Synthesis, characterization and catalytic activity of a mononuclear nonheme copper(II)-iodosylbenzene adduct

Jeon, Hyeri; Oh, Hana; Hong, Seung-Woo

doi:10.1016/j.jinorgbio.2021.111524

Cited by 4 publications

(1 citation statement)

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“…Herein, we report the oxidation of aldehydes into carboxylic acids by a nonheme manganese(III) iodosylbenzene complex, [Mn III (TBDAP)(OIPh)(OH)] 2+ ( 1 ; TBDAP = N,N -di- tert -butyl-2,11-diaza[3.3](2,6)-pyridinophane) (Figure c). Metal iodosylarene intermediates have emerged in the metal oxo chemistry formed by using an artificial oxidant, iodosylbenzene (PhIO), and received much interest as versatile transition metal oxidants . We previously presented the synthesis of a rare mononuclear nonheme manganese(III) iodoyslbenzene species 1 with comprehensive spectroscopic and structural characterization and oxidative reactions. , In this work, the reactivity of 1 with aldehydes is newly evaluated and analyzed by kinetic studies resulting in the electrophilicity of 1 with a kinetic isotope effect (KIE) value of 2.0 in the oxidation of aldehydes.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of Aldehydes into Carboxylic Acids by a Mononuclear Manganese(III) Iodosylbenzene Complex through Electrophilic C–H Bond Activation

2023

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The oxidation of aldehyde is one of the fundamental reactions in the biological system. Various synthetic procedures and catalysts have been developed to convert aldehydes into corresponding carboxylic acids efficiently under ambient conditions. In this work, we report the oxidation of aldehydes by a mononuclear manganese(III) iodosylbenzene complex, [MnIII(TBDAP)(OIPh)(OH)]2+ (1), with kinetic and mechanistic studies in detail. The reaction of 1 with aldehydes resulted in the formation of corresponding carboxylic acids via a pre-equilibrium state. Hammett plot and reaction rates of 1 with 1°-, 2°-, and 3°-aldehydes revealed the electrophilicity of 1 in the aldehyde oxidation. A kinetic isotope effect experiment and reactivity of 1 toward cyclohexanecarboxaldehyde (CCA) analogues indicate that the reaction of 1 with aldehyde occurs through the rate-determining C–H bond activation at the formyl group. The reaction rate of 1 with CCA is correlated to the bond dissociation energy of the formyl group plotting a linear correlation with other aliphatic C–H bonds. Density functional theory calculations found that 1 electrostatically interacts with CCA at the pre-equilibrium state in which the C–H bond activation of the formyl group is performed as the most feasible pathway. Surprisingly, the rate-determining step is characterized as hydride transfer from CCA to 1, affording an (oxo)methylium intermediate. At the fundamental level, it is revealed that the hydride transfer is composed of H atom abstraction followed by a fast electron transfer. Catalytic reactions of aldehydes by 1 are also presented with a broad substrate scope. This novel mechanistic study gives better insights into the metal oxygen chemistry and would be prominently valuable for development of transition metal catalysts.

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Section: Introductionmentioning

confidence: 99%