|P2H4}}) is an analogue of [[hydrazine]].