nitrosonium

{{chem2|NO+}} is isoelectronic with CO, cyanide and dinitrogen. It arises via protonation of nitrous acid:

:HONO + H⁺ {{eqm}} NO⁺ + H₂O

In its infrared spectrum of its salts, ν_NO is a strong peak in the range 2150-2400 cm⁻¹.{{cite journal |doi=10.1039/JR9630003557 |title=670. The Infrared Spectrum of the Nitrosonium Ion |date=1963 |last1=Sharp |first1=D. W. A. |last2=Thorley |first2=J. |journal=Journal of the Chemical Society (Resumed) |page=3557 }}

{{See also|Nitrosation}}

{{chem2|NO+}} reacts readily with water to form nitrous acid:

:{{chem2|NO(+) + H2O → HONO + H(+)}}

For this reason, nitrosonium compounds must be protected from water or even moist air. With base, the reaction generates nitrite:

:{{chem2|NO(+) + 2 NaOH → NaNO2 + Na(+) + H2O}}

{{chem2|NO+}} reacts with aryl amines, {{chem2|ArNH2}}, to give diazonium salts, {{chem2|ArN2(+)}}. The resulting diazonium group is easily displaced (unlike the amino group) by a variety of nucleophiles.

File:Nitrosonium ion with amine reaction.png to form a diazonium salt]]

{{chem2|NO+}}, e.g. as {{chem2|NOBF4}}, is a strong oxidizing agent:{{cite journal | author = N. G. Connelly, W. E. Geiger | title = Chemical Redox Agents for Organometallic Chemistry | journal = Chem. Rev. | year = 1996 | volume = 96 | pages = 877–910 | doi = 10.1021/cr940053x | pmid=11848774 | issue = 2}}

• vs. ferrocene/ferrocenium, {{chem2|[NO]+}} in {{chem2|CH2Cl2}} solution has a redox potential of 1.00 V (or 1.46–1.48 V vs SCE),
• vs. ferrocene/ferrocenium, {{chem2|[NO]+}} in {{chem2|CH3CN}} solution has a redox potential of 0.87 V vs. (or 1.27–1.25 V vs SCE).

In organic chemistry, it selectively cleaves ethers and oximes, and couples diarylamines.{{cite book|title=Nitrosation|first=D. L. H.|last=Williams|publisher=Cambridge University|location=Cambridge, UK|year=1988|isbn=0-521-26796-X|url=https://archive.org/details/nitrosation0000will|url-access=registration|pages=21–22}}

{{chem2|NOBF4}} is a convenient oxidant because the byproduct NO is a gas, which can be swept from the reaction using a stream of {{chem2|N2}}. Upon contact with air, NO forms {{chem2|NO2}}, which can cause secondary reactions if it is not removed. {{chem2|NO2}} is readily detectable by its characteristic orange color.

Electron-rich arenes are nitrosylated using NOBF₄.{{cite journal|first1=E.|last1=Bosch|first2=J. K.|last2=Kochi|title=Direct Nitrosation of Aromatic Hydrocarbons and Ethers with the Electrophilic Nitrosonium Cation|journal=Journal of Organic Chemistry|year=1994|volume=59|issue=19 |pages=5573–5586|doi=10.1021/jo00098a015}} One example involves anisole:

: CH₃OC₆H₅ + NOBF₄ → CH₃OC₆H₄NO + HBF₄

Nitrosonium, {{chem2|NO+}}, is sometimes confused with nitronium, NO{{su|b=2|p=+}}, the active agent in nitrations. These species are quite different, however. Nitronium is a more potent electrophile than is nitrosonium, as anticipated by the fact that the former is derived from a strong acid (nitric acid) and the latter from a weak acid (nitrous acid).

{{main|Metal nitrosyl complex}}

NOBF₄ reacts with some metal carbonyl complexes to yield related metal nitrosyl complexes.T. W. Hayton, P. Legzdins, W. B. Sharp. "Coordination and Organometallic Chemistry of Metal-NO Complexes". Chemical Reviews 2002, volume 102, pp. 935–991. In some cases, [NO]⁺ does not bind the metal nucleophile but acts as an oxidant.

: (C₆Et₆)Cr(CO)₃ + NOBF₄ → [(C₆Et₆)Cr(CO)₂(NO)]BF₄ + CO

• Nitronium (NO₂⁺)
• Nitric oxide (NO)

{{Reflist}}

{{Nitric oxide signaling}}

{{Nitrogen compounds}}

Category:Oxycations

Category:Nitrogen(III) compounds