Atomically Dispersed Iridium on MgO(111) Nanosheets Catalyze Benzene-Ethylene Coupling towards Styrene

Single atom catalysis has been recently recognized as an efficient utilization of metals in heterogeneous catalysis with the possibility to engender unusual reactivity. Yet, despite the observation of single atoms, controlling the uniformity in the coordination structures of supported species and understanding the structure-property relationships remains a grand challenge due to the surface structural complexity of the supports. Here, we combined the use of single-crystalline MgO(111) 2D nanosheets with surface organometallic chemistry to generate highly dispersed Ir(III) sites. The MgO(111) surfaces enable the formation of isolated Ir(III) single-sites stabilized by three 3-coordinated surface -O(H) anions at low loading (0.1 %_wt) as well as Ir pairs and trimers at higher loading (1 %_wt). These materials show unique catalytic properties and enable the coupling of benzene and ethylene into styrene, in contrast to the expected ethylbenzene, formed with the corresponding Ir-based homogeneous catalysts or with atomically dispersed Ir on MgO nanoparticles.