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

TY - JOUR

T1 - The effect of ligand substituents on spectroscopic and catalytic properties of water-compatible Cp*Ir-(pyridinylmethyl)sulfonamide-based transfer hydrogenation catalysts

AU - Booth, Rosalind

AU - Whitwood, Adrian C.

AU - Duhme-Klair, Anne-Kathrin

N1 - © 2024 The Authors.

PY - 2024/2/26

Y1 - 2024/2/26

N2 - 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.

AB - 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.

U2 - 10.1021/acs.inorgchem.3c04040

DO - 10.1021/acs.inorgchem.3c04040

M3 - Article

SN - 0020-1669

JO - Inorganic Chemistry

JF - Inorganic Chemistry

ER -