| Abstract
| - The reductive electrochemistry of substituted benzophenones in the aprotic room-temperature ionic liquid(RTIL) 1-butyl-1-methylpyrrolidinium bistriflimide occurs via two consecutive one-electron processes leadingto the radical anion and dianion, respectively. The radical anion exhibited electrochemical reversibility at alltime-scales whereas the dianion exhibited reversibility at potential sweep rates of ≥10 V s-1, collectivelyindicating the absence of strong ion-paring with the RTIL cation. In contrast, reduction in 1-butyl-3-methylimidazolium bistriflimide is complicated by proton-transfer from the [Bmim] cation. At low potentialsweep rates, reduction involves a single two-electron process characteristic of either an electrochemical,chemical, electrochemical (ECE) or disproportion-type (DISP1) mechanism. The rate of radical anionprotonation in [Bmim] is governed by basicity and conforms to the Hammett free-energy relation. At higherpotential sweep rates in [Bmim][NTf2], reduction occurs via two consecutive one-electron processes, givingrise to the partially reversible generation of the radical anion and the irreversible generation of the dianion,respectively. Also, the redox potentials for the reversible parent/radical anion couples were found to be alinear function of Hammett substituent constants in both RTIL media and exhibited effectively equivalentsolvent-dependent reaction constants, which are similar to those for reduction in polar molecular solventssuch as acetonitrile or alcohols.
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