Dinitrogen dioxide

{{Other use|hyponitrite}}

{{Chembox

|ImageFile=N2O2.svg

|Section1={{Chembox Identifiers

|index1_label = linear

|index2_label = cyclic

|index3_label = bicyclic

| PubChem1 = 6857661

| ChemSpiderID1 = 5256996

| ChemSpiderID2 = 29334740

| ChemSpiderID3 = 57448491

| ChEBI1 = 29797

| CASNo1_Ref = {{cascite|correct|CAS}}

| CASNo1 = 16824-89-8

| CASNo2 = 13354-65-9

| CASNo3 = 158362-70-0

| Gmelin = 1035

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = P6TX5AE4Q8

| StdInChI=1S/N2O2/c3-1-2-4

| StdInChIKey = AZLYZRGJCVQKKK-UHFFFAOYSA-N

| SMILES1 = N(=O)N=O

| SMILES2 = O1N=NO1

| SMILES3 = O1N2N1O2

}}

|Section2={{Chembox Properties

| N=2 | O=2

}}

}}

Dinitrogen dioxide is an inorganic compound having molecular formula {{chem|N|2|O|2}}. Many structural isomers are possible. The covalent bonding pattern O=N–N=O (a non-cyclic dimer of nitric oxide (NO)) is predicted to be the most stable isomer based on ab initio calculations and is the only one that has been experimentally produced.{{cite journal |last1=Nguyen |first1=Kiet A. |last2=Gordon |first2=Mark S. |last3=Montgomery |first3=John A. Jr. |last4=Michels |first4=H. Harvey |title=Structures, Bonding, and Energetics of N₂O₂ Isomers |journal=The Journal of Physical Chemistry |date=October 1994 |volume=98 |issue=40 |pages=10072–10078 |doi=10.1021/j100091a021|url=https://dr.lib.iastate.edu/bitstreams/be95a54e-5a0e-4578-9fb8-8853ba9bf311/download }} In the solid form, the molecules have C_2v symmetry: the entire structure is planar, with the two oxygen atoms cis across the N–N bond. The O–N distance is 1.15 Å, the N–N distance is 2.33 Å, and the O=N–N angle is 95°.{{cite journal |last1=Park |first1=Jong Keun |last2=Sun |first2=Hosung |title=Theoretical Determination of Geometrical Structures of the Nitric Oxide Dimer, (NO)₂ |journal=Bulletin of the Korean Chemical Society |date=1999 |volume=20 |issue=12 |pages=1399–1408 |url=http://www.koreascience.or.kr/article/JAKO199913464470127.page |language=ko |issn=0253-2964}}