We report the discovery that perfunctionalized icosahedral dodecaborate clusters of the type B12(OCH2Ar)12 (Ar = Ph or C6F5) can act as powerful metal-free photooxidants. These cluster compounds, when irradiated with blue LED light, exhibit excited state reduction potentials as high as ~3 volts vs. SCE, making them the strongest molecular photooxidants known to date. Photo-excitation occurs as a result of charge transfer between low-lying orbitals of the benzyl substituents and an unoccupied orbital delocalized throughout the boron cluster core. We show that these species are able to participate in electron transfer processes with a broad range of electron-rich and electron-deficient styrene substrates, initiating their polymerization at cluster loadings as low as 0.005 mol%. Furthermore, photo-excitation of B12(OCH2C6F5)12 in the presence of isobutylene, a less activated olefin, results in the production of highly branched poly(isobutylene). This work introduces a new class of robust, metal-free photo-redox reagents capable of mediating chemical transformations.

B12(OR)12 Reagents as tunable one-electron oxidants

253rd National Meeting (2017)

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