Methanium

Methanium
	"True" methanium, the metastable transitional state [CH5]+
	Fluxional methanium, [CH3(H2)]+
Names
	IUPAC name Methanium
	Other names carbonium (discouraged due to multiple definitions)
Identifiers
3D model (JSmol)	true methanium: Interactive image; fluxional methanium: Interactive image;
PubChem CID	21881157;
	InChI true methanium: InChI=1S/CH5/h1H5/q+1 Key: PXOFOHGGCICFQD-UHFFFAOYSA-N; fluxional methanium: InChI=1S/CH5/c1-2/h2H,1H3/q+1 Key: AJLDAZFHECSILY-UHFFFAOYSA-N;
	SMILES true methanium: [C+H5]; fluxional methanium: [CH3+].[HH];
Properties
Chemical formula	CH+5
Molar mass	17.051 g·mol−1
Conjugate base	Methane
Structure
Molecular shape	trigonal bipyramidal
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

In chemistry, methanium is a complex positive ion with formula [C H₅]⁺ (metastable transitional form, a carbon atom covalently bonded to five hydrogen atoms) or [CH₃(H₂)]⁺ (fluxional form, namely a molecule with one carbon atom covalently bonded to three hydrogen atoms and one dihydrogen molecule), bearing a +1 electric charge. It is a superacid and one of the onium ions, indeed the simplest carbonium ion.

It is highly unstable and highly reactive even upon having a complete octet, thus granting its superacidic properties.

Methanium can be produced in the laboratory as a rarefied gas or as a dilute species in superacids. It was prepared for the first time in 1950 and published in 1952 by Victor Talrose and his assistant Anna Konstantinovna Lyubimova.^[2]^[3] It occurs as an intermediate species in chemical reactions.

The methanium ion is named after methane (CH₄), by analogy with the derivation of ammonium ion (NH+4) from ammonia (NH₃).

^ Chemistry, International Union of Pure and Applied (2009). "carbonium ion". IUPAC Compendium of Chemical Terminology. IUPAC. doi:10.1351/goldbook.C00839. ISBN 978-0-9678550-9-7. Retrieved 27 November 2018.
^ Cite error: The named reference Talrose was invoked but never defined (see the help page).
^ Nikolaev, Eugene (1998). "Victor Talrose: an appreciation". Journal of Mass Spectrometry. 33 (6): 499–501. Bibcode:1998JMSp...33..499N. doi:10.1002/(SICI)1096-9888(199806)33:6<499::AID-JMS684>3.0.CO;2-C. ISSN 1076-5174.

[1] Chemistry, International Union of Pure and Applied (2009). "carbonium ion". IUPAC Compendium of Chemical Terminology. IUPAC. doi:10.1351/goldbook.C00839. ISBN 978-0-9678550-9-7. Retrieved 27 November 2018.

[Talrose-2] Cite error: The named reference Talrose was invoked but never defined (see the help page).

[Nikolaev1998-3] Nikolaev, Eugene (1998). "Victor Talrose: an appreciation". Journal of Mass Spectrometry. 33 (6): 499–501. Bibcode:1998JMSp...33..499N. doi:10.1002/(SICI)1096-9888(199806)33:6<499::AID-JMS684>3.0.CO;2-C. ISSN 1076-5174.

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