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{{Short description|Ion of carbon with three hydrogens}}
[[File:Chemdg methenium 1pos.svg|thumb|200px|right|Methenium ({{chem|CH|3|+}}).]]
{{distinguish|methanium}}
⚫
In [[organic chemistry]], '''methenium''' (also called '''methylium''', '''methyl cation''' or '''protonated methylene''') is a [[cation|positive ion]] with formula {{chem|CH|3|+}}. It can be viewed as a [[methylene radical]] (''':'''{{chem|CH|2}}) with an added [[proton]] ({{chem|H|+}}), or as a [[methyl radical]] (•{{chem|CH|3}}) with one [[electron]] removed. It is one of the simplest [[carbocation]]s, indeed the simplest [[carbenium ion]], and an [[enium compound|enium ion]].<ref name=Golob/>
{{Chembox
<!-- Images -->
| ImageFile = Methyl_cation.svg
| ImageSize = 120px
<!-- Names -->
| PIN = Methylium<ref>{{cite book |author=[[International Union of Pure and Applied Chemistry]] |date=2014 |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 |publisher=[[Royal Society of Chemistry|The Royal Society of Chemistry]] |pages=1089 |doi=10.1039/9781849733069 |isbn=978-0-85404-182-4}}</ref>
| OtherNames = Methyl cation; Carbanylium
<!-- Sections -->
| Section1 = {{Chembox Identifiers
| CASNo = 14531-53-4
| CASNo_Ref = {{cascite|correct|CAS}}
| Beilstein = 1839325
| ChemSpiderID = 559136
| DTXSID = DTXSID301319120
| Gmelin = 48893
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = IM9JMM7N0Y
| PubChem = 644094
| SMILES = [CH3+]
| InChI = 1S/CH3/h1H3/q+1
| ChEBI = 29437
| InChIKey = JUHDUIDUEUEQND-UHFFFAOYSA-N
}}
| Section2 = {{Chembox Properties
| C = 1 | H = 3 | Formula_Charge = +
| Appearance =
| Density =
| MeltingPt =
| BoilingPt =
| Solubility =
}}
| Section3 = {{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt =
}}
| Section8 = {{Chembox Related
| OtherFunction = [[borane]]
| OtherFunction_label = [[isoelectronicity|isoelectronic]]
}}
}}


⚫
In [[organic chemistry]], '''methenium''' (also called '''methylium''', '''carbenium''',<ref>{{Citation|date=June 1974|pages=216–224|publisher=AMERICAN CHEMICAL SOCIETY|language=EN|doi=10.1021/ba-1974-0126.ch028|isbn=978-0841201910|title=Nomenclature of Organic Compounds|volume=126|series=Advances in Chemistry|chapter=Ions, Free Radicals, and Radical-Ion|chapter-url=https://archive.org/details/nomenclatureofor0000flet/page/216}}</ref> '''methyl cation''', or '''protonated methylene''') is a [[cation]] with the formula {{chem|CH|3|+}}. It can be viewed as a [[methylene radical]] (''':'''{{chem|CH|2}}) with an added [[proton]] ({{chem|H|+}}), or as a [[methyl radical]] (•{{chem|CH|3}}) with one [[electron]] removed. It is a [[carbocation]] and an [[enium ion]], making it the simplest of the [[carbenium ion]]s.<ref name=Golob/>
⚫
== Structure ==

The methenium ion is planar or nearly planar, with threefold symmetry.<ref name=Golob/>
⚫
==Structure==
Experiments and calculations generally agree that the methenium ion is planar, with threefold [[molecular symmetry|symmetry]].<ref name=Golob/> The carbon atom is a prototypical (and exact) example of sp<sup>2</sup> hybridization.


