 | |
 | |
| Names | |
|---|---|
| IUPAC name N-Oxonitramide[1] | |
Other names
| |
| Identifiers | |
3D model (JSmol) | |
| ChEBI | |
| ChemSpider |
|
| ECHA InfoCard | 100.031.013 |
| EC Number |
|
| UNII | |
| UN number | 2421 |
| |
| |
| Properties | |
| N2O3 | |
| Molar mass | 76.011 g·mol−1 |
| Appearance | Deep blue liquid |
| Density |
|
| Melting point | −100.7[2] °C (−149.3 °F; 172.5 K) |
| Boiling point | 3.5 °C (38.3 °F; 276.6 K) (dissociates[2]) |
| reacts to formnitrous acid | |
| Solubility | soluble inether |
| −16.0·10−6 cm3/mol | |
| Structure | |
| planar,Cs | |
| 2.122 D | |
| Thermochemistry | |
| 65.3 J/(mol·K) | |
Std molar entropy(S⦵298) | 314.63 J/(mol·K) |
Std enthalpy of formation(ΔfH⦵298) | 91.20 kJ/mol |
| Hazards | |
| GHS labelling:[3] | |
   | |
| Danger | |
| H270,H310+H330,H314 | |
| P220,P244,P260,P262,P264,P270,P271,P280,P284,P301+P330+P331,P302+P350,P303+P361+P353,P304+P340,P305+P351+P338,P310,P320,P321,P322,P361,P363,P370+P376,P403,P403+P233,P405,P410+P403,P501 | |
| NFPA 704 (fire diamond) | |
| Flash point | Non-flammable |
| Related compounds | |
Related compounds | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Dinitrogen trioxide (also known asnitrous anhydride) is theinorganic compound with theformulaN2O3. It is anitrogen oxide. It forms upon mixing equal parts ofnitric oxide andnitrogen dioxide and cooling the mixture below −21°C (−6°F):[4]
Dinitrogen trioxide is only isolable at low temperatures (i.e., in the liquid and solidphases). In liquid and solid states, it has a deep blue color.[2] At higher temperatures the equilibrium favors the constituent gases, withKD = 193 kPa (25°C).[5][clarification needed]
This compound is sometimes called "nitrogen trioxide", but this name properly refers to another compound, the (uncharged)nitrate radical•NO3.
The majorisomer of dinitrogen trioxide molecule contains anN–N bond. One of the numerousresonant structures of the molecule of dinitrogen trioxide isO=N−NO2, which can be described as anitroso group−N=O attached to anitro group−NO2 by asingle bond between the twonitrogen atoms. Similar tonitronium nitrate, this molecule can also co-exist in equilibrium with an ionic gas called nitrosonium nitrite ([NO]+[NO2]–)[6]
Typically, N–N bonds are similar in length to that inhydrazine (145pm). Dinitrogen trioxide, however, has an unusually long N–N bond at 186 pm. Some othernitrogen oxides also possess long N–N bonds, includingdinitrogen tetroxide (175 pm). TheN2O3 molecule isplanar and exhibitsCs symmetry. The dimensions displayed on the picture below come frommicrowave spectroscopy oflow-temperature,gaseousN2O3:[4]
ON-NO2 is considered as the "anhydride" of the unstablenitrous acid (HNO2), and produces it when mixed withwater, although an alternative structure might be anticipated for the true anhydride of nitrous acid (i.e.,O=N−O−N=O). That isomer can be produced from the reaction of tetrabutylammonium nitrite andtriflic anhydride indichloromethane solution at −30°C.[7]
