Lytic polysaccharide monooxygenase (LPMO) metalloenzymes activate strong C-H bonds (~100 kcal/mol) of polysaccharides such as cellulose. Nature has evolved the ability to perform these thermodynamically difficult processes within LPMO using an active site composed of a single copper ion coordinated to the protein in a T-shaped geometry referred to as the histidine brace. Inspiration from LPMOs has led to the development of synthetic systems to perform multi-electron chemistry using copper complexes. Toward this goal, a four-coordinate Cu(II) aqua complex with a redox-active ligand, (ibaps)3-, has been developed and investigated. The [Cu(II)(ibaps)(OH2)]- complex exhibits two reversible oxidation events, the first of which has been chemically accessed. Absorption and parallel-mode EPR spectroscopies suggest the product of oxidation to have ferromagnetic coupling between the Cu(II) center and a ligand-based radical. Deprotonation of the aqua ligand to give the analogous hydroxido compound has also been pursued at the Cu(II) and oxidized levels.

Mononuclear Cu-aqua and -hydroxido complexes for multielectron processes

2019 Fall National Meeting

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