Английская Википедия:Dioxygenyl
Шаблон:Other uses of Шаблон:Chembox The dioxygenyl ion, Шаблон:Chem, is a rarely-encountered oxycation in which both oxygen atoms have a formal oxidation state of Шаблон:Math. It is formally derived from oxygen by the removal of an electron:
- O2 → Шаблон:Chem + 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.[1] As a result, the scope of the chemistry of Шаблон:Chem is quite limited, acting mainly as a 1-electron oxidiser.[2]
Structure and molecular properties
Шаблон:Chem has a bond order of 2.5, and a bond length of 112.3 pm in solid O2[AsF6].[3] It is isoelectronic with nitric oxide and is paramagnetic.[4] The bond energy is 625.1 kJ mol−1 and the stretching frequency is 1858 cm−1,[5] both of which are high relative to most of the molecules.
Synthesis
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):[6]
- O2 + PtF6 → Шаблон:Chem
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 (Шаблон:Chem) above 400 °C:[6]
- 6 Шаблон:Chem + 2 Pt → 2 Шаблон:Chem + Шаблон:Chem
At lower temperatures (around 350 °C), platinum tetrafluoride is produced instead of dioxygenyl hexafluoroplatinate.[6] 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.[7]
Шаблон:Chem is also found in similar compounds of the form O2MF6, where M is arsenic (As), antimony (Sb),[8] gold (Au),[9] niobium (Nb), ruthenium (Ru), rhenium (Re), rhodium (Rh),[10] vanadium (V),[11] or phosphorus (P).[12] Other forms are also attested, including O2GeF5 and (O2)2SnF6.[11]
The tetrafluoroborate and hexafluorophosphate salts may be prepared by the reaction of dioxygen difluoride with boron trifluoride or phosphorus pentafluoride at −126 °C:[12]
- 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.[13]
All attempts to prepare Шаблон:Chem with chloro anions like Шаблон:Chem met with failure.
Reactions
The reaction of O2BF4 with xenon at Шаблон:Cvt produces a white solid believed to be F–Xe–BF2, containing an unusual xenon-boron bond:[14]
- 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.[15]
References
External links
- ↑ Michael Clugston; Rosalind Flemming (2000). Advanced Chemistry, Oxford University Press, Шаблон:ISBN, Шаблон:ISBN, p. 355.
- ↑ Шаблон:Cite book
- ↑ Шаблон:Greenwood&Earnshaw p. 616
- ↑ Шаблон:Cotton&Wilkinson6th
- ↑ Шаблон:Cite journal
- ↑ 6,0 6,1 6,2 Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite book
- ↑ Шаблон:Cite journal
- ↑ 11,0 11,1 Шаблон:Cite book
- ↑ 12,0 12,1 Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
