The development of efficient catalysts for the oxidation of substrates with large C-H bond dissociation enthalpies (BDEs) is best accomplished by understanding how nature carries out oxidations. Of particular interest is the monocopper enzyme lytic polysaccharide monooxygenase (LPMO) for its role in the hydroxylation of C-H bonds within polysaccharides. Three reactive copper-oxygen species have been postulated for LPMO: (i) a CuII-oxyl, [Cu-O]+, (ii) a CuIII-hydroxide, [Cu-OH]2+, formally considered a protonated [Cu-O]+, or (iii) a CuII-superoxide, [Cu-O2]+. Previous research in the Tolman group has characterized two mononuclear copper-oxygen complexes: a [LCuIIIOH]0 and a [LCuII-O2]- species. The [LCuIII-OH]0 complex has been shown to undergo rapid hydrogen atom transfer (HAT) in the presence of hydrocarbons while the [LCuIIO2]- complex was unable to perform HAT, instead acting as a nucleophile, in the presence of phenols. The unique reactivity of these complexes invoke important questions regarding the role of overall charge and electron-donating/withdrawing contribution of the supporting ligand in the oxidation of strong C-H bonds. The synthesis, characterization, and reactivity of copper-oxygen cores supported by a monoanionic bis(2-quinolinoylcarbonyl)amide ligand will be reported as a means to probe the effects of overall charge and coordination environment on C-H reactivity.

Probing the effect of ligand electronics on the C-H reactivity of copper-oxygen cores

253rd National Meeting (2017)

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