The nitrosonium

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

is , in which the

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

atom is bonded to an

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

atom with a

bond order In chemistry, bond order, as introduced by Linus Pauling, is defined as the difference between the number of bonds and anti-bonds. The bond order itself is the number of electron pairs (covalent bonds) between two atoms. For example, in diat ...

of 3, and the overall diatomic species bears a positive charge. It can be viewed as

nitric oxide Nitric oxide (nitrogen oxide or nitrogen monoxide) is a colorless gas with the formula . It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its che ...

with one electron removed. This ion is usually obtained as the following salts: , (

nitrosylsulfuric acid Nitrosylsulfuric acid is the chemical compound with the formula . It is a colourless solid that is used industrially in the production of caprolactam, and was formerly part of the lead chamber process for producing sulfuric acid. The compound is ...

, more descriptively written ) and . The and salts are slightly soluble in

acetonitrile Acetonitrile, often abbreviated MeCN (methyl cyanide), is the chemical compound with the formula and structure . This colourless liquid is the simplest organic nitrile (hydrogen cyanide is a simpler nitrile, but the cyanide anion is not clas ...

. NOBF₄ can be purified by sublimation at 200–250 °C and . is

isoelectronic Isoelectronicity is a phenomenon observed when two or more molecules have the same structure (positions and connectivities among atoms) and the same electronic configurations, but differ by what specific elements are at certain locations in the ...

with CO, and . It arises via protonation of

nitrous acid Nitrous acid (molecular formula ) is a weak and monoprotic acid known only in Solution (chemistry), solution, in the gas phase and in the form of nitrite () salts. Nitrous acid is used to make diazonium salts from amines. The resulting diazoni ...

: :HONO + H⁺ NO⁺ + H₂O

Chemical properties

Hydrolysis

reacts readily with water to form

: : 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. General properti ...

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 An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or "Electron acceptor, accepts"/"receives" an electron from a (called the , , or ). In ot ...

: * vs. ferrocene/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). 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 Anisole, or methoxybenzene, is an organic compound with the formula CH3OC6H5. It is a colorless liquid with a smell reminiscent of anise seed, and in fact many of its derivatives are found in natural and artificial fragrances. The compound is ...

: : 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. One must be careful that Osup>+ is transferred vs. electron transfer (see above). : (C₆Et₆)Cr(CO)₃ + NOBF₄ → C₆Et₆)Cr(CO)₂(NO)F₄ + CO

References

{{Nitrogen compounds Oxycations Nitrogen(III) compounds