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1. Ligand‐to‐Metal Charge Transfer of Ag(II) CF ₂ X Carboxylates: Quantum Yield and Electrophotocatalytic Arene Fluoroalkylation Tuned by X

   https://doi.org/10.1002/anie.202511642  

   Campbell, Brandon M; Gordon, Jesse B; Raguram, Elaine Reichert; Reynolds, Kristopher G; Sullivan, Meghan G; Nocera, Daniel G (September 2025, Angewandte Chemie International Edition)

   Abstract Incorporation of CF₂X groups beyond CF₃into arene scaffolds is underdeveloped despite these groups’ utility as halogen‐bond donors and as precursors to bioisosteres. Herein, we report the synthesis, characterization, and comparative photochemistry of a suite of [Ag(II)(bpy)₂O₂CCF₂X]⁺and Ag(II)(bpy)(O₂CCF₂X)₂(bpy = 2,2´‐bipyridine, X = F, CF₃, Cl, Br, H, CH₃) carboxylate complexes. We find a dramatic effect of the X substituent on the efficiency of generating CF₂X radicals by ligand‐to‐metal charge transfer (LMCT), with Ag(II) photoreduction rates varying by over an order of magnitude and quantum yields spanning over 20%. We provide insight into how electronic and structural perturbations of the Ag(II)–O₂CCF₂X core are manifested in the LMCT quantum efficiency. With this information in hand, Ag(II)‐mediated electrophotocatalytic CF₂X functionalization is carried out on a range of (hetero)arenes. This work expands the nascent field of Ag(II)‐based photocatalysis by allowing for (hetero)aryl–CF₂X functionalization directly from unactivated fluoroalkyl carboxylate precursors. 

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2. The Role of Electron Transfer in Copper‐Mediated C(sp ² )−H Trifluoromethylation

   https://doi.org/10.1002/anie.202420677  

   Ball, Margaret_A P; Myers, Preston J; Ritch, Grayson D; Bower, Jamey K; Moore, Curtis E; Szymczak, Nathaniel K; Zhang, Shiyu (February 2025, Angewandte Chemie International Edition)

   Abstract We report copper(II) and copper(III) trifluoromethyl complexes supported by a pyridinedicarboxamide ligand (L) as a platform for investigating the role of electron transfer in C(sp²)−H trifluoromethylation. While the copper(II) trifluoromethyl complex is unreactive towards (hetero)arenes, the formal copper(III) trifluoromethyl complex performs C(sp²)−H trifluoromethylation of a wide range of (hetero)arenes. Mechanistic studies using the copper(III) trifluoromethyl complex suggest that the mechanism of arene trifluoromethylation is substrate‐dependent. When the thermodynamic driving force for electron transfer is high, the reaction proceeds through a previously unidentified single electron transfer (SET) mechanism, where an initial electron transfer occurs between the substrate and oxidant prior to CF₃group transfer. Otherwise, a CF₃radical release/electrophilic aromatic substitution (S_EAr) mechanism is followed. These studies provide valuable insights into the role of strong oxidants and potential mechanistic dichotomy in Cu‐mediated C(sp²)−H trifluoromethylation. 

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3. Reactivity of bi- and monometallic trifluoroacetates towards amorphous SiO ₂

   https://doi.org/10.1039/d2dt02822k  

   Munasinghe, Hashini N.; Imer, Marcos R.; Szlag, Regina G.; Suescun, Leopoldo; Rabuffetti, Federico A. (December 2022, Dalton Transactions)

