Hydrogen Atom Transfer by a High-Valent Nickel-Chloride Complex.
Prasenjit MondalPaolo PirovanoAnkita DasErik R FarquharAidan R McDonaldPublished in: Journal of the American Chemical Society (2018)
Oxo-metal-halide moieties have often been implicated as C-H bond activating oxidants with the terminal oxo-metal entity identified as the electrophilic oxidant. The electrophilic reactivity of metal-halide species has not been investigated. We have prepared a high-valent nickel-halide complex [NiIII(Cl)(L)] (2, L = N,N'-(2,6-dimethylphenyl)-2,6-pyridinedicarboxamide) by one-electron oxidation of a [NiII(Cl)(L)]- precursor. 2 was characterized using electronic absorption, electron paramagnetic resonance, and X-ray absorption spectroscopies and mass spectrometry. 2 reacted readily with substrates containing either phenolic O-H or hydrocarbon C-H bonds. Analysis of the Hammett, Evans-Polanyi, and Marcus relationships between the determined rate constants and substrate pKa, X-H bond dissociation energy, and oxidation potential, respectively, was performed. Through this analysis, we found that 2 reacted by a hydrogen atom transfer (HAT) mechanism. Our findings shine light on enzymatic high-valent oxo-metal-halide oxidants and open new avenues for oxidative halogenation catalyst design.
Keyphrases
- electron transfer
- solar cells
- mass spectrometry
- hydrogen peroxide
- reduced graphene oxide
- high resolution
- molecular dynamics
- perovskite solar cells
- minimally invasive
- signaling pathway
- magnetic resonance imaging
- risk assessment
- nitric oxide
- room temperature
- transition metal
- data analysis
- single molecule
- simultaneous determination