Isolable Anion Radicals of Nitrosoarenes

Abstract

Summary of main observation and conclusionThe rich redox chemistry of nitrosoarenes has rendered these reactive molecules very useful in modern synthetic and material chemistry. Electrochemical studies have revealed the capability of nitrosoarenes to undergo one‐electron oxidation or reduction reaction for a long time. However, the isolation and structural characterization of nitrosoarene radical compounds deviating the stabilization of transition‐metal have not been achieved. Investigation on the reduction reaction of nitrosoarenes bearing steric demanding substituents has now revealed that the interaction of 2,6‐dimesityl‐1‐nitroso‐benzene (DmpNO) or 2,4,6‐tri(tert‐butyl)‐1‐nitroso‐benzene (TtpNO) with KC8 and crypt‐2,2,2 can produce the corresponding anion radical compound [K(crypt‐2,2,2)][DmpNO] (1) or [K(crypt‐2,2,2)][TtpNO] (2) in good isolated yield. Compounds 1 and 2 represent the first examples of isolable nitrosoarene radical compounds deviating the stabilization of transition‐metal, and have been characterized by single‐crystal X‐ray diffraction study, electron paramagnetic resonance (EPR) spectroscopy, and elemental analysis. Theoretical study in collaboration with the characterization data revealed that the unpaired spin in [DmpNO]•– and [TtpNO]•– delocalizes on the nitroso and the central phenyl groups.