The mechanism of a self-assembled Pd(ferrocenylimine)–Si compound-catalysed Suzuki coupling reaction

Abstract

The Suzuki coupling reaction catalysed by a self-assembled monolayer of palladium(II)–ferrocenylimine complex supported on a silica surface (Pd(FcL)–Si) was studied in detail. The precatalyst hybrid was used for the in situ reduction of the catalytically active Pd⁰ to investigate the catalysis reaction using the water-drop contact angle method, atomic force microscopy, Raman spectroscopy, cyclic voltammetry and X-ray photoelectron spectroscopy. The first reaction step on the substrate, i.e., the oxidative addition of aryl halide to Pd⁰(FcL)–Si, was established. In addition, evidence of catalyst restoration to its initial state after catalytic reaction was obtained. These results suggested that surface sites on Pd(FcL)–Si were crucial to the catalysis of the coupling reaction. A Pd⁰/Pd^II redox interplay on the surface was also clearly detected. We believe that this catalytic reaction process can overcome the issues of low catalytic activity and reusability to provide a highly active and reusable heterogeneous catalytic system.