Nitrogen-containing diiron-hexacarbonyl complexes from 3-phenyl-2H-azirines
Reaction of 2,2-dimethyl-3-phenyl-2H-azirine (1) with diiron-enneacarbonyl yields as an insertion product, and in addition to other products, the diiron-hexacarbonyl complex 2 (Scheme 1), whose structure was derived from spectral data, in particular I3C-NMR.-data (Table 1). With trimethylamine oxide in benzene, 2 is converted into the urea derivative 3, and yields with cerium(IV)ammonium nitrate the nitrate 4 (Scheme 1). The analogous complexes 6 and 9 have been obtained by irradiation of 1-phenyl-vinyl azide (5) and ironpentacarbonyl (Scheme 1) and from vinyl isocyanate (8) and diiron-enneacarbonyl at 40° (Scheme 2), respectively.
The azirine 1, an acetylenic compound and diiron-enneacarbonyl in benzene react to give complexes of type 10 as the main product (Scheme 3). The structure of complex 10 has been established by X-ray single crystals analysis. On the 13C-NMR. time scale the carbonyl groups of compound 10 show a fluxional behaviour: below -50° the CO-groups of one of the two Fe (CO)3-groups undergo intranuclear exchange, above -50° the CO-groups of both Fe(CO)3-groups undergo internuclear exchange.
Tentative reaction mechanisms for the formation of the complexes of type 2 and 10 are formulated in Schemes 5, 6 and 7.