Two-Electron Photoreduction of Pd(II) Oxalates: In Crystallo Synthesis and Catalysis
Year: 2026
Type: preprint
Abstract: Discovery and optimization of cross-coupling catalysts require catalyst activation strategies that balance the operational simplicity of air-stable precatalysts with the need for air-sensitive, lowcoordinate and -valent intermediates for substrate activation and turnover. Here we introduce a general approach for on-demand catalyst activation via two-electron photoreduction of air-stable phosphine-ligated palladium(II) oxalates. The platform exploits rapid ligand exchange at (MeCN)2Pd(ox) to enable modular assembly of catalyst photoprecursors from a single precursor. In crystallo photochemistry and single-crystal Raman spectroscopy of phosphine-supported Pd oxalates establish that photoactivation proceeds via the extrusion of two molecules of CO2 and provide the Uirst crystallographic characterization of a Pd–CO2 adduct. Two-electron photoactivation translates to the solution phase to provide a platform to access Pd oxidative addition complexes (OACs) and to generate poison-free, on-cycle catalyst intermediates. The combination of rapid and quantitative ligand exchange coupled with facile two-electron photoreduction enables application in highthroughput experimentation (HTE) workUlows and on-plate ligand screening. Photogenerated catalysts are competitive with state-of-the-art precatalysts in both C–N cross-coupling and a newly developed base-free Suzuki reaction. These results establish Pd oxalates as general, photoactivated precursors to unsaturated catalyst intermediates that unlock streamlined, combinatorial workUlows for catalyst discovery and data-driven optimization.
Source: ChemRxiv
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7220848243