Abbreviations NO(+) ChemSpider ID 76569 | ChEBI ID 29120 | |
 | ||
The nitrosonium ion is NO+, in which the nitrogen atom is bonded to an oxygen atom with a bond order of 3, and the overall diatomic species bears a positive charge. This ion is usually obtained as the following salts: NOClO4, NOSO4H (nitrosylsulfuric acid, more descriptively written ONSO3OH), and NOBF4. The ClO−
4 and BF−
4 salts are slightly soluble in CH3CN. NOBF4 can be purified by sublimation at 200–250 °C and 0.01 mmHg (1.3 Pa).
Contents
- Lewis dot structure of no nitrosonium ion
- Hydrolysis
- As a diazotizing agent
- As an oxidizing agent
- Nitrosylation of arenes
- As a source of nitrosyl complexes
- References
NO+ is isoelectronic with CO, CN− and N2. It arises via protonation of nitrous acid:
HONO + H+ ⇌ NO+ + H2OLewis dot structure of no nitrosonium ion
Hydrolysis
NO+ reacts readily with water to form nitrous acid:
For this reason, NOBF4 must be protected from water or even moist air. With base, the reaction generates nitrite:
As a diazotizing agent
NO+ reacts with aryl amines, ArNH2, to give diazonium salts, ArN+
2. The resulting diazonium group is easily displaced (unlike the amino group) by a variety of nucleophiles.
As an oxidizing agent
NO+, e.g. as NOBF4, is a strong oxidizing agent:
NOBF4 is a convenient oxidant because the byproduct NO is a gas, which can be swept from the reaction using a stream of N2. Upon contact with air, NO forms NO2, which can cause secondary reactions if it is not removed. NO2 is readily detectable by its characteristic orange color.
Nitrosylation of arenes
Electron-rich arenes are nitrosylated using NOBF4. One example involves anisole:
Nitrosonium, NO+, is sometimes confused with nitronium, NO+
2, 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. One must be careful that [NO]+ is transferred vs. electron transfer (see above).