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

Abstract

The aromatic [CpCo(S 2C 2(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(S 2C 2(R)( N-sccinimide))] were yielded up to 64% where X = I and R = 9-phenanthryl. The reaction of [CpCo(S 2C 2(Ph)(H))] with N-bromophthalimide (NBP) also gave the imidation product [CpCo(S 2C 2(Ph)( N-phthalimide))]. This is the rare direct imidation reaction to an aromatic metallacycle by NXS. The reaction of [CpCo(S 2C 2H 2)] (R = H) with NIS afforded the double imidation product. One by-product in this reaction was the dithiolene–dithiolene homo-coupling product [CpCo(S 2C 2(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.