Pd/Cu2O/CuO as Active Sites on the Cyclometalated Pd(II)/Cu(II) Nanosheet: Active Centre Formation, Synergistic and Catalytic Mechanism

A key to understand relationships between structure and activity is help for rational designing high active catalytic films. In this research, a new bi-cyclometallic ferrocene imine Pd(II)/Cu(II) catalytic monolayer supported on graphene oxide (GO@Fcl-Pd/Cu) was fabricated, which exhibited a higher activity (TOF=1.48x10(6) h(-1)) in Suzuki coupling reaction. Enhanced higher activity was related to the in situ formed Pd/ Cu2O (CuO) active centre on the surface during catalysis. Fe in ferrocene had the redox ability for making Pd-0 more stability, meaning that Fe3+ was electron withdraw or donor during catalytic process, which could tune the electronic properties of the Pd and Cu in one complex and improve their electronic transferring to boost the activity. CuO/Cu2O could make Pd-0 more negative and stability. Ensemble synergistic effect, including the metals, metal oxide, ligand and GO could be described as that the electron transferred from GO via ferrocene to Pd or via Cu(II) to Pd made more negative, improving the oxidative addition. Meanwhile, aryl boronic acid adsorbed on the vicinal Cu(II), Cu2O and CuO around Pd-0 synergetic reaction easily with the Pd intermediate to form next intermediate.