Rare direct imidation of aromatic metallacycle by reaction of CpCo(dithiolene) complex with N-halosuccinimide

The aromatic CpCo(S₂C₂(R)(H))] (R = Ph, Me, 9-phenanthryl, H) complexes reacted with N-halosuccinimides (NXS; X = Cl, Br, I) in carbon tetrachloride at room temperature to undergo the N-succinimide substitution reaction on the dithiolene ring, but no halogenated dithiolene complex was obtained. The imidation products CpCo(S₂C₂(R)(N-sccinimide))] were yielded up to 64% where X = I and R = 9-phenanthryl. The reaction of CpCo(S₂C₂(Ph)(H))] with N-bromophthalimide (NBP) also gave the imidation product CpCo(S₂C₂(Ph)(N-phthalimide))]. This is the rare direct imidation reaction to an aromatic metallacycle by NXS. The reaction of CpCo(S₂C₂H₂)] (R = H) with NIS afforded the double imidation product. One by-product in this reaction was the dithiolene-dithiolene homo-coupling product CpCo(S₂C₂(R))]₂ (R = Ph, Me, 9-phenanthryl). The microwave-enhanced (MW) reactions were attempted in the carbon tetrachloride solution. Although the solution temperature increased up to only 43 °C by MW irradiation, the imidation reaction worked with short reaction time.