Facile proton-coupled electron transfer enabled by coordination-induced E–H bond weakening to boron

We report the facile activation of aryl E–H (ArEH; E = N, O, S; Ar = Ph or C6F5) or ammonia N–H bonds via coordination-induced bond weakening to a redox-active boron center in the complex, (1−). Substantial decreases in E–H bond dissociation free energies (BDFEs) are observed upon substrate coordination, enabling subsequent facile proton-coupled electron transfer (PCET). A drop of >50 kcal mol−1 in H2N–H BDFE upon coordination was experimentally determined.