==Preparation and reactions==
==Preparation and reactions==
For [[mass spectrometry]] studies at low pressure, methenium can be obtained by [[ultraviolet]] [[photoionization]] of methyl radical,<ref name=Golob/> or by collisions of monoatomic cations like {{chem|C|+}} and {{chem|Kr|+}} with neutral methane.<ref name=Sharma/> In such conditions, it will react with [[methyl cyanide]] {{chem|CH|3|CN}} to form the ion {{chem|({{chem|CH|3}})|2|CN|+}}.<ref name=McEwan/>
For [[mass spectrometry]] studies at low pressure, methenium can be obtained by [[ultraviolet]] [[photoionization]] of methyl radical,<ref name=Golob/> or by collisions of monatomic cations such as {{chem|C|+}} and {{chem|Kr|+}} with neutral methane.<ref name=Sharma/> In such conditions, it will react with [[acetonitrile]] {{chem|CH|3|CN}} to form the ion {{chem|({{chem|CH|3}})|2|CN|+}}.<ref name=McEwan/>


The methenium ion is very reactive, even towards [[alkane]]s. Upon capture of a low-energy electron (less than 1 [[electron-volt|eV]]), it will spontaneously dissociate.<ref name=Bahati/>
Upon capture of a low-energy electron (less than {{val|1|ul=eV}}), it will spontaneously dissociate.<ref name=Bahati/>


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 [[Magic acid|FSO<sub>3</sub>H-SbF<sub>5</sub>]]. The methenium ion is very reactive, even towards [[alkane]]s.<ref>{{cite journal|last1=Hogeveen|first1=H.|last2=Lukas|first2=J.|last3=Roobeek|first3=C. F.|date=1969|title=Trapping of the methyl cation by carbon monoxide; formation of acetic acid from methane|journal=Journal of the Chemical Society D: Chemical Communications|language=en|issue=16|pages=920|doi=10.1039/c29690000920|issn=0577-6171}}</ref>
⚫
==References==
<references>


==Detection==
<ref name=Bahati>
{{main|List of interstellar and circumstellar molecules}}
E. M. Bahati, M. Fogle, C. R. Vane, M. E. Bannister, R. D. Thomas and V. Zhaunerchyk (2009),
===Origins of life===
"Electron-impact dissociation of {{chem|CD|3|+}} and {{chem|CH|3|+}} ions producing {{chem|CD|2|+}}, {{chem|CH|+}} and {{chem|C|+}} fragment ions". Physical Review A, volume 79, article 052703 {{doi|10.1103/PhysRevA.79.052703}}
{{main|Abiogenesis}}
</ref>
In June 2023, astronomers [[List of interstellar and circumstellar molecules|detected]], for the first time outside the Solar System, methyl cation, CH<sub>3</sub><sup>+</sup> (and/or [[carbon cation]], C<sup>+</sup>), the known basic ingredients of [[life]], in [[interstellar space]].<ref name="MSH-20230627">{{cite news |last=Sauers |first=Elisha |title=Webb telescope just found something unprecedented in the Orion Nebula - Astronomers are excited about the detection of a special molecule in space.|url=https://mashable.com/article/james-webb-space-telescope-orion-nebula |date=27 June 2023 |work=[[Mashable]] |url-status=live |archiveurl=https://archive.today/20230627153343/https://mashable.com/article/james-webb-space-telescope-orion-nebula |archivedate=27 June 2023 |accessdate=27 June 2023 }}</ref><ref name="NAT-20230626">{{cite journal |author=Berné, Olivier |display-authors=et al. |title=Formation of the Methyl Cation by Photochemistry in a Protoplanetary Disk |url=https://www.nature.com/articles/s41586-023-06307-x |date=26 June 2023 |journal=[[Nature (journal)|Nature]] |volume=621 |issue=7977 |pages=56–59 |doi=10.1038/s41586-023-06307-x |pmid=37364766 |s2cid=259260435 |url-status=live |archiveurl=https://archive.today/20230627160651/https://doi.org/10.1038/s41586-023-06307 |archivedate=27 June 2023 |accessdate=27 June 2023 |url-access=subscription |arxiv=2401.03296 |hdl=1887/3716674 }}</ref>


==See also==
<ref name=McEwan>
* [[Ammonium]]
Murray J. McEwan, Arthur B. Denison, Wesley T. Huntress Jr., Vincent G. Anicich, J. Snodgrass, M. T. Bowers (1989),
* [[Ethanium]]
"Association reactions at low pressure. 2. The methylium/methyl cyanide system". Journal of Physical Chemistry, volume 93, issue 10, pages 4064–4068. {{doi|10.1021/j100347a039}}
* [[Methanium]]
</ref>

