Azobenzene dioxide is the organic compound with the formula (C6H5N(O))2. Both cis and trans isomers are known. The cis isomer has been crystallized. It is colorless.

Reactions

Structure of (PhNO)2 viewed down an approximate C2 axis. The N-O and N-N distances are 1.26 (average of two) and 1.33 Å, respectively. Color code: blue=N, red = O, gray = C.

When dissolved, azobenzene dioxide converts to deeply blue nitrosobenzene:

(C6H5N(O))2 → 2 C6H5NO

Azobenzene dioxide is a weak base, forming coordination complexes such as [Co[(C6H5N(O))2]4]2+.