Synthesis of Methylated, Hydroxylated, and Aminated Metallaaromatics via Ring-Opening Reactions of the Fused Three-Membered Ring Units

The development of efficient functionalization methods for metallaaromatics is pivotal in manipulating their structural and chemical properties. While introducing hydroxyl and amino moieties into metallaaromatics is highly desirable, relevant reports remain scarce. In our approach, we exploit the reaction of hydroxylamine with a fused compound composed of a metallapentalene moiety and an unsaturated three-membered metallacycle. Upon exposure to air, hydroxylamine is oxidized by heating and forms a nitrosyl anion that replaces the chloride ligand within this system. The ligand exchange triggers the ring opening of the three-membered metallacycles, which is then followed by protonation, thereby generating a series of methylated, hydroxylated, and aminated metallaaromatic derivatives. This sequential process is accompanied by dearomatization and rearomatization within the metallapentalene frameworks, demonstrating the versatility of this new functionalization methodology.