Heterogenized Molecular Rhodium Phosphine Catalyst within Metal-Organic Framework for Ethylene Hydroformylation

Molecularly-defined organometallic rhodium phosphine complexes were efficiently heterogenized within a MOF structure without affecting neither their molecular nature nor their catalytic behavior. Phosphine-functionalized MOF-808 served as solid ligand in a series of eight rhodium phosphine catalysts. These MOF-heterogenized molecular catalysts showed activity up to 2100 h-1 for ethylene hydroformylation towards pro-pionaldehyde as sole carbon-containing product. Combined experimental and computational methods applied to this unique MOF-based molecular system allowed unravelling structure and evolution of the Rh active species within the MOF under catalytic conditions, in line with molecular mechanisms at play during the hydroformylation reaction. The MOF-808 designed as a porous crystalline macroligand for well-defined molecular catalysts allows benefiting from molecular-scale understanding of interactions and mechanisms as well as from stabilization through site-isolation and recycling ability.