dioxygenyl#Synthesis

{{chem|O|2|+}} has a bond order of 2.5, and a bond length of 112.3 pm in solid O₂[AsF₆].{{Greenwood&Earnshaw}} p. 616 It is isoelectronic with nitric oxide and is paramagnetic.{{Cotton&Wilkinson6th}} The bond energy is 625.1 kJ mol⁻¹ and the stretching frequency is 1858 cm⁻¹,{{cite journal | journal = J. Am. Chem. Soc. |author1=J. Shamir |author2=J. Binenboym |author3=H. H. Claassen | title = The vibrational frequency of the O₂⁺ cation | year = 1968 | volume = 90 | issue = 22 | pages = 6223–6224 | doi = 10.1021/ja01024a054 }} both of which are high relative to most of the molecules.

Neil Bartlett demonstrated that dioxygenyl hexafluoroplatinate (O₂PtF₆), containing the dioxygenyl cation, can be prepared at room temperature by direct reaction of oxygen gas (O₂) with platinum hexafluoride (PtF₆):

:O₂ + PtF₆ → {{chem|[O|2|]|+|[PtF|6|]|−}}

The compound can also be prepared from a mixture of fluorine and oxygen gases in the presence of a platinum sponge at 450 °C, and from oxygen difluoride ({{chem|O|F|2}}) above 400 °C:{{cite journal|title = Fluorides of the Noble Metals. Part II. Dioxygenyl hexafluoroplatinate(V), {{chem|[O|2|]|+|[PtF|6|]|-}}|first1 = Neil|last1 = Bartlett|authorlink1 = Neil Bartlett (chemist)|first2 = D. H.|last2 = Lohmann|year = 1962|volume = 115|journal = J. Chem. Soc.|pages = 5253–5261|doi = 10.1039/jr9620005253}}

:6 {{chem|OF|2}} + 2 Pt → 2 {{chem|[O|2|][Pt|F|6|]}} + {{chem|O|2}}

At lower temperatures (around 350 °C), platinum tetrafluoride is produced instead of dioxygenyl hexafluoroplatinate. Dioxygenyl hexafluoroplatinate played a pivotal role in the discovery of noble gas compounds. The observation that PtF₆ is a powerful enough oxidising agent to oxidise O₂ (which has a first ionization potential of 12.2 eV) led Bartlett to reason that it should also be able to oxidise xenon (first ionization potential 12.13 eV). His subsequent investigation yielded the first compound of a noble gas, xenon hexafluoroplatinate.{{cite journal|journal = Proc. Chem. Soc.|year = 1962|title = Xenon hexafluoroplatinate(V), {{chem|Xe|+|[PtF|6|]|-}}|pages = 197–236|first = Neil|last = Bartlett|authorlink = Neil Bartlett (chemist)|doi = 10.1039/PS9620000197}}

{{chem|O|2|+}} is also found in similar compounds of the form O₂MF₆, where M is arsenic (As), antimony (Sb),{{cite journal | journal = J. Am. Chem. Soc. | first1 = A. R. | last1 = Young | first2 = T. | last2 = Hirata | first3 = S. I. | last3 = Morrow | title = The Preparation of Dioxygenyl Salts from Dioxygen Difluoride | year = 1964 | volume = 86 | issue = 1 | pages = 20–22 | doi = 10.1021/ja01055a006 }} gold (Au),{{cite book

|first = Tsuyoshi

|last = Nakajima

|title = Fluorine-carbon and fluoride-carbon materials: chemistry, physics, and applications

|publisher = CRC Press

|year = 1995

|isbn = 0-8247-9286-6

}} niobium (Nb), ruthenium (Ru), rhenium (Re), rhodium (Rh),{{Cite journal| first1 = Michael J.| last1 = Vasile| first2 = Warren E.| last2 = Falconer| title = Vapour transport of dioxygenyl salts| journal = J. Chem. Soc., Dalton Trans.| volume = 1975| issue = 4| pages = 316–318| year = 1975| doi = 10.1039/DT9750000316}} vanadium (V),{{cite book

| first1 = Arnold F.

| last1 = Holleman

| first2 = Egon

| last2 = Wiberg

| title = Inorganic chemistry

| publisher = Academic Press

| year = 2001

| isbn = 0-12-352651-5

| page = 475

}} or phosphorus (P). Other forms are also attested, including O₂GeF₅ and (O₂)₂SnF₆.

