The dioxygenyl

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

, , is a rarely-encountered oxycation in which both oxygen atoms have a formal

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...

of . It is formally derived from

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

by the removal of an

electron The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no ...

: :O₂ → + e⁻ The energy change for this process is called the ionization energy of the oxygen molecule. Relative to most molecules, this ionization energy is very high at 1175 kJ/mol. As a result, the scope of the chemistry of is quite limited, acting mainly as a 1-electron oxidiser.

Structure and molecular properties

has a bond order of 2.5, and a

bond length In molecular geometry, bond length or bond distance is defined as the average distance between nuclei of two bonded atoms in a molecule. It is a transferable property of a bond between atoms of fixed types, relatively independent of the rest of ...

of 112.3 pm in solid O₂ sF₆ It is

isoelectronic Isoelectronicity is a phenomenon observed when two or more molecules have the same structure (positions and connectivities among atoms) and the same electronic configurations, but differ by what specific elements are at certain locations in th ...

with nitric oxide and is paramagnetic. The

bond energy In chemistry, bond energy (''BE''), also called the mean bond enthalpy or average bond enthalpy is the measure of bond strength in a chemical bond. IUPAC defines bond energy as the average value of the gas-phase bond-dissociation energy (usually ...

is 625.1 kJ mol⁻¹ and the stretching frequency is 1858 cm⁻¹, both of which are high relative to most of the molecules.

Synthesis

Neil Bartlett demonstrated that

dioxygenyl hexafluoroplatinate Dioxygenyl hexafluoroplatinate is a compound with formula O2PtF6. It is a hexafluoroplatinate of the unusual dioxygenyl cation, O2+, and is the first known compound containing this cation. It can be produced by the reaction of dioxygen with platin ...

(O₂PtF₆), containing the dioxygenyl cation, can be prepared at room temperature by direct reaction of oxygen gas (O₂) with

platinum hexafluoride Platinum hexafluoride is the chemical compound with the formula Pt F6, and is one of seventeen known binary hexafluorides. It is a dark-red volatile solid that forms a red gas. The compound is a unique example of platinum in the +6 oxidation sta ...

(PtF₆): :O₂ + PtF₆ → The compound can also be prepared from a mixture of fluorine and oxygen gases in the presence of a

platinum Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish , a diminutive of "silver". Pla ...

sponge at 450 °C, and from

oxygen difluoride Oxygen difluoride is a chemical compound with the formula . As predicted by VSEPR theory, the molecule adopts a "bent" molecular geometry. It is strong oxidizer and has attracted attention in rocketry for this reason. With a boiling point of -144.7 ...

() above 400 °C: :6 + 2 Pt → 2 + At lower temperatures (around 350 °C),

platinum tetrafluoride Platinum tetrafluoride is the inorganic compound with the chemical formula . In the solid state, the compound features platinum(IV) in octahedral coordination geometry. Preparation The compound was first reported by Henri Moissan by the fluorin ...

is produced instead of dioxygenyl hexafluoroplatinate. Dioxygenyl hexafluoroplatinate played a pivotal role in the discovery of

noble gas compound In chemistry, noble gas compounds are chemical compounds that include an element from the noble gases, group 18 of the periodic table. Although the noble gases are generally unreactive elements, many such compounds have been observed, particularl ...

s. The observation that PtF₆ is a powerful enough oxidising agent to oxidise O₂ (which has a first

ionization potential Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule ...

of 12.2 eV) led Bartlett to reason that it should also be able to oxidise

xenon Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

(first ionization potential 12.13 eV). His subsequent investigation yielded the first compound of a

noble gas The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low ch ...

xenon hexafluoroplatinate Xenon hexafluoroplatinate is the product of the reaction of platinum hexafluoride with xenon, in an experiment that proved the chemical reactivity of the noble gases. This experiment was performed by Neil Bartlett at the University of British Co ...

. is also found in similar compounds of the form O₂MF₆, where M is

arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, ...

(As),

antimony Antimony is a chemical element with the symbol Sb (from la, stibium) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient t ...

(Sb),

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile me ...

(Au), niobium (Nb),

ruthenium Ruthenium is a chemical element with the symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most other chemical ...

(Ru),

rhenium Rhenium is a chemical element with the symbol Re and atomic number 75. It is a silvery-gray, heavy, third-row transition metal in group 7 of the periodic table. With an estimated average concentration of 1 part per billion (ppb), rhenium is one ...

(Re),

rhodium Rhodium is a chemical element with the symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring i ...

(Rh), vanadium (V), or

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...

(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 Dioxygen difluoride is a compound of fluorine and oxygen with the molecular formula O2F2. It can exist as an orange-colored solid which melts into a red liquid at . It is an extremely strong oxidant and decomposes into oxygen and fluorine even ...

with boron trifluoride or

phosphorus pentafluoride Phosphorus pentafluoride, P F5, is a phosphorus halide. It is a colourless, toxic gas that fumes in air. Preparation Phosphorus pentafluoride was first prepared in 1876 by the fluorination of phosphorus pentachloride using arsenic trifluoride, w ...

at −126 °C: :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 g(HF)sub>4(SbF₆)₉ can be made by ultraviolet irradiation of oxygen and fluorine dissolved in anhydrous hydrogen fluoride with a metal oxide. All attempts to prepare with chloro anions like met with failure.

Reactions

The reaction of O₂BF₄ with

at produces a white solid believed to be F–Xe–BF₂, containing an unusual xenon-boron bond: :2 O₂BF₄ + 2 Xe → 2 O₂ + F₂ + 2 FXeBF₂ The dioxygenyl salts O₂BF₄ and O₂AsF₆ react with

carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...

to give

oxalyl fluoride Oxalyl fluoride is the organofluorine compound with the formula (COF)2. It is a fluorinated derivative of oxalic acid. This colorless liquid is prepared by reaction of sodium fluoride with oxalyl chloride. Oxalyl fluoride is being investigated ...

, C₂O₂F₂, in high yield.

References

External links

*{{Commonscatinline, Dioxygenyl Oxycations Oxygen