Aerobic C–C and C–O bond formation reactions mediated by high-valent nickel species

Smith, Sofia M.; Planas, Oriol; Gómez, Laura; Rath, Nigam P.; Ribas, Xavi; Mirica, Liviu M.

doi:10.1039/c9sc03758f

Cited by 30 publications

(38 citation statements)

References 61 publications

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“…This superhyperfine pattern clearly indicates the coordination of two 4-MeO-py ligands to the Ni III center. [45][46][47][48][49] Furthermore, the signal produced by the second species strongly resembles EPR data collected for trans-Ni III (salen)(py)2 complexes. 44 The distinction between trans-(py)2 and cis-(py)2 coordination is important in the present case as both are theoretically possible.…”

Section: [Ni III (Dtc)2(l)x] + Formationmentioning

confidence: 57%

Controlling One-Electron vs Two-Electron Pathways in the Multi-Electron Redox Cycle of Nickel Diethyldithiocarbamate

Mazumder¹,

Burton²,

Richburg³

et al. 2021

Preprint

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This manuscript describes electrochemical experiments in which a Nickel(III) intermediate is kinetically trapped by the addition of derivatized pyridine ligands to the electrolyte solution. EPR and DFT studies support the conclusion that pyridine coordinates in a trans- configuration and contains a small equilibrium between mono- and bis-pyridine structures. Electrochemical kinetic data provides evidences for decomposition pathways which ultimately result in Ni(IV) complexes.

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Section: [Ni III (Dtc)2(l)x] + Formationmentioning

confidence: 57%

Controlling One-Electron vs Two-Electron Pathways in the Multi-Electron Redox Cycle of Nickel Diethyldithiocarbamate

Mazumder¹,

Burton²,

Richburg³

et al. 2021

Preprint

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“…This signal was simulated using superhyperfine coupling to two N atoms with coupling constants A123 = 13.0, 13.0, 18.0 G giving rise to quintet splitting with a 1:2:3:2:1 intensity ratio. This superhyperfine pattern clearly indicates the coordination of two 4-MeO-py ligands to the Ni III center [45][46][47][48][49]. Furthermore, the signal produced by the second species strongly resembles EPR data collected for trans-Ni III (salen)(py)2 complexes 44.…”

mentioning

confidence: 76%

Controlling One-Electron Vs Two-Electron Pathways in the Multi-Electron Redox Cycle of Nickel Diethyldithiocarbamate

et al. 2021

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The unique redox cycle of Ni II (dtc)2, where dtcis N,N-diethyldithiocarbamate, in acetonitrile displays 2eredox chemistry upon oxidation from Ni II (dtc)2 → [Ni IV (dtc)3] + but 1eredox chemistry upon reduction from [Ni IV (dtc)3] + → Ni III (dtc)3 → Ni II (dtc)2. The underlying reasons for this cycle lie in the structural changes that occur between four-coordinate Ni II (dtc)2 and sixcoordinate [Ni IV (dtc)3] + . Cyclic voltammetry (CV) experiments show that these 1eand 2e -pathways can be controlled by the addition of pyridine-based ligands (L) to the electrolyte solution. Specifically, the addition of these ligands resulted in a 1eligand-coupled electron transfer (LCET) redox wave which produced a mixture of pyridine-bound Ni(III) complexes, [Ni III (dtc)2(L)] + and [Ni III (dtc)2(L)2] + . Although the complexes could not be isolated, electron paramagnetic resonance (EPR) measurements using a chemical oxidant in the presence of 4-methoxypyridine confirmed the formation of trans-[Ni III (dtc)2(L)2] + . Density functional theory calculations were also used to support the formation of pyridine coordinated Ni(III) complexes through structural optimization and calculation of EPR parameters. The reversibility of the LCET process was found to be dependent on both the basicity of the pyridine ligand and the scan rate of the CV experiment. For strongly basic pyridines (e.g. 4-methoxypyridine) and/or fast scan rates, high reversibility was achieved, allowing [Ni III (dtc)2(L)x] + to be reduced directly back to Ni II (dtc)2 + xL. For weakly basic pyridines (e.g. 3-bromopyridine) and/or slow scan rates, [Ni III (dtc)2(L)x] + decayed irreversibly to form [Ni IV (dtc)3] + . Detailed kinetics studies using CV reveal that [Ni III (dtc)2(L)] + and [Ni III (dtc)2(L)2] + decay by parallel pathways due to a small equilibrium between the two species. The rate constants for ligand dissociation ([Ni III (dtc)2(L)2] + → [Ni III (dtc)2(L)] + + L) along with decomposition of [Ni III (dtc)2(L)] + and [Ni III (dtc)2(L)2] + species were found to increase with 2 the electron-withdrawing character of the pyridine ligand, indicating pyridine dissociation is likely the rate limiting step for decomposition of these complexes. These studies establish a general trend for kinetically trapping 1eintermediates along a 2eoxidation path.

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“…Indeed, in comparison with the neighboring elements, high-valence nickel complexes have presented significant challenges in synthetic coordinationc hemistry. [17] Consequently,w eh ypothesized that:1 )introduction of ah ighly electron-donating ligand should support formation of high-valence nickel species, and 2) an extensive conjugation system might provide an electron sink to be compatible with other steps of the desired catalytic cycle.…”

Section: Introductionmentioning

confidence: 99%

Well‐Defined, Versatile and Recyclable Half‐Sandwich Nickelacarborane Catalyst for Selective Carbene‐Transfer Reactions

Wang

Perveen

Ouyang

et al. 2021

Chemistry A European J

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Catalyticc arbene-transfer reactions constitute a class of highly useful transformations in organic synthesis. Although catalysts based on ar ange of transition-metals have been reported, the readily accessible nickel(II)-based complexes have been rarely used. Herein, an air-stable nickel(II)-carborane complex is reported as aw ell-defined, versatile and recyclable catalyst for selectivec arbene transfer reactions with low catalyst loading under mild conditions. This catalysti se ffective for several types of reactions including diastereoselectivec yclopropanation, epoxidation, selective XÀHi nsertions (X = C, N, O, S, Si), particularly for the unprotected substrates. This represents ar are example of carborane ligands in base metal catalysis.

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Aerobic C–C and C–O bond formation reactions mediated by high-valent nickel species

Abstract: Reported herein are organometallic Ni(ii) complexes that react with mild oxidants such as O2 and H2O2 and exhibit oxidatively-induced reactivity to yield C–C and C–O bond formation products via observable high-valent Ni intermediates.

Cited by 30 publications

References 61 publications

Controlling One-Electron vs Two-Electron Pathways in the Multi-Electron Redox Cycle of Nickel Diethyldithiocarbamate

Controlling One-Electron vs Two-Electron Pathways in the Multi-Electron Redox Cycle of Nickel Diethyldithiocarbamate

Controlling One-Electron Vs Two-Electron Pathways in the Multi-Electron Redox Cycle of Nickel Diethyldithiocarbamate

Well‐Defined, Versatile and Recyclable Half‐Sandwich Nickelacarborane Catalyst for Selective Carbene‐Transfer Reactions

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