Influence of linkers on the Kuratowski-type secondary building unit in nickel single-site MOFs for ethylene oligomerization catalysis: a computational study

Abstract

Ni-Kuratowski-type MOFs were studied computationally for ethylene oligomerization and the catalytic performance of sterically different linkers was elucidated.

Theoretical Insight into the Effect of Fluorine‐Functionalized Metal‐Organic Framework Supported Palladium Single‐Site Catalyst in the Ethylene Dimerization Reaction

“…However, the chain walking process is thermodynamically unfavorable by 12.4 kcal/mol, while the ethylene coordination (RI D ) into the hydride species (AE2 D ) is thermodynamically favorable by −4.6 kcal/mol. These results indicate that the PβH D intermediate is unlikely to undergo chain walking (Ts‐cw); thus, the 1‐butene instead of 2‐butene formation is the most selective product for Pd‐CFA‐1 MOF catalyst keeping trend as its nickel derivative [16,22] . Therefore, the distribution of α‐olefins using Pd‐CFA‐1 MOF seems to be sensitive to the experimental conditions, such as; ethylene pressure and the temperature, wherein this study at room temperature, the dimerization reaction prevails instead of isomerization reaction.…”

“…The chirality of the inorganic building unit of the CFA‐1 MOF gives rise to exploring which will be the most suitable site for the Pd (II) ion exchange and the monomer‘s subsequent coordination, also knowing that there is no experimental evidence on the exact location for a metal ion exchange either for the ethylene uptake metal. Thus, according to a previous study of the CFA‐1 MOF structure‘s peripheral sites, their reactivity effects were analyzed for the ethylene uptake [22] . Two different local coordination environments were analyzed because, according to Volkmer's paper, [15] one is sterically more demanding (pore size of 3.4 Å) and is present only in one of the inorganic building unit‘s peripheral sites (Site A in Figure 1).…”

“…To investigate the ED reaction mechanism catalyzed by Pd‐CFA‐1 and their competitiveness with the isomerization reaction, free energy profiles were computed considering the coordination site A and based on Figure 2a were performed. The computed Gibbs free energy profile (Figure 2b) indicated the energy associated with the ethylene adsorption is −1.6 kcal/mol, which is thermodynamically favorable compared to the ethylene uptake Ni‐CFA‐1 MOF catalyst [22] . This is an interesting result about the palladium chemistry because it improves the monomer binding, where in terms of the ethylene C=C bond length, this bond lengthens to 1.42 Å contrast to the 1.38 Å associated with their nickel derivative.…”

“…Pd-CFA-1 MOF catalyst keeping trend as its nickel derivative. [16,22] Therefore, the distribution of α-olefins using Pd-CFA-1 MOF seems to be sensitive to the experimental conditions, such as; ethylene pressure and the temperature, wherein this study at room temperature, the dimerization reaction prevails instead of isomerization reaction. Similar trends are observed in Brookhart-type homogeneous catalysts, which, when these catalysts are substituted with bulky ligands at conditions such as high pressure and low temperature, the chain walking process is extremely unfavorable.…”

“…The computational protocol adopted here was successfully applied in a previous study, [22] . The inorganic building units of CFA-1 were taken as a cluster model from periodic geometries optimized at the PBEÀ D3 level.…”