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Names | |
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IUPAC name Phosphanium iodide | |
Other names Iodine phosphide | |
Identifiers | |
3D model (JSmol) | |
ChemSpider | |
ECHA InfoCard | 100.031.978 |
EC Number |
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PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
PH 4I | |
Molar mass | 161.910 g/mol |
Boiling point | 62 °C (144 °F; 335 K) Sublimes [1] |
decomposes | |
Structure | |
Tetragonal (P4/nmm) | |
a = 6.34 Å, c = 4.62 Å | |
Lattice volume (V) | 185.7 Å3 |
Formula units (Z) | 2 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Phosphonium iodide is a chemical compound with the formula PH
4I. It is an example of a salt containing an unsubstituted phosphonium cation (PH+
4). Phosphonium iodide is commonly used as storage for phosphine [2] and as a reagent for substituting phosphorus into organic molecules. [3]
Phosphonium iodide is prepared by mixing diphosphorus tetraiodide (P2I4) with elemental phosphorus and water at 80 °C and allowing the salt to sublime. [4] [5]
Its crystal structure has the tetragonal space group P4/nmm, which is a distorted version of the NH4Cl crystal structure; the unit cell has approximate dimensions 634×634×462 pm. [6] The hydrogen bonding in the system causes the PH+
4 cations to orient such that the hydrogen atoms point toward the I−
anions. [7]
At 62 °C and atmospheric pressure, phosphonium iodide sublimates and dissociates reversibly into phosphine and hydrogen iodide (HI). [1] It oxidizes slowly in air to give iodine and phosphorus oxides; it is hygroscopic [4] and is hydrolyzed into phosphine and HI: [8]
Phosphine gas may be devolved from phosphonium iodide by mixing an aqueous solution with potassium hydroxide: [9]
It reacts with elemental iodine and bromine in a nonpolar solution to give phosphorus halides; for example:
Phosphonium iodide is a powerful substitution reagent in organic chemistry; for example, it can convert a pyrilium into a phosphinine via substitution. [3] In 1951, Glenn Halstead Brown found that PH4I reacts with acetyl chloride to produce an unknown phosphine derivative, possibly CH3C(=PH)PH2·HI. [4]