The nitrosonium ion is , in which the

nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

atom is bonded to an

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

atom with a bond order of 3, and the overall diatomic species bears a positive charge. It can be viewed as nitric oxide with one electron removed. This ion is usually obtained as the following salts: , ( nitrosylsulfuric acid, more descriptively written ) and . The and salts are slightly soluble in acetonitrile . NOBF₄ can be purified by sublimation at 200–250 °C and .

Synthesis and spectroscopy

is isoelectronic with CO, and . It arises via protonation of nitrous acid: :HONO + H⁺ NO⁺ + H₂O In its infrared spectrum of its salts, ν_NO is a strong peak in the range 2150-2400 cm⁻¹.

Chemical properties

Hydrolysis

reacts readily with water to form nitrous acid: : For this reason, nitrosonium compounds must be protected from water or even moist air. With base, the reaction generates nitrite: :

As a diazotizing agent

reacts with aryl amines, , to give

diazonium salt Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. The parent, comp ...

s, . The resulting diazonium group is easily displaced (unlike the amino group) by a variety of nucleophiles. Nitrosonium ion with amine reaction

As an oxidizing agent

, e.g. as , is a strong oxidizing agent: * vs.

ferrocene Ferrocene is an organometallic chemistry, organometallic compound with the formula . The molecule is a Cyclopentadienyl complex, complex consisting of two Cyclopentadienyl anion, cyclopentadienyl rings sandwiching a central iron atom. It is an o ...

/ferrocenium, in solution has a redox potential of 1.00 V (or 1.46–1.48 V vs SCE), * vs. ferrocene/ferrocenium, in 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 di arylamines. is a convenient oxidant because the byproduct NO is a gas, which can be swept from the reaction using a stream of . Upon contact with air, NO forms , which can cause secondary reactions if it is not removed. is readily detectable by its characteristic orange color.

Nitrosylation of arenes

Electron-rich arenes are nitrosylated using NOBF₄. One example involves anisole: : CH₃OC₆H₅ + NOBF₄ → CH₃OC₆H₄NO + HBF₄ Nitrosonium, , is sometimes confused with nitronium, NO, 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).

As a source of nitrosyl complexes

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, Osup>+ does not bind the metal nucleophile but acts as an oxidant. : (C₆Et₆)Cr(CO)₃ + NOBF₄ → C₆Et₆)Cr(CO)₂(NO)F₄ + CO

References

{{Nitrogen compounds Oxycations Nitrogen(III) compounds