diphosphorus tetrafluoride
{{Chembox
| Name =
| ImageFileR2 = P2F4-mol-3d.png
| ImageFileL2 = Image:Phosphor(II)-fluorid.png
| IUPACName = difluorophosphanyl(difluoro)phosphane
| OtherNames = tetrafluorodiphosphine; phosphorus difluoride
| SystematicName =
| Section1 = {{Chembox Identifiers
| CASNo = 13824-74-3
| PubChem = 139615
| ChemSpiderID = 123129
| StdInChI=1S/F4P2/c1-5(2)6(3)4
| StdInChIKey = PCIAPVMJDQUHAP-UHFFFAOYSA-N
| SMILES = FP(F)P(F)F
}}
| Section2 = {{Chembox Properties
| Formula = {{chem2|P2F4}}
| MeltingPtC=−86.5
| BoilingPtC=−6.2
}}
| Section3 =
| Section4 =
| Section5 =
| Section6 =
| Section9 = {{Chembox Related
| OtherCations = dinitrogen tetrafluoride
diarsenic tetrafluoride
| OtherAnions = Diphosphorus tetrachloride
Diphosphorus tetrabromide
Diphosphorus tetraiodide
| OtherFunction_label = Binary Phosphorus halides
| OtherFunction = phosphorus trifluoride
phosphorus pentafluoride
| OtherCompounds = diphosphane
diphosphines
}}
}}
Diphosphorus tetrafluoride is a gaseous compound of phosphorus and fluorine with formula {{chem2|P2F4}}. Two fluorine atoms are connected to each phosphorus atom, and there is a bond between the two phosphorus atoms. Phosphorus can be considered to have oxidation state +2, as indicated by the name phosphorus difluoride.{{cite book |last1=Toy |first1=Arthur D. F. |title=The Chemistry of Phosphorus: Pergamon Texts in Inorganic Chemistry |date=2016 |publisher=Elsevier |isbn=978-1-4831-3959-3 |page=418 |url=https://books.google.com/books?id=sAJPDAAAQBAJ&pg=PA418 |language=en}}
Production
Diphosphorus tetrafluoride was discovered in 1966 by Max Lustig, John K. Ruff and Charles B. Colburn at the Redstone Research Laboratories. The initial synthesis reacted phosphorus iododifluoride with mercury at room temperature:{{cite journal |last1=Lustig |first1=Max |last2=Ruff |first2=John K. |last3=Colburn |first3=Charles B. |title=Diphosphorus Tetrafluoride and Diphosphorus Oxytetrafluoride |journal=Journal of the American Chemical Society |date=August 1966 |volume=88 |issue=16 |pages=3875 |doi=10.1021/ja00968a046|bibcode=1966JAChS..88.3875L }}
:{{chem2|2 PF2I + 2 Hg -> P2F4 + Hg2I2}}
Properties
The P−P bond in diphosphorus tetrafluoride is much stronger than the corresponding N−N bond in dinitrogen tetrafluoride which easily breaks into nitrogen difluoride. The infrared spectrum has absorption at 842 cm−1, 830 cm−1, 820 cm−1, and weaker at 408 cm−1 and 356 cm−1. The molecule has C2h symmetry.{{cite journal |last1=Rhee |first1=Kee H. |last2=Snider |first2=A.Monroe |last3=Miller |first3=Foil A. |title=Infrared and Raman spectra and structure of P2F4 |journal=Spectrochimica Acta Part A: Molecular Spectroscopy |date=June 1973 |volume=29 |issue=6 |pages=1029–1035 |doi=10.1016/0584-8539(73)80142-4|bibcode=1973AcSpA..29.1029R }}
Reactions
Under ultraviolet light diphosphorus tetrafluoride reacts with alkynes connected to trifluoromethyl groups to add difluorophosphino (-{{chem2|PF2}}) groups on each side of a double bond. Other kinds of alkynes produced polymers with this treatment.{{cite journal |last1=Morse |first1=J.G. |last2=Mielcarek |first2=J.J. |title=Photoreactions of tetrafluorodiphosphine with alkynes |journal=Journal of Fluorine Chemistry |date=July 1988 |volume=40 |issue=1 |pages=41–49 |doi=10.1016/S0022-1139(00)81060-X|bibcode=1988JFluC..40...41M }} With alkenes, similarly bis(difluorophosphino) is added across the double bond.{{cite journal |last1=Morse |first1=Joseph G. |last2=Morse |first2=Karen W. |author-link2=Karen W. Morse|title=Photoreactions of tetrafluorodiphosphine with nonsubstituted olefins and perfluoroolefins |journal=Inorganic Chemistry |date=March 1975 |volume=14 |issue=3 |pages=565–569 |doi=10.1021/ic50145a024}}
Diphosphorus tetrafluoride reacts with diborane to yield another gas {{chem2|P2F4*BH3}} which does not condense above −85°C. This decomposes to yet another gas {{chem2|PF3*BH3}} and a polymer with formula PF.{{cite journal |last1=Morse |first1=Karen W. |last2=Parry |first2=Robert W. |title=The Basic Properties of Tetrafluorodiphosphine. The Synthesis of Tetrafluorodiphosphine Borane |journal=Journal of the American Chemical Society |date=January 1967 |volume=89 |issue=1 |pages=172–173 |doi=10.1021/ja00977a049|bibcode=1967JAChS..89..172M }}
Diphosphorus tetrafluoride reacts with oxygen or water to yield diphosphorus tetrafluoride oxide, which has one oxygen atom inserted between the two phosphorus atoms:{{cite journal |last1=Rudolph |first1=R. W. |last2=Taylor |first2=R. C. |last3=Parry |first3=R. W. |title=Fluorophosphine Ligands. III. Syntheses Involving PF I. The Preparation and Characterization of μ-Oxo-bisdifluorophosphine, Cyanodifluorophosphine, and Tetrafluorodiphosphine |journal=Journal of the American Chemical Society |date=August 1966 |volume=88 |issue=16 |pages=3729–3734 |doi=10.1021/ja00968a010|pmid=5916370 |bibcode=1966JAChS..88.3729R }}
:{{chem2|2 P2F4 + H2O -> 2 PHF2 + F2POPF2 }}
The latter compound is a gas with boiling point around −18 °C.