- Phosphorus trifluoride
Chembox new
Name = Phosphorus trifluoride
ImageFile = Phosphorus-trifluoride-2D-dimensions.png
ImageName = Phosphorus trifluoride
ImageFile1 = Phosphorus-trifluoride-3D-vdW.png
ImageName1 = Phosphorus trifluoride
IUPACName = Phosphorus trifluoride
Phosphorus(III) fluoride
Trifluorophosphane
Trifluorophosphorus
OtherNames = Trifluorophosphine
Section1 = Chembox Identifiers
CASNo = 7783-55-3
Section2 = Chembox Properties
Formula = PF3
MolarMass = 87.98 g/mol
Appearance = colorless gas
Density = 3.91 g/l, gas
Solubility =
slow hydrolysis
MeltingPt = −151.5 °C (121.7 K)
BoilingPt = −101.8 °C (171.4 K)
pKb =
Section3 = Chembox Structure
MolShape = pyramidal
Dipole = 1.03 D
Section7 = Chembox Hazards
ExternalMSDS =
EUClass = not listed
FlashPt = non-flammable
Section8 = Chembox Related
OtherAnions =Phosphorus trichloride Phosphorus tribromide Phosphorus triiodide
OtherCations =Nitrogen trifluoride Arsenic trifluoride
Function =ligand s
OtherFunctn =Carbon monoxide
OtherCpds =Phosphorus pentafluoride Phosphorus trifluoride (formula PF3, is a colourless and odourless
gas . It is highly toxic and it reacts slowly with water. Its main use is as aligand in metal complexes. As a ligand it parallelscarbon monoxide J. Chatt, "Nature" 165, 637-8 (1950).] inmetal carbonyl s, and indeed its toxicity is due to the fact that it binds with theiron in blood haemoglobin in a similar way to carbon monoxide.Physical properties
Phosphorus trifluoride has a bond angle of 96.3°.
Gas eous PF3 has a standard enthalpy of formation of -945 kJ/mol (-226 kcal/ mol). The phosphorus atom has an NMR chemical shift of 97 ppm (downfield of H3PO4).Properties
Phosphorus trifluoride hydrolyses especially at high pH, but it is less hydrolytically sensitive than
phosphorus trichloride . It does not attack glass except at high temperatures, and anhydrouspotassium hydroxide may be used to dry it with little loss. With hotmetal s, phosphides and fluorides are formed. WithLewis base s such asammonia addition products (adducts) are formed, and PF3 is oxidised by oxidising agents such asbromine orpotassium permanganate .As a ligand for transition metals, PF3 is a strong π-acceptor.N. N. Greenwood, A. Earnshaw, "Chemistry of the Elements", 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997, p 494] It forms a variety of metal complexes with
metal s in lowoxidation state s. PF3 forms several complexes for which the corresponding CO derivatives (seemetal carbonyl ) are unstable or nonexistent. Thus, Pd(PF3)4 is known, but Pd(CO)4 is not.D. Nicholls, "Complexes and First-Row Transition Elements", Macmillan Press, London, 1973.] Kruck, T.“Trifluorphosphin-Komplexe von Übergangsmetallen” Angewandte Chemie 1967, volume 79, p 27-43. DOI: 10.1002/ange.19670790104] [ Clark, R. J.; Busch, M. A. “Stereochemical studies of metal carbonylphosphorus trifluoride complexes” Accounts of Chemical Research, 1973, volume 6, pages 246-52.DOI: 10.1021/ar50067a005.] Such complexes are usually prepared directly from the relatedmetal carbonyl compound, with loss of CO. However,Nickel metal reacts directly with PF3 at 100 °C under 35 MPa pressure to form Ni(PF3)4, which is analogous to Ni(CO)4. Cr(PF3)6, the analogue of Cr(CO)6, may be prepared fromdibenzenechromium ::Cr(C6H6)2 + 6PF3 → Cr(PF3)6 + 2C6H6
Preparation
Phosphorus trifluoride is usually prepared from
phosphorus trichloride via halogen exchange using variousfluoride s, e.g.hydrogen fluoride ,calcium fluoride ,arsenic trifluoride ,antimony trifluoride , orzinc fluoride : [A. A. Williams, in "Inorganic Syntheses", Vol. V, 95-7 (1946).] ["Nouveau traité de chimie minérale : Tome X", Masson, Paris, France, 1956.] [cite journal | author = Ronald J. Clark, Helen Belefant, Stanley M. Williamson | title = Phosphorus Trifluoride | journal =Inorganic Syntheses | volume = 28 | pages = 310–315 | doi = 10.1002/9780470132593.ch77 | year = 1990]:2PCl3 + 3ZnF2 → 2PF3 + 3ZnCl2
Biological activity
Phosphorus trifluoride is similar to
carbon monoxide in that it is a gas which strongly binds toiron inhaemoglobin , preventing the blood from absorbing oxygen.Precautions
PF3 is highly toxic, comparable to
phosgene . [Greenwood, 1997]External links
* [http://www.npi.gov.au/database/substance-info/profiles/44.html National Pollutant Inventory - Flouride and compounds fact sheet]
References
* "Handbook of Chemistry and Physics", 71st edition, CRC Press, Ann Arbor, Michigan, 1990.
* J. March, "Advanced Organic Chemistry", 4th ed., p. 723, Wiley, New York, 1992.
* "The Merck Index", 7th edition, Merck & Co, Rahway, New Jersey, USA, 1960.
* A. D. F. Toy, "The Chemistry of Phosphorus", Pergamon Press, Oxford, UK, 1973.
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