jz8b01128_si_002.cif (748.28 kB)
Modern Spin on the Electrochemical Persistence of Heteroatom-Bridged Triphenylmethyl-Type Radicals
dataset
posted on 2018-05-11, 00:00 authored by David
T. Hogan, Todd C. SutherlandHerein
we present a clarification of the ambiguous persistence
of the 10-methyl-9-phenylacridanyl, 9-phenylxanthenyl, and 9-phenylthioxanthenyl
radicals in electrochemical experiments. Each of these radicals has
separately been the subject of conflicting literature results for
decades with publications claiming both their chemical inertness and
propensity to dimerize. We assert that each radical is persistent
at conventional electrochemical time scales up to several minutes
based on reversible redox couples and cyclic voltammogram simulations
of the radicals and their respective cations. All three radicals are
rapidly consumed by aerial O2, which lends irreversibility
to the redox couples after fewer than 20 s of exposure to air. With
appreciation for the O2 sensitivity of these radicals,
their electrochemically generated UV–visible absorption spectra
have been acquired and matched to predictions made by TD-DFT calculations.
Further, we propose that previous claims to have electrochemically
measured radical–radical dimerizations have only observed reaction
of these radicals with dissolved O2.