A DFT study on MOFs with rhodium-coordinated organic phosphine linkers modified by functional groups for catalytic hydroformylation of 1-butene

Abstract

The organic ligands containing different heteroatoms (N/O/P) to coordinate Rh-active metals were found active for the hydroformylation of 1-butene, and P-containing ligands were superior in catalytic activity and n/i selectivity. In this work, a model of MOF Rh-PCM-18 containing phosphine ligands, similar to the conventional rhodium-phosphine homogeneous catalyst, was constructed, then the phosphine ligands were modified by inserting functional groups to change the electronic properties of the ligands, which might improve the catalytic performance. Five different models were obtained and their structures and electronic properties were calculated. The adsorption energies of the reactant species and the reaction paths on these models were investigated. The results suggested that the enhancement of the electron-donating ability of the phosphine ligand increased the adsorption of CO and H and promoted the oxidative addition of H2 at the metal site, but caused a higher activation energy barrier of the first step. On the other hand, appropriate reduction in the electron-donating ability of the phosphine ligand weakened the adsorption of CO and H and led to a decrease in the energy barrier of the first two steps, which improved the catalytic performance. This work explored the influence of the electronic properties of organic phosphine ligands on the coordinated active metal catalyst for 1-butene hydroformylation, which provided a reference for the selection and modification of ligands when using MOFs to design heterogeneous catalysts for hydroformylation.