Differences in chemoselectivity in olefin oxidation by a series of non-porphyrin manganese(iv)-oxo complexes

Abstract

High valent metal-oxo intermediates are versatile oxidants known to facilitate both oxygen atom transfer (OAT) and hydrogen atom transfer (HAT) reactions in nature.

Enhanced Understanding of Structure–Function Relationships for Oxomanganese(IV) Complexes

“…Thermodynamic Contributions to Reactivity for Mn IV -Oxo Complexes. We have previously observed correlations between thermodynamic parameters and the reactivity of Mn IV -oxo complexes, 28 and the new data reported here for [Mn IV (O)(N3pyQ)] 2+ and [Mn IV (O)(N4py Me2 )] 2+ allow us to evaluate the robustness of these correlations. We still observe an excellent linear correlation between the rates of thioanisole oxidation (as log(k 2 )) and the DFT-calculated Mn IV �O BDFE when considering the new complexes (Figure 12, top, and Table S9).…”

“…15 While the multistate reactivity model has been extremely useful in developing and understanding the reactivity of Mn IVoxo complexes, in a recent study, we showed that the trend in C−H bond oxidation rates for these complexes can also be understood in terms of thermodynamic properties. 28 Specifically, the log k 2 for 9,10-dihydroanthracene (DHA) oxidation showed a linear correlation with the strength of the O−H bond in the Mn III -hydroxo products (Figure 1, right). A correlation was also found between oxygen-atom transfer rates and the Mn�O bond strength of Mn IV -oxo complexes.…”

“…A correlation was also found between oxygen-atom transfer rates and the Mn�O bond strength of Mn IV -oxo complexes. 28 More broadly, thermodynamic driving force has emerged as a general model to interpret oxidation reactions of oxometal species. 29 While such O−H and Mn�O bond dissociation free energies (BDFEs) can be quite challenging to measure experimentally, density functional theory (DFT) methods can reasonably predict such values, especially with proper referencing.…”

“…A similar approach was employed to calculate Mn�O BDFEs for the Mn IV -oxo complexes [Mn IV (O)(N3pyQ)] 2+ and [Mn IV (O)-(N4py Me2 )] 2+ , as described in detail in a previous publication. 28 All DFT calculations were performed using the ORCA 4.2.1 software package 47 with the B3LYP functional, 48,49 D3 dispersion correction, 50 RIJCOSX approximation, and def2/J auxiliary basis sets. Geometry optimizations and frequency calculations employed the def2-SVP basis set for all C and H atoms and the larger def2-TZVP basis set for Mn, O, and N atoms.…”

Solvent-free oxidation of benzyl C–H to ketone with Co–Ni layered double hydroxide as the catalyst and O2 as the sole oxidant

“…The selective oxidation of the C-H bond is one of the most common processes to produce high-value-added chemicals, such as hydroperoxides, alcohols, ketones, aldehydes, carboxylic acids and epoxides. [1][2][3][4][5] For example, acetophenone is an important raw material for the production of drugs, spices, resins, flavoring agents and many other drugs, and can be produced through the oxidation of ethylbenzene. 6 However, industrial acetophenone is mainly synthesized by the decomposition of cumene hydroperoxide or Friedel-Crafts acylation reaction.…”