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Methenium
Ion of carbon with three hydrogens From Wikipedia, the free encyclopedia
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In organic chemistry, methenium (also called methylium, carbenium,[2] methyl cation, or protonated methylene) is a cation with the formula CH+
3. It can be viewed as a methylene radical (:CH
2) with an added proton (H+
), or as a methyl radical (•CH
3) with one electron removed. It is a carbocation and an enium ion, making it the simplest of the carbenium ions.[3]
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Structure
Experiments and calculations generally agree that the methenium ion is planar, with threefold symmetry.[3] The carbon atom is a prototypical (and exact) example of sp2 hybridization.
Preparation and reactions
For mass spectrometry studies at low pressure, methenium can be obtained by ultraviolet photoionization of methyl radical,[3] or by collisions of monatomic cations such as C+
and Kr+
with neutral methane.[4] In such conditions, it will react with acetonitrile CH
3CN to form the ion (CH
3)
2CN+
.[5]
Upon capture of a low-energy electron (less than 1 eV), it will spontaneously dissociate.[6]
It is seldom encountered as an intermediate in the condensed phase. It is proposed as a reactive intermediate that forms upon protonation or hydride abstraction of methane with FSO3H-SbF5. The methenium ion is very reactive, even towards alkanes.[7]
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Detection
Origins of life
In June 2023, astronomers detected, for the first time outside the Solar System, methyl cation, CH3+ (and/or carbon cation, C+), the known basic ingredients of life, in interstellar space.[8][9]
See also
References
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