nitrosobenzene

Nitrosobenzene is the organic compound with the formula C6H5NO. It is one of the prototypical organic nitroso compounds. Characteristic of its functional group, it is a dark green species that exists in equilibrium with its pale yellow dimer. Both monomer and dimer are diamagnetic.

==Monomer-dimer equilibrium== Nitrosobenzene and other nitrosoarenes typically participate in a monomer-dimer equilibrium. The dimers are often favored in the solid state, whereas the deeply colored monomers are favored in dilute solution or at higher temperatures. The dimers can be formulated as Ar(O−)N+=N+(O−)Ar. They exist as cis- and trans-isomers due to the presence of the N–N double bond. The dimers are sometimes called azobenzenedioxides. The cis-trans isomerization occurs via the intermediacy of the monomer.