Accelerating the Photocatalytic Atom Transfer Radical Addition Reaction Induced by Bi₂O₃ with Amines Experiment and Computation

Metal oxide semiconductors are widely used in photocatalysis for the sustainable synthesis of fine chemicals and fuels. However, the mechanisms and the actual catalytically active species involved in these photocatalytic processes are not yet fully understood. Herein, we reveal that the addition of certain amines can effectively accelerate the photocatalytic atom transfer radical addition (ATRA) reaction by stabilizing a soluble Bi-species formed through a reaction between Bi₂O₃ and diethyl bromomalonate using either N, N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) as a solvent. Moreover, thermodynamic calculations revealed that N, N, N’, N’-tetramethylethylenediamine (TMEDA), and DMF yield the most stable complexes [(κ²-TMEDA)₂BiBr₃], ultimately accelerating the formation of the targeted ATRA product.