Visible-light capture activates a thermodynamically inert Co -CF bond for direct C-H trifluoromethylation of arenes and heteroarenes. New trifluoromethylcobalt(III) complexes supported by a redox-active [OCO] pincer ligand were prepared. Coordinating solvents, such as MeCN, afford green, quasi-octahedral [( OCO)Co (CF )(MeCN) ] (2), but in non-coordinating solvents the complex is red, square pyramidal [( OCO)Co (CF )(MeCN)] (3). Both are thermally stable, and 2 is stable in light. But exposure of 3 to low-energy light results in facile homolysis of the Co -CF bond, releasing CF radical, which is efficiently trapped by TEMPO or (hetero)arenes. The homolytic aromatic substitution reactions do not require a sacrificial or substrate-derived oxidant because the Co by-product of Co -CF homolysis produces H . The photophysical properties of 2 and 3 provide a rationale for the disparate light stability.

Uranium derivatives of a redox-active, dioxophenoxazine ligand, (DOPO(q))2UO2, (DOPO(sq))UI2(THF)2, (DOPO(cat))UI(THF)2, and Cp*U(DOPO(cat))(THF)2 (DOPO = 2,4,6,8-tetra-tert-butyl-1-oxo-1H-phenoxazin-9-olate), have been synthesized from U(VI) and U(III) starting materials. Full characterization of these species show uranium complexes bearing ligands in three different oxidation states. The electronic structures of these complexes have been explored using (1)H NMR and electronic absorption spectroscopies, and where possible, X-ray crystallography and SQUID magnetometry.

Visible-light capture activates at hermodynamically inert Co III À CF 3 bond for direct C À Ht rifluoromethylation of arenes and heteroarenes.New trifluoromethylcobalt(III) complexes supported by aredox-active [OCO] pincer ligand were prepared. Coordinating solvents,such as MeCN,affordgreen, quasi-octahedral [( S OCO)Co III (CF 3 )(MeCN) 2 ]( 2), but in non-coordinating solvents the complex is red, square pyramidal [( S OCO)Co III (CF 3 )(MeCN)] (3). Both are thermally stable,a nd 2 is stable in light. But exposure of 3 to lowenergy light results in facile homolysis of the Co III ÀCF 3 bond, releasing CCF 3 radical, whichisefficiently trapped by TEMPOC or (hetero)arenes.T he homolytic aromatic substitution reactions do not require as acrificial or substrate-derived oxidant because the Co II by-product of Co III À CF 3 homolysis produces H 2 .The photophysical properties of 2 and 3 provide arationale for the disparate light stability.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.