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Methenium

Names
Preferred IUPAC name Methylium
Other names Methyl cation; Carbanylium
Identifiers
CAS Number	14531-53-4
3D model (JSmol)	Interactive image
Beilstein Reference	1839325
ChEBI	CHEBI:29437
ChemSpider	559136
Gmelin Reference	48893
PubChem CID	644094
UNII	IM9JMM7N0Y
CompTox Dashboard (EPA)	DTXSID301319120
InChI InChI=1S/CH3/h1H3/q+1Key: JUHDUIDUEUEQND-UHFFFAOYSA-N
SMILES
Properties
Chemical formula	CH3
Molar mass	15.034 g·mol
Related compounds
Related isoelectronic	borane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Infobox references

In organic chemistry, methenium (also called methylium, carbenium, 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.

Structure

Experiments and calculations generally agree that the methenium ion is planar, with threefold symmetry. The carbon atom is a prototypical (and exact) example of sp hybridization.

Preparation and reactions

For mass spectrometry studies at low pressure, methenium can be obtained by ultraviolet photoionization of methyl radical, or by collisions of monatomic cations such as C
and Kr
with neutral methane. In such conditions, it will react with acetonitrile CH
₃CN to form the ion (CH
₃)
₂CN
.

Upon capture of a low-energy electron (less than 1 eV), it will spontaneously dissociate.

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.

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.

See also

• Ammonium
• Ethanium
• Methanium

References

1. International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. p. 1089. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.
2. "Ions, Free Radicals, and Radical-Ion", Nomenclature of Organic Compounds, Advances in Chemistry, vol. 126, AMERICAN CHEMICAL SOCIETY, June 1974, pp. 216–224, doi:10.1021/ba-1974-0126.ch028, ISBN 978-0841201910
3. ^ Golob, L.; Jonathan, N.; Morris, A.; Okuda, M.; Ross, K.J. (1972). "The first ionization potential of the methyl radical as determined by photoelectron spectroscopy". Journal of Electron Spectroscopy and Related Phenomena. 1 (5). Elsevier BV: 506–508. doi:10.1016/0368-2048(72)80022-7. ISSN 0368-2048.
4. Sharma, R. B.; Semo, N. M.; Koski, W. S. (1987). "Dynamics of the reactions of methylium, methylene radical cation, and methyliumylidene with acetylene". The Journal of Physical Chemistry. 91 (15). American Chemical Society (ACS): 4127–4131. doi:10.1021/j100299a037. ISSN 0022-3654.
5. McEwan, Murray J.; Denison, Arthur B.; Huntress, Wesley T.; Anicich, Vincent G.; Snodgrass, J.; Bowers, M. T. (1989). "Association reactions at low pressure. 2. The methylium/methyl cyanide system". The Journal of Physical Chemistry. 93 (10). American Chemical Society (ACS): 4064–4068. doi:10.1021/j100347a039. ISSN 0022-3654.
6. Bahati, E. M.; Fogle, M.; Vane, C. R.; Bannister, M. E.; Thomas, R. D.; Zhaunerchyk, V. (2009-05-11). "Electron-impact dissociation of CD
   ₃ and CH
   ₃ ions producing CD
   ₂, CH
   and C
   fragment ions". Physical Review A. 79 (5). American Physical Society (APS): 052703. doi:10.1103/physreva.79.052703. ISSN 1050-2947.
7. Hogeveen, H.; Lukas, J.; Roobeek, C. F. (1969). "Trapping of the methyl cation by carbon monoxide; formation of acetic acid from methane". Journal of the Chemical Society D: Chemical Communications (16): 920. doi:10.1039/c29690000920. ISSN 0577-6171.
8. Sauers, Elisha (27 June 2023). "Webb telescope just found something unprecedented in the Orion Nebula - Astronomers are excited about the detection of a special molecule in space". Mashable. Archived from the original on 27 June 2023. Retrieved 27 June 2023.
9. Berné, Olivier; et al. (26 June 2023). "Formation of the Methyl Cation by Photochemistry in a Protoplanetary Disk". Nature. 621 (7977): 56–59. arXiv:2401.03296. doi:10.1038/s41586-023-06307-x. hdl:1887/3716674. PMID 37364766. S2CID 259260435. Archived from the original on 27 June 2023. Retrieved 27 June 2023.

