Radical Pd(III)/Pd(I) reductive elimination in palladium sequences.
Résumé
Open-shell mechanisms are often at work in catalytic sequences involving first-row transition metals while usually not considered in palladium chemistry. Herein a computational study suggests their possible relevance in catalytic methods involving paramagnetic Pd(iii) intermediates. Indeed C-C bond forming reductive elimination previously thought to occur in Pd(iv) complexes has lower barriers in neutral, radical Pd(iii) intermediates instead. These species could form upon addition on Pd(ii) of an aryl radical generated via single electron transfer from a photo-active ruthenium complex and have the perfect stereoelectronic arrangement to smoothly undergo the coupling process.