期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 144, 期 33, 页码 15372-15382出版社
AMER CHEMICAL SOC
DOI: 10.1021/jacs.2c06831
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资金
- University of Edinburgh
The Ni/Ir-photocatalyzed coupling of ArBr with RBr was studied using in situ LED -F-19 NMR spectroscopy. Factors such as light, ArBr, Ni, and Ir were found to control the rate of ArBr consumption, while [(TMS)3SiH] and RBr independently controlled the product selectivity. The major resting state of nickel was identified as ArNiII(L)Br, and the complex undergoes Ir-photocatalyzed conversion to products in competition with the release of ArBr.
The Ni/Ir-photocatalyzed coupling of an aryl bromide (ArBr) with an alkyl bromide (RBr) has been analyzed using in situ LED -F-19 NMR spectroscopy. Four components (light, [ArBr], [Ni], [Ir]) are found to control the rate of ArBr consumption, but not the product selectivity, while two components ([(TMS)3SiH], [RBr]) independently control the product selectivity, but not the rate. A major resting state of nickel has been identified as ArNiII(L)Br, and C-13-isotopic entrainment is used to show that the complex undergoes Ir-photocatalyzed conversion to products (Ar-R, Ar-H, Ar-solvent) in competition with the release of ArBr. A range of competing absorption and quenching effects lead to complex correlations between the Ir and Ni catalyst loadings and the reaction rate. Differences in the Ir/Ni Beer-Lambert absorption profiles allow the rate to be increased by the use of a shorter-wavelength light source without compromising the selectivity. A minimal kinetic model for the process allows simulation of the reaction and provides insights for optimization of these processes in the laboratory.
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