Photostable Ruthenium(II) Isocyanoborato Luminophores and Their Use in Energy Transfer and Photoredox Catalysis

Ruthenium(II) polypyridine complexes are among the most popular sensitizers in photocatalysis, but they face some severe limitations concerning accessible excited-state energies and photostability that could hamper future applications. In this study, borylation of heteroleptic ruthenium(II) cyanide with ?-diimine ancillary ligands is identified as a useful concept to elevate photoactive metal-to-ligand charge-transfer (MLCT) states obtain unusually photorobust compounds suitable for thermodynamically challenging energy transfer catalysis well oxidative reductive photoredox catalysis. B(C6F5)3 groups attached CN– stabilize metal-based t2g-like orbitals by ?0.8 eV, leading high 3MLCT (up 2.50 eV) more typical cyclometalated iridium(III) complexes. Through variation their ligands, nonradiative relaxation pathways involving higher-lying metal-centered can be controlled, luminescence quantum yields MLCT lifetimes optimized. These combined properties make respective isocyanoborato amenable photochemical reactions which common ruthenium(II)-based unsuited, due lack sufficient triplet or redox power. Specifically, includes photoisomerization reactions, sensitization nickel-catalyzed cross-couplings, pinacol couplings, decarboxylative C–C couplings. Our work relevant greater context tailoring coordination current challenges synthetic photochemistry solar conversion.