Exploring activity differences between the hydroformylation catalysts: Insights from theory

• Computational studies have been done for rhodium hydroformylation with DFT.
• Mono-coordinate monodentate ligand modified catalysts are seen to be more active.
• The slowest step is always the alkene coordination followed by migratory insertion.
• The population of mono-coordinate monodentate catalysts governs the overall activity.
• π complex stability is influential for higher activity of the catalysts.

Hydroformylation catalysis is the most important homogeneous catalysis process of the current day. The current computational investigation aims to understand the nature of the hydroformylation process when monodentate ligands are employed. The complete catalytic cycle for different monodentate ligands bound to the rhodium center has been studied with full quantum chemical calculations, with density functional theory (DFT). To the best of our knowledge, this is the first systematic investigation of the relative free energy surfaces for mono-coordinate monodentate and bi-coordinated monodentate ligands in hydroformylation catalysis. The results indicate that the barriers are lower for the mono-coordinate monodentate species in comparison to the bi-coordinate monodentate, for all the ligand cases studied, indicating higher activity for the mono-coordinate monodentate active species.

The rate determining step (RDS) in the hydroformylation cycle has been found to be faster for mono-coordinated monodentate ligands in comparison to bi-coordinated monodentate ligands, for a range of different ligand cases that have been studied computationally with density functional theory (DFT). Furthermore, the free energy profile has been seen to have the same characteristics regardless of the nature of the ligand employed, for all the cases investigated.Figure optionsDownload as PowerPoint slide