Oxycation
Positively charged polyatomic ion containing oxygen
From Wikipedia, the free encyclopedia
An oxycation, or oxocation, is an ion with the generic formula A
xOz+
y (where A represents a chemical element and O represents an oxygen atom). Their names normally end with the suffix "-ium" or "-yl".[1]
Isolable oxycations
A few salts of oxycations have been reported. They are all associated with lighter main group elements. The nitrogen-containing cations are NO+ and NO+
2. The latter is the active species in nitration reactions.
The Friedel-Crafts reaction is a classical organic reaction for attachment of acyl groups to arenes. The active acylating agent is often an acylium ion, several of which have been isolated..[2][3]
Oxycation nomenclature
Main group species
- NO+ - example: nitrosyl tetrafluoroborate
- NO+
2 - example: nitronium tetrafluoroborate - ClO+
2 - example: chloryl hexafluororuthenate[4]
More complicated oxycations include species like SOF3+.[5] Aluminyl, antimonyl, bismuthyl derivatives more closely resemble the situation for transition metal oxy cations in the sense that they are bonded to many Lewis bases. The cation [Bi6(O)4(OH)4]6+, a face-capped octahedral cluster, is one example.[6]
Transition metal species
Many transition compounds that contain an oxo ligand can be viewed as salts of a hypothetical "oxycation." In condensed phase, they are always complexed with strong Lewis bases.
- TiO2+ - example: titanyl sulfate, Ti(O)SO4(H2O).[7]
- VO3+ - example: vanadyl chloride, VOCl3
- VO2+ - example: vanadyl phosphate, VO(HPO4)
- CrO22+ - example: chromyl chloride, CrO2Cl2[8]
- MoO3+ - molybdenyl chloride, MoOCl3.[9]
- FeO2+ - examples include many ferryl intermediates
Actinide species
Oxycations in the gas-phase
While species like vanadyl (VO2+ and VO3+) do not exist in solution, some oxycations can be generated in the vacuum chamber of mass spectrometers. Using ion cyclotron resonance, these oxy cations have been shown to react even with simple hydrocarbons, attesting to the high reactivity.[12]