Reaction of nitrobenzene and azobenzene with transition metal compounds in low oxidation state

The reaction of metallocycle cluster compounds M_x?1C₄H₈(M = Ti; V; Cr; Mo; W or Fe) with nitrobenzene yields aniline and azobenzene, while the reaction with azobenzene yields aniline only. By means of mass spctrometry ¹⁵N isotope fractionation in a region where a natural abundance of the nitrogen isotope occurs it was stated that aniline and azobenzene arise independently of each other, and the reaction follows the nitrene mechanism. On the other hand aniline from azobenzene is formed as a result of -NN- cleavage to the multimetallic cluster centre.