NOVEL REACTIONS OF 1,2-DISUBSTITUTED BENZENES COORDINATED TO COBALT(III) - NEIGHBORING-GROUP PARTICIPATION

The pentaamminecobalt(III) complex of 1, 2-dicyanobenzene reacts with a stoichiometric amount of base to give the coordinated carboxamido complex (NH3)5Co(2-carboxamidobenzonitrile)2+. The latter complex cyclizes in base to the pentaamminecobalt(III) complex of l-oxo-3-iminoisoindolin-2-yl. However, in acid solution the coordinated amide complex undergoes an intramolecular rearrangement to form the coordinated nitrile-free amide compound (NH3)5Co(2-cyanobenzamide)3+. This nitrile complex is rapidly hydrolyzed, the reaction involving intramolecular catalysis by the free amide group. The product of the hydrolysis reaction, (NH3)5Co(2-carboxamidobenzamide)2+, cyclizes in acidic solution to (NH3)5Co(l-oxo-3-iminoisoindoline)3+ where the metal is coordinated to the exocyclic nitrogen (3 position). The characterization of the above complexes is described, and mechanisms for their formation are considered. © 1979, American Chemical Society. All rights reserved.