ACS Organic & Inorganic Au最新文献

With the aim of enhancing the HER activity of the previously described bioinspired [NiFe]-hydrogenase complex [L^N2S2Ni^IIFe^IICp(CO)]⁺ (LNiFe, with L^N2S2 = 2,2′-(2,2′-bipyridine-6,6′-diyl)bis(1,1′-diphenylethanethiolate) and Cp = cyclopentadienyl), the electronic structure of the L^N2S2 site has been fine-tuned. In L^OMeNiFe, the bipyridine (Bpy) unit was substituted with methoxy electron-donating groups, while in L^PhenNiFe, the Bpy unit was replaced with the 1,10-phenanthroline backbone. These complexes were fully characterized, and their HER activity was investigated. A mechanistic study was conducted by using IR and EPR spectroscopies combined with density functional theory (DFT) calculations. Both complexes act as efficient electrocatalysts to produce H₂, following an ECEC mechanism, starting from the monoreduced species. L^OMeNiFe exhibits the fastest kinetics among the series (K_obs = 1.6 × 10⁴ s^–1), attributed to its higher ΔpK_a value for the protonation step of the two-electron reduced species, [L^OMeNiFe]^–. In contrast, L^PhenNiFe exhibits the lowest overpotential, with a cathodic shift of 150 mV. This improved performance is attributed to the fact that the phenanthroline backbone is more easily reduced with respect to a bipyridine unit.

In this work, a mild NaBAr^F-mediated electrophilic trifluoromethylation of nonactivated silyl enol ethers is reported, using an Umemoto-type chloride salt thanks to a reactivity-modulation through its counter-anion. Hence, the key to success is the catalytic generation of a highly reactive Umemoto trifluoromethylating agent with the non-coordinative BAr^F₂₄ anion upon in situ anion exchange initiated by catalytic amounts of the commercially available and simple NaBAr^F₂₄ salt. This alternative method enables a selective reaction towards α-trifluoromethylated ketones under mild reaction conditions and avoids the use of stoichiometric Sn reagents, offering a practical strategy for embracing further highly demanding substrates in trifluoromethylation reactions.

New fluoroboronated materials were obtained by chemical modification of poly(VDF-co-MAF) copolymers synthesized by the radical copolymerization of vinylidene fluoride (VDF) with 2-(trifluoromethyl) acrylic acid (MAF). Two copolymers were first synthesized in dimethylcarbonate (DMC) or 1,1-difluoro-1-chloroethane as the solvents in 60% yields with molar masses of 22,000 and 12,000 g·mol^–1, respectively. Although MAF does not homopolymerize under radical initiation, this is a suitable comonomer for VDF. The transfer rates were 0.40 and 0.21 for reactions carried out in DMC and in halogenated solvent, respectively. The resulting poly(VDF-co-MAF) random copolymers were condensed with aminophenyl boronic acid pinacol ester (APBAPE) in the presence or absence of a HCl trap to obtain new fluoroboronated copolymer materials. Their ¹H, ¹¹B, ¹³C, and ¹⁹F NMR and ATR IR characterizations confirmed the successful addition of APBAPE onto the fluorinated copolymer. The thermal properties of all these original copolymers were determined. As expected, the thermal stability of poly(VDF-co-MAF.APBAPE) copolymers displayed better behavior due to the decarboxylation of acid functions in MAF units as noted in their precursors. Such novel fluoropolymers bearing boron-containing groups may have potential applications in various areas as electronics and coatings.

Nitrosoarenes are useful molecules owing to their unique electronic properties. The “NO” functional group is strongly electron-withdrawing, possessing a σ_para value greater than either the nitro or trimethylammonium functional groups. Although many methods exist for the synthesis of nitroarenes, the direct incorporation of the “NO” functional group in a single step to produce nitrosoarenes has historically received less attention. In this paper, we discuss a mild and selective method for the ipso-nitrosation of arylboronic acids and their derivatives. Depending on the substrate identity, both nitro and nitrosoarenes can be formed from arylboronic acids. To overcome substrate-controlled selectivity, we developed a one-pot, two-step procedure to exclusively produce nitrosoarenes from boronic acids with no evidence of unwanted nitroarene products. A variety of arenes and heteroarenes are selectively nitrosated in good yields via reactions run open to air and without protection from moisture.