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Characterization and reactivity of a terminal nickel(III)-oxygen adduct

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High-valent terminal metal-oxygen adducts are hypothesized to be the potent oxidizing reactants in late transition metal oxidation catalysis. In particular, examples of high-valent terminal nickel-oxygen adducts are scarce, meaning there is a dearth in the understanding of such oxidants. A monoanionic NiII-bicarbonate complex has been found to react in a 1:1 ratio with the one-electron oxidant tris(4-bromophenyl)ammoniumyl hexachloroantimonate, yielding a thermally unstable intermediate in high yield (ca. 95%). Electronic absorption, electronic paramagnetic resonance, and X-ray absorption spectroscopies and density functional theory calculations confirm its description as a low-spin (S = 1/2 ), square planar NiIII-oxygen adduct. This rare example of a high-valent terminal nickel-oxygen complex performs oxidations of organic substrates, including 2,6-di-tert-butylphenol and triphenylphosphine, which are indicative of hydrogen atom abstraction and oxygen atom transfer reactivity, respectively

This publication has emanated from research supported in part by the European Union (FP7-333948, AMcD), a research grant from Science Foundation Ireland (SFI/12/RC/2278, AMcD), and COST Action CM1305 (ECOSTBio). M.S. acknowledges MINECO (CTQ2011-25086/BQU), DIUE of the Generalitat de Catalunya (2014SGR1202), MICINN (Ministry of Science and Innovation, Spain), the FEDER fund (UNGI08-4E-003) and CESCA. Operation of NSLS X3B is supported by NIH grant P30-EB-009998. The NSLS is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract no. DE-AC02-98CH10886

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