<ref name=Sharma>
R. B. Sharma , N. M. Semo , W. S. Koski (1987),
"Dynamics of the reactions of methylium, methylene radical cation, and methyliumylidene with acetylene". Journal of Physical Chemistry, volume 91 issue 15, pages 4127–4131 {{doi|10.1021/j100299a037}}
</ref>

<ref name=Golob>
⚫
L. Golob, N. Jonathan, A. Morris, M. Okuda, K.J. Ross (1972), "The first ionization potential of the methyl radical as determined by photoelectron spectroscopy". Journal of Electron Spectroscopy and Related Phenomena, volume 1, issue 5, pages 506-508 {{doi|10.1016/0368-2048(72)80022-7}}
</ref>

</references>


⚫
==References==
{{Reflist|refs=
<ref name=Bahati>{{cite journal | last1=Bahati | first1=E. M. | last2=Fogle | first2=M. | last3=Vane | first3=C. R. | last4=Bannister | first4=M. E. | last5=Thomas | first5=R. D. | last6=Zhaunerchyk | first6=V. | title=Electron-impact dissociation of {{chem|CD|3|+}} and {{chem|CH|3|+}} ions producing {{chem|CD|2|+}}, {{chem|CH|+}} and {{chem|C|+}} fragment ions | journal=Physical Review A | publisher=American Physical Society (APS) | volume=79 | issue=5 | date=2009-05-11 | issn=1050-2947 | doi=10.1103/physreva.79.052703 | page=052703}}</ref>
<ref name=McEwan>{{cite journal | last1=McEwan | first1=Murray J. | last2=Denison | first2=Arthur B. | last3=Huntress | first3=Wesley T. | last4=Anicich | first4=Vincent G. | last5=Snodgrass | first5=J. | last6=Bowers | first6=M. T. | title=Association reactions at low pressure. 2. The methylium/methyl cyanide system | journal=The Journal of Physical Chemistry | publisher=American Chemical Society (ACS) | volume=93 | issue=10 | year=1989 | issn=0022-3654 | doi=10.1021/j100347a039 | pages=4064–4068}}</ref>
<ref name=Sharma>{{cite journal | last1=Sharma | first1=R. B. | last2=Semo | first2=N. M. | last3=Koski | first3=W. S. | title=Dynamics of the reactions of methylium, methylene radical cation, and methyliumylidene with acetylene | journal=The Journal of Physical Chemistry | publisher=American Chemical Society (ACS) | volume=91 | issue=15 | year=1987 | issn=0022-3654 | doi=10.1021/j100299a037 | pages=4127–4131}}</ref>
⚫
<ref name=Golob>{{cite journal | last1=Golob | first1=L. | last2=Jonathan | first2=N. | last3=Morris | first3=A. | last4=Okuda | first4=M. | last5=Ross | first5=K.J. | title=The first ionization potential of the methyl radical as determined by photoelectron spectroscopy | journal=Journal of Electron Spectroscopy and Related Phenomena | publisher=Elsevier BV | volume=1 | issue=5 | year=1972 | issn=0368-2048 | doi=10.1016/0368-2048(72)80022-7 | pages=506–508}}</ref>
}}
{{Molecules detected in outer space}}
[[Category:Carbocations]]
[[Category:Carbocations]]
[[Category:Ions]]
[[Category:Ions]]

Latest revision as of 17:42, 26 April 2024

Not to be confused with methanium.
Methenium
Names
Preferred IUPAC name
Methylium[1]
Other names
Methyl cation; Carbanylium
Identifiers
3D model (JSmol)
1839325
ChEBI
ChemSpider
48893
UNII
  • InChI=1S/CH3/h1H3/q+1
    Key: JUHDUIDUEUEQND-UHFFFAOYSA-N
  • [CH3+]
Properties
CH3+
Molar mass 15.034 g·mol−1
Related compounds
borane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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]

Structure[edit]

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[edit]

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]

Detection[edit]

Main article: List of interstellar and circumstellar molecules

Origins of life[edit]

Main article: Abiogenesis

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[edit]

References[edit]

  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. ^ a b c 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.
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