The chameleon-like nature of elusive cobalt–oxygen intermediates in C–H bond activation reactions

Abstract

High-valent metal-oxo (M–O, M = Fe, Mn, etc.) species are the well-known reaction intermediates that are responsible for a wide range of pivotal oxygenation and water oxidation in metalloenzymes. Though...

Theoretical investigation on the elusive structure–activity relationship of bioinspired high-valence nickel–halogen complexes in oxidative fluorination reactions

“…2a) of C–H bond activation by bare 1 F , we can see that binding of Lewis acid AgF enhances the oxidative ability by decreasing the activation energy with 6.3 kcal mol −1 , which is consistent with the positive effect of the Sc 3+ ion on the oxidative enhancement of the Mn IV O–Sc(OTf) 3 species reported by Nam and his coworkers. 52,53,59 The energy barrier (7.1 kcal mol −1 ) in the C–H bond activation of CHD by 1 F–Ag–F is comparable to those (5.5–9.5 kcal mol −1 ) in CHD oxidation by the high-valence metal-oxo complexes, and that (13.4 kcal mol −1 ) by the bare Ni( iii )–F species 1 F is relatively high. 52,60–62…”

“…52,53,59 The energy barrier (7.1 kcal mol −1 ) in the C–H bond activation of CHD by 1 F–Ag–F is comparable to those (5.5–9.5 kcal mol −1 ) in CHD oxidation by the high-valence metal-oxo complexes, and that (13.4 kcal mol −1 ) by the bare Ni( iii )–F species 1 F is relatively high. 52,60–62…”

“…52,53,59 The energy barrier (7.1 kcal mol −1 ) in the C-H bond activation of CHD by 1 F-Ag-F is comparable to those (5.5-9.5 kcal mol −1 ) in CHD oxidation by the high-valence metal-oxo complexes, and that (13.4 kcal mol −1 ) by the bare Ni(III)-F species 1 F is relatively high. 52,[60][61][62] Fig. 7 shows the chemo-selectivity of desaturation and fluorination of the carbon-centered CHD-H radical by the two fluorine atoms F p and F d of 1 F-Ag-F .…”

“…Since AgF is a Lewis acid, one of our authors found that binding of Lewis acids (e.g., Sc 3+ ion) to the high-valence metal-oxygen species can dramatically alter the redox ability and selectivity. 18,[52][53][54][55][56][57] The achievement of Lewis-acid binding metal-oxygen chemistry inspires us to propose a new active species, AgF-binding highvalence nickel(III)-fluorine 1 F-Ag-F (Fig. 5), which serves as an oxidant in C-H bond activation and as a fluorine donor in C-H fluorination.…”

Theoretical study of the formation of metal–oxo species of the first transition series with the ligand 14-TMC: driving factors of the “Oxo Wall”

“…[31][32][33][34][35][36][37][38][39] The chemistry of high-valent metal-oxo species of early transition metals is well known, while cobalt/nickel/copper species are expected to form their oxo intermediate during catalytic reactions, but experimental characterization of these species is very difficult due to their reactive nature and very short lifetime. [40][41][42][43][44] Many efforts have been made for the detection of terminal high-valent metal-oxo species that are involved in efficient oxidation catalysts based on late transition metals such as cobalt, nickel, and copper. [45][46][47][48][49][50] This is related to the concept of the "Oxo Wall".…”