(661h) A Computational Mechanism Study of Ethylene Dimerization and Hydrogenation on Iridium Loaded Nu-1000 and Uio-66

Metal-organic frameworks (MOFs) are ordered, nanoporous materials built from metal-oxides and organic linkers. Due to their high porosity, surface area, chemical versatility and functionalization, they possess good potential for applications in catalysis, gas storage/separation, sensing etc. Recently, two synthetic methods, atomic layer deposition (ALD) and solvothermal deposition, have been used to load MOFs with metal complexes to enhance their catalytic potentials.

Zr-based MOFs have been a target for experimentalists since they are known to be stable under various experimental conditions which is mostly attributed to strong Zr-O bonding. In this computational study, mechanisms of ethylene dimerization and hydrogenation are investigated for Ir(C₂H₄)₂H₂ loaded NU-1000 and UiO-66 MOFs using density functional theory (DFT) employing M06-L functional. The cluster models of these two MOFs are obtained from their respective DFT optimized periodic unit cells by truncating organic linkers to acetate groups. To characterize the reaction mechanisms, activation barriers are compared for different mechanisms and they are contrasted with experimental selectivities. Moreover, CO stretching frequencies are computed for Ir(CO)₂ deposited structures to compare with experimental IR frequencies. Lastly, the interatomic distances in the structures are compared between optimized DFT models and EXAFS measurements.