Tethered CAAC–CAAC dimers: oxidation to persistent radical cations and bridging-unit dependent reactivity/stability of the dications

Abstract

CAAC–CAAC dimers with alkylene spacers are presented. These compounds are electron-rich and undergo one- and two-electron oxidation.

Disclosing Cyclic(Alkyl)(Amino)Carbenes as One‐Electron Reductants: Synthesis of Acyclic(Amino)(Aryl)Carbene‐Based Kekulé Diradicaloids

“…A similar observation was also observed when we performed the oxidation using NO 2 [BF 4 ]. During the course of the reaction, we did not observe any indication for the dimerization of 2 (dication of CAAC–CAAC dimer) [19] . This is most likely due to the steric hindrance at the N ‐center.…”

“…During the course of the reaction, we did not observe any indication for the dimerization of 2 (dication of CAAC-CAAC dimer). [19] This is most likely due to the steric hindrance at the N-center. Also, we did not observe any reaction between 1 and 3[SbF 6 ] which is in contrast with that of the N-iPr analogue.…”

Bis[cyclic (alkyl)(amino)carbene] isomers: Stable trans-bis(CAAC) versus facile olefin formation for cis-bis(CAAC)

“…S59, ESI †), corresponding to the oxidation of 8 to its radical cation and further to the dication, respectively. Both oxidations are anodicallyshifted in comparison to the values reported by Sarkar, 20 potentially due to the inductive effect of the N-aryl substituent in 8 leading to a less electron rich system. The C 2 -symmetric radical cation was isolated as purple tetrafluoroborate salt 9 following the oxidation of 8 with [Ph 3 C][BF 4 ].…”

“…Similar electron-rich olefins were recently reported by Sarkar. 20 Solutions of 8 in toluene were stable up to 110 °C and the solid could be handled in air. The substantial steric crowding in 8 forces the nitrogen atoms to become pyramidalized (sum of nitrogen bond angles 351.4(4)°).…”

Twisted Push–Pull Alkenes Bearing Geminal Cyclicdiamino and Difluoroaryl Substituents

“…Notably, the simulated UV–vis spectra of 3 and 16 based on TD-DFT calculations are in good agreement with the corresponding experimental spectra (Figure S102). The absorbance of 16 is red-shifted in comparison with electron-rich alkene-derived radical cations …”