Computational Insight into the Ligand Effect on the Original Activity of Rh-Catalyzed Formaldehyde Hydroformylation

Abstract

This study performs a computational examination of the effect of the ligand nature on the Rh–L interaction and of the formaldehyde hydroformylation for substituted rhodium–carbonyl catalysts using a range of realistic mono- and bidentate ligands (CO, P­(OMe)3, PPh3, DMI, and DPPE). The energy decomposition analysis of the Rh–L bond suggests the bidentate ligand, DPPE, shows the strongest interaction with Rh. The π-accepting capacity of monodentate ligands follows the sequence CO > P­(OMe)3 > PPh3 > DMI. Analysis of the potential energy surface reveals the σ-donor ligands serve to increase the energy of the active anionic complex [Rh­(CO)3L]−. No clear correlation has been found between the CO insertion/hydrogenolysis energy barrier and electronic properties of ligands, while the H2 oxidative addition barrier increases with increasing the ligand’s electron donating capacity. The investigation on the effect of the ligand (PPh3) coordination number demonstrates that the three-coordinated catalyst exhibits the highest energy barrier, and the influence of ligand steric hindrance on the H2 oxidative addition can be ignorable.

Parameterization of Phosphine Ligands Modified Rh Complexes to Unravel Quantitative Structure‐Activity Relationship and Mechanistic Pathways in Hydroformylation

“…We attempt to explore the origin of the activity difference further from the perspective of hydroformylation reaction mechanism using theoretical calculation. Since both mono‐ and di‐substituted Rh‐complexes are active species [18] and there is no significant difference in the major species’ energies [19] , herein the monosubstituted Rh species (HRh(CO) 3 L) was employed as the standard. The ligands, PPh 3 (L1) and P( p PhCF 3 ) 3 (L4), were chosen as representatives based on the fact that the TOF of L1 is nearly twice that of L4 with similar selectivity (Table S1).…”

In Situ XAS Diagnostics of Reductive Hydroformylation Reaction in Segmented Flow Under Elevated Pressure and Temperature

“…The hydridocarbonyl complexes, which are active in hydroformylation, are formed in situ under the reaction conditions, while the initial Rh or Co complexes act only as precursors. Ligands play a key role in the properties of resulting active species, and thus, the development of improved catalysts requires a thorough understanding of the correlations between the ligand structure and the catalytic performance. − For a deeper understanding of the process, in situ methods are much more informative compared with the spectroscopic studies of the precursors or the starting solution.…”

Differential Evolution‐Based Optimization in Dimethyl Oxalate Hydrogenation

“…Furthermore, because of EG has a limited manufacturing capacity, it has a large market potential. From the market demand statistics 2, the global demand and consumption for EG will continue to grow in the upcoming decades. To meet this demand, the EG production process has been improvised in terms of reactants used, reaction kinetics, and mechanisms as well as catalyst selection by many researchers 3–7.…”