The tetrafluoroborate and hexafluorophosphate salts may be prepared by the reaction of dioxygen difluoride with boron trifluoride or phosphorus pentafluoride at −126 °C:{{Cite journal| first1 = Irvine J.| last1 = Solomon| first2 = Robert I.|last2 = Brabets| first3 = Roy K.| last3 = Uenishi| first4 = James N.| last4 = Keith| first5 = John M.| last5 = McDonough| title = New Dioxygenyl Compounds| journal = Inorg. Chem.| volume = 3| issue = 3| page = 457| year = 1964| doi = 10.1021/ic50013a036}}

:2 O₂F₂ + 2 BF₃ → 2 O₂BF₄ + F₂

:2 O₂F₂ + 2 PF₅ → 2 O₂PF₆ + F₂

These compounds rapidly decompose at room temperature:

:2 O₂BF₄ → 2 O₂ + F₂ + 2 BF₃

:2 O₂PF₆ → 2 O₂ + F₂ + 2 PF₅

Some compounds including O₂Sn₂F₉, O₂Sn₂F₉·0.9HF, O₂GeF₅·HF, and O₂[Hg(HF)]₄(SbF₆)₉ can be made by ultraviolet irradiation of oxygen and fluorine dissolved in anhydrous hydrogen fluoride with a metal oxide.{{Cite journal|last1=Mazej|first1=Zoran|last2=Goreshnik|first2=Evgeny|date=2020-02-03|title=Syntheses of Dioxygenyl Salts by Photochemical Reactions in Liquid Anhydrous Hydrogen Fluoride: X-ray Crystal Structures of α- and β-O₂Sn₂F₉, O₂Sn₂F₉·0.9HF, O₂GeF₅·HF, and O₂[Hg(HF)]₄(SbF₆)₉|journal=Inorganic Chemistry|language=en|volume=59|issue=3|pages=2092–2103| pmid=31942804 | doi=10.1021/acs.inorgchem.9b03518|pmc=7307900|issn=0020-1669|doi-access=free}}

All attempts to prepare {{chem|O|2|+}} with chloro anions like {{chem|[O|2|]|+|[SbCl|6|]|−}} met with failure.

The reaction of O₂BF₄ with xenon at {{cvt|173|K|C}} produces a white solid believed to be F–Xe–BF₂, containing an unusual xenon-boron bond:{{Cite journal| first1 = C. T.| first2 = K. R.| title = Reaction of xenon with dioxygenyl tetrafluoroborate. Preparation of FXe-BF₂| last1 = Goetschel| journal = Journal of the American Chemical Society| volume = 94| issue = 9| pages = 3018–3021| year = 1972| doi = 10.1021/ja00764a022| last2 = Loos}}

:2 O₂BF₄ + 2 Xe → 2 O₂ + F₂ + 2 FXeBF₂

The dioxygenyl salts O₂BF₄ and O₂AsF₆ react with carbon monoxide to give oxalyl fluoride, C₂O₂F₂, in high yield.{{Cite journal| first1 = H.| last2 = Willner | first2 = H.| last3 = Eujen | first3 = R.| title = The reaction of dioxygenyl salts with {{su|p=13}}CO Formation of F{{su|p=13}}C(O){{su|p=13}}C(O)F| journal = Journal of Fluorine Chemistry| last1 = Pernice| volume = 112| issue = 2| pages = 277–590| year = 2001| doi = 10.1016/S0022-1139(01)00512-7}}

{{Reflist}}

• {{Commons category-inline|Dioxygenyl}}

Category:Oxycations

Category:Oxygen