Coordination Sphere Control Enables Hydride-Free Tandem Electrocatalytic E-Selective Semi-Hydrogenation
Year: 2026
Type: preprint
Abstract: Hydride-free electrocatalytic semi-hydrogenation offers an alternative to metal-hydride-based platforms, yet controlling alkene stereochemistry through such pathways remains challenging. Herein, we report an E-selective, redox-mediated Co-catalyzed platform enabled by cooperative control of the catalyst coordination sphere via ligand denticity and acid identity. Using a triphosphine ligand and ammonium chloride acid reverses the stereochemical preference of a previously developed Z-selective system, providing access to a range of E-alkenes in high yields and excellent stereoselectivity (up to 92% yield and >20:1 E:Z). Experimental and computational mechanistic studies support a mechanism involving a distinct proton transfer step with a chloride-mediated organization of the ammonium proton donor and Co catalyst. This allows for an initial inner-sphere protonation prior to cobaltocene-mediated reduction of the resultant Co(III)-alkenyl intermediate, followed by subsequent outer-sphere protonation to yield trans alkenes. These findings illustrate that coordination-sphere organization and precise control of proton transfer pathways may serve as complementary design principles in stereoselective electrocatalysis.
Source: ChemRxiv
Institutions: Boston University, University of California System
Language: English
Subfield: Inorganic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223316357