Bimetallic copper architectures are prevalent in biological and abiological small molecule manipulation. Recent computations on particulate methane mono-oxygenase suggest mixed-valency in a bridging oxygen-containing intermediate is crucial for lowering the activation energy of methane hydroxylation; nonetheless, the extent to which the oxidation states of the adjacent copper centers influence the reactivity and electronic structure of the bridging motif remains underexplored. Herein, we present a series of homo-valent Cu(II)Cu(II) and formally mixed-valent Cu(II)Cu(I) bimetallic copper imide complexes supported by a xanthene-tethered cofacial bis(dipyrrin) scaffold. Characterization by a suite of spectroscopic techniques – including single-crystal X-ray diffraction, NIR/UV-Vis, DFT/CASSCF, EPR, SQUID, and XAS – support divergent electronic structures between the different bimetallic copper imide complexes at the imide bridgehead. In particular, whereas the Cu(II)Cu(II) complex exhibits closed-shell imide behavior and engages nucleophiles, the Cu(II)Cu(I) complex exhibits nitrene character and is competent for intramolecular C–H amination.

Divergent electronic structures and reactivity profiles in bimetallic copper imide complexes

255th National Meeting (2018)

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