89. Tipker, R. M.; Hughes, R. P.; Glueck, D. S.; Spinney, H. A.; Brammer, M. A.; Rheingold, A. L. Displacement of P-Stereogenic Phosphiranes from Rhodium by CO in Hydroformylation Catalysis. Organometallics 2024, 43, 427–431.
 

phosphirane_TOC  


Abstract

 

The P-stereogenic phosphiranes syn- and anti-Mes*PCH2CHPh (1-2, Mes* = 2,4,6-(t-Bu)3C6H2) formed precatalysts for hydroformylation of propylene using the precursor Rh(acac)(CO)2. Stoichiometric reactions gave the complexes Rh(acac)(L)(CO) (3-4). High-pressure NMR spectroscopy showed that Rh complex 3 was formed in the catalytic mixture, but on treatment with syngas (CO/H2), the phosphirane was displaced from rhodium. These observations were consistent with a density functional theory (DFT) study, which found that the equilibrium between Rh(acac)(CO)2, phosphiranes 1-2, CO, and Rh(acac)(L)(CO) (3-4) favored the starting materials. These results emphasized the competition between CO and phosphine ligands for coordination to rhodium during hydroformylation, and the importance of strong Rh-L coordination to ensure control of catalyst properties.


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