The effect of ligand substituents on spectroscopic and catalytic properties of water-compatible Cp*Ir-(pyridinylmethyl)sulfonamide-based transfer hydrogenation catalysts

Rosalind Booth, Adrian C. Whitwood, Anne-Kathrin Duhme-Klair*

*Corresponding author for this work

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Transition metal-based hydrogenation catalysts have applications ranging from high-value chemical synthesis to medicinal chemistry. A series of (pyridinylmethyl)sulfonamide ligands substituted with electron-withdrawing and -donating groups was synthesized to study the influence of the electronic contribution of the bidentate ligand in Cp*Ir piano-stool complexes. A variable temperature NMR investigation revealed a strong correlation between the electron-donating ability of the substituent and the rate of stereo-inversion of the complexes. This correlation was partially reflected in the catalytic activity of the corresponding catalysts. Complexes with electron-withdrawing substituents followed the trend observed in the variable temperature NMR study, thereby confirming the rate-determining step to be donation of the hydride ligand. Strongly electron-donating groups, on the other hand, caused a change in the rate-determining step to the formation of the iridium-hydride species. These results demonstrate that the activity of these catalysts can be tuned systematically via changes in the electronic contribution of the bidentate (pyridinylmethyl)sulfonamide ligands.
Original languageEnglish
Number of pages9
JournalInorganic Chemistry
Early online date11 Feb 2024
Publication statusE-pub ahead of print - 11 Feb 2024

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