Poly(2,2′-Bibenzimidazole)–Supported Iridium Complex: A Recyclable Metal–Polymer Ligand Bifunctional Catalyst for the <i>N</i>-Methylation of Amines with Methanol

Abstract

The design and development of new types of catalysts is one of the most important topics for modern chemistry. Herein, a polymer-supported iridium complex Cp*Ir@Poly(2,2'-BiBzIm) was designed and synthesized by the coordinative immobilization of [Cp*IrCl₂]₂ on 2,2'-bibenzimidazoles. In the presence of the catalyst (0.5 mol % Ir) and Cs₂CO₃ (0.3 equiv), a variety of <i>N</i>-methylated amines were obtained in high yields with complete selectivity. More importantly, the catalyst could be recycled without an obvious loss of activity for six cycles. Apparently, the designed catalyst combines the advantages of both homogeneous and heterogeneous catalysis.