In situspectroscopic investigations on BiPhePhos modified rhodium complexes in alkene hydroformylationElectronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4cy00481g

Structural and dynamic properties of BiPhePhos modified rhodium complexes under hydroformylation conditions have been investigated in detail by using high-pressure (HP) in situtransmission IR- and NMR-spectroscopy. An experiment design approach which combines component/reagent perturbations, in situ-FTIR measurements and chemometric peak group analysis (PGA) led to the identification of most relevant components. The ligand coordination in the structures of the hydrido and acyl 18-VE resting state complexes has been elucidated. The hydrido complex of the type e,e-[HRh(CO)2(P∩P)] represents the dominant resting state after catalyst preformation and during the n-regioselective hydroformylation. Dimer formation only takes place to a minor extent under severe reaction conditions under hydrogen depletion. Mono- and dinuclear hydrido monocarbonyl complexes are formed at higher ligand-to-metal ratios and low partial pressures of carbon monoxide. Both stereoisomeric forms of the bisphosphite modified acyl complexes e,a-[RC(O)Rh(CO)2(P∩P)] and e,e-[RC(O)Rh(CO)2(P∩P)] are generated as an equilibrium mixture.