A Sustainable Heterogeneous Iron Catalyst Fe/SBA‐15 towards Direct Arylation of Unactivated C(sp3)−H and C(sp2)−H Bonds with Arenes

Iron grafted over mesoporous silica (8wt%Fe/SBA-15) is a sustainable, efficient heterogeneous iron catalyst for direct arylation of biphenyl methane C(sp(3))-H and benzene C(sp(2))-H bonds. The selective extraction deposition (SED) technique was adopted to graft iron easily over the mesoporous support SBA-15 by using LaFeO3 as an iron precursor. The synthesized catalyst has been characterized by EPR spectroscopy, diffuse reflectance UV/Vis spectroscopy, and temperature programmed reduction (TPR) analysis to understand the coordination environment and state of oxidic iron species grafted over the mesoporous SBA-15. TPR results confirm the presence of isolated, clustered, oligomeric oxidic iron species in the catalyst. The adopted SED technique is highly successful for grafting 8wt% iron into the mesopores of SBA-15 without forming iron oxide particles. Unlike homogeneous iron, the 8wt%Fe/SBA-15 catalyst does not need support from an electron-withdrawing group and additives to carry out arylation of benzene and could be successfully recycled five times.