A New Mechanism of Metal-Ligand Cooperative Catalysis in Transfer Hydrogenation of Ketones.

We report iridium catalysts IrCl(η-Cp*)(κ-(2-pyridyl)CHNSOCHX) (, X = CH and , X = F) for transfer hydrogenation of ketones with 2-propanol that operate by a previously unseen metal-ligand cooperative mechanism. Under the reaction conditions, complexes ( and ) derivatize to a series of catalytic intermediates: Ir(η-Cp*)(κ-(CHN)CHNSOAr) (), IrH(ηCp*)(κ-(2-pyridyl)CHNSOAr) (), and Ir(η-Cp*)(κ-(2-pyridyl)CHNSOAr) (). The structures of and were established by single-crystal X-ray diffraction.

Iridium-based hydride transfer catalysts: from hydrogen storage to fine chemicals.

Selective hydrogen transfer remains a central research focus in catalysis: hydrogenation and dehydrogenation have central roles, both historical and contemporary, in all aspects of fuel, agricultural, pharmaceutical, and fine chemical synthesis. Our lab has been involved in this area by designing homogeneous catalysts for dehydrogenation and hydrogen transfer that fill needs ranging from on-demand hydrogen storage to fine chemical synthesis. A keen eye toward mechanism has enabled us to develop systems with excellent selectivity and longevity and demonstrate these in a diversity of high-value applications.