   The reactivity of alkali–manganese( ii ) and alkali trifluoroacetates towards amorphous SiO 2 (a-SiO 2 ) was studied in the solid-state. K 4 Mn 2 (tfa) 8 , Cs 3 Mn 2 (tfa) 7 (tfaH), KH(tfa) 2 , and CsH(tfa) 2 (tfa = CF 3 COO – ) were thermally decomposed under vacuum in fused quartz tubes. Three new bimetallic fluorotrifluoroacetates of formulas K 4 Mn 3 (tfa) 9 F, Cs 4 Mn 3 (tfa) 9 F, and K 2 Mn(tfa) 3 F were discovered upon thermolysis at 175 °C. K 4 Mn 3 (tfa) 9 F and Cs 4 Mn 3 (tfa) 9 F feature a triangular-bridged metal cluster of formula [Mn 3 (μ 3 -F)(μ 2 -tfa) 6 (tfa) 3 ] 4− . In the case of K 2 Mn(tfa) 3 F, fluoride serves as an inverse coordination center for the tetrahedral metal cluster K 2 Mn 2 (μ 4 -F). Fluorotrifluoroacetates may be regarded as intermediates in the transformation of bimetallic trifluoroacetates to fluoroperovskites KMnF 3 , CsMnF 3 , and Cs 2 MnF 4 , which crystallized between 250 and 600 °C. Decomposition of these trifluoroacetates also yielded alkali hexafluorosilicates K 2 SiF 6 and Cs 2 SiF 6 as a result of the fluorination of fused quartz. The ability to fluorinate fused quartz was observed for monometallic alkali trifluoroacetates as well. Hexafluorosilicates and heptafluorosilicates K 3 SiF 7 and Cs 3 SiF 7 were obtained upon thermolysis of KH(tfa) 2 and CsH(tfa) 2 between 200 and 400 °C. This ability was exploited to synthesize fluorosilicates under air by simply reacting alkali trifluoroacetates with a-SiO 2 powder. 

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4. Copper‐Catalyzed C(sp ³ )−H α‐Acetylation: Generation of Quaternary Centers

   https://doi.org/10.1002/anie.202418692  

   Okoromoba, Otome E; Chen, Ting‐An; Jang, Eun Sil; McMullin, Claire L; Cundari, Thomas R; Warren, Timothy H (January 2025, Angewandte Chemie International Edition)

   Abstract α‐substituted ketones are important chemical targets as synthetic intermediates as well as functionalities in natural products and pharmaceuticals. We report the α‐acetylation of C(sp³)−H substrates R−H with arylmethyl ketones ArC(O)Me to provide α‐alkylated ketones ArC(O)CH₂R at RT with^tBuOO^tBu as oxidant via copper(I) ‐diketiminato catalysts. Proceeding via alkyl radicals R•, this method enables α‐substitution with bulky substituents without competing elimination that occurs in more traditional alkylation reactions between enolates and alkyl electrophiles. DFT studies suggest the intermediacy of copper(II) enolates [Cu^II](CH₂C(O)Ar) that capture alkyl radicals R• to give R−CH₂C(O)Ar outcompeting dimerization of the copper(II) enolate to give the 1,4‐diketone ArC(O)CH₂CH₂C(O)Ar. 

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5. Trifluoromethyl substitution enhances photoinduced activity against breast cancer cells but reduces ligand exchange in Ru( ii ) complex

   https://doi.org/10.1039/d1sc03213e  

   Lanquist, Austin P.; Gupta, Sayak; Al-Afyouni, Kathlyn F.; Al-Afyouni, Malik; Kodanko, Jeremy J.; Turro, Claudia (September 2021, Chemical Science)

   A series of five ruthenium complexes containing triphenyl phosphine groups known to enhance both cellular penetration and photoinduced ligand exchange, cis -[Ru(bpy) 2 (P( p -R-Ph) 3 )(CH 3 CN)] 2+ , where bpy = 2,2′-bipyridine and P( p -R-Ph) 3 represent para -substituted triphenylphosphine ligands with R = –OCH 3 (1), –CH 3 (2) –H (3), –F (4), and –CF 3 (5), were synthesized and characterized. The photolysis of 1–5 in water with visible light ( λ irr ≥ 395 nm) results in the substitution of the coordinated acetonitrile with a solvent molecule, generating the corresponding aqua complex as the single photoproduct. A 3-fold variation in quantum yield was measured with 400 nm irradiation, Φ 400 , where 1 is the most efficient with a Φ 400 = 0.076(2), and 5 the least photoactive complex, with Φ 400 = 0.026(2). This trend is unexpected based on the red-shifted metal-to-ligand charge transfer (MLCT) absorption of 1 as compared to that of 5, but can be correlated to the substituent Hammett para parameters and p K a values of the ancillary phosphine ligands. Complexes 1–5 are not toxic towards the triple negative breast cancer cell line MDA-MB-231 in the dark, but 3 and 5 are >4.2 and >19-fold more cytotoxic upon irradiation with blue light, respectively. A number of experiments point to apoptosis, and not to necrosis or necroptosis, as the mechanism of cell death by 5 upon irradiation. These findings provide a foundation for understanding the role of phosphine ligands on photoinduced ligand substitution and show the enhancement afforded by –CF 3 groups on photochemotherapy, which will aid the future design of photocages for photochemotherapeutic drug delivery. 

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