v t e Molecules detected in outer space
Molecules	Diatomic Aluminium monochloride Aluminium monofluoride Aluminium(II) oxide Argonium Carbon cation Carbon monophosphide Carbon monosulfide Carbon monoxide Cyano radical Diatomic carbon Fluoromethylidynium Helium hydride ion Hydrogen chloride Hydrogen fluoride Hydrogen (molecular) Hydroxyl radical Iron(II) oxide Magnesium monohydride Methylidyne radical Nitric oxide Nitrogen (molecular) Imidogen Sulfur mononitride Oxygen (molecular) Phosphorus monoxide Phosphorus mononitride Potassium chloride Silicon carbide Silicon monoxide Silicon monosulfide Sodium chloride Sodium iodide Sulfanyl Sulfur monoxide Titanium(II) oxide Triatomic Aluminium(I) hydroxide Aluminium isocyanide Amino radical Carbon dioxide Carbonyl sulfide CCP radical Chloronium Diazenylium Dicarbon monoxide Disilicon carbide Ethynyl radical Formyl radical Hydrogen cyanide (HCN) Hydrogen isocyanide (HNC) Hydrogen sulfide Hydroperoxyl Iron cyanide Isoformyl Magnesium cyanide Magnesium isocyanide Methylene N2H Nitrous oxide Nitroxyl Ozone Methylidynephosphane Potassium cyanide Trihydrogen cation Sodium cyanide Sodium hydroxide Silicon carbonitride c-Silicon dicarbide SiNC Sulfur dioxide Thioformyl Thioxoethenylidene Titanium dioxide Tricarbon Water Four atoms Acetylene Ammonia Isocyanic acid Cyanoethynyl Formaldehyde Fulminic acid HCCN Hydrogen peroxide Hydromagnesium isocyanide Isocyanic acid Isothiocyanic acid Ketenyl Methylene amidogen Methyl cation Methyl radical Propynylidyne Protonated carbon dioxide Protonated hydrogen cyanide Silicon tricarbide Thioformaldehyde Tricarbon monoxide Tricarbon monosulfide Thiocyanic acid Five atoms Ammonium ion Butadiynyl Carbodiimide Cyanamide Cyanoacetylene Cyanoformaldehyde Cyanomethyl Cyclopropenylidene Formic acid Isocyanoacetylene Ketene Methane Methoxy radical Methylenimine Propadienylidene Protonated formaldehyde Silane Silicon-carbide cluster Six atoms Acetonitrile Cyanobutadiynyl radical E-Cyanomethanimine Cyclopropenone Diacetylene Ethylene Formamide HC4N Ketenimine Methanethiol Methanol Methyl isocyanide Pentynylidyne Propynal Protonated cyanoacetylene Seven atoms Acetaldehyde Acrylonitrile Vinyl cyanide Cyanodiacetylene Ethylene oxide Glycolonitrile Hexatriynyl radical Propyne Methylamine Methyl isocyanate Vinyl alcohol Eight atoms Acetic acid Aminoacetonitrile Cyanoallene Ethanimine Glycolaldehyde Hexapentaenylidene Methylcyanoacetylene Methyl formate Acrolein Nine atoms Acetamide Cyanohexatriyne Dimethyl ether Ethanol Methyldiacetylene Octatetraynyl radical Propene Ethanethiol Propionitrile N-Methylformamide Ten atoms or more Acetone Benzene Benzonitrile Buckminsterfullerene (C60, C60, fullerene, buckyball) C70 fullerene Cyanodecapentayne Ethylene glycol Ethyl formate Methyl acetate Methyl-cyano-diacetylene Methyltriacetylene Propionaldehyde Butyronitrile Pyrimidine Heptatrienyl radical
Deuterated molecules	Ammonia Ammonium ion Formaldehyde Formyl radical Heavy water Hydrogen cyanide Hydrogen deuteride Hydrogen isocyanide Propyne N2D Trihydrogen cation
Unconfirmed	Anthracene Dihydroxyacetone Methoxyethane Glycine Graphene Hemolithin H2NCO Linear C5 Naphthalene cation Phosphine Pyrene Silylidyne
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