- Phosphorus trifluoride
Name = Phosphorus trifluoride
ImageFile = Phosphorus-trifluoride-2D-dimensions.png
ImageName = Phosphorus trifluoride
ImageFile1 = Phosphorus-trifluoride-3D-vdW.png
ImageName1 = Phosphorus trifluoride
IUPACName = Phosphorus trifluoride
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
MeltingPt = −151.5 °C (121.7 K)
BoilingPt = −101.8 °C (171.4 K)
Section3 = Chembox Structure
MolShape = pyramidal
Dipole = 1.03 D
Section7 = Chembox Hazards
EUClass = not listed
FlashPt = non-flammable
Section8 = Chembox Related
Phosphorus trichloride Phosphorus tribromide Phosphorus triiodide
Nitrogen trifluoride Arsenic trifluoride
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 a ligandin metal complexes. As a ligand it parallels carbon monoxideJ. Chatt, "Nature" 165, 637-8 (1950).] in metal carbonyls, and indeed its toxicity is due to the fact that it binds with the ironin blood haemoglobin in a similar way to carbon monoxide.
Phosphorus trifluoride has a bond angle of 96.3°.
Gaseous 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).
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 anhydrous potassium hydroxidemay be used to dry it with little loss. With hot metals, phosphides and fluorides are formed. With Lewis bases such as ammoniaaddition products (adducts) are formed, and PF3 is oxidised by oxidising agents such as bromineor potassium 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
metals in low oxidation states. PF3 forms several complexes for which the corresponding CO derivatives (see metal 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 related metal carbonylcompound, with loss of CO. However, Nickel metalreacts 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 from dibenzenechromium:
:Cr(C6H6)2 + 6PF3 → Cr(PF3)6 + 2C6H6
Phosphorus trifluoride is usually prepared from
phosphorus trichloridevia halogen exchange using various fluorides, e.g. hydrogen fluoride, calcium fluoride, arsenic trifluoride, antimony trifluoride, or zinc 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
Phosphorus trifluoride is similar to
carbon monoxidein that it is a gas which strongly binds to ironin haemoglobin, preventing the blood from absorbing oxygen.
PF3 is highly toxic, comparable to
phosgene. [Greenwood, 1997]
* [http://www.npi.gov.au/database/substance-info/profiles/44.html National Pollutant Inventory - Flouride and compounds fact sheet]
* "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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