One-Electron Oxidation of an Organic Molecule by B(C₆F₅)₃; Isolation and Structures of Stable Non-para-substituted Triarylamine Cation Radical and Bis(triarylamine) Dication Diradicaloid

Abstract

The methylene-bridged triphenylamine 2 has been oxidized to planar radical cation 2(•+) by B(C6F5)3 or Ag(+). Further reaction of 2(•+)[Al(ORF)4](-) and 2 with trace amounts of silver salt resulted in dication 3(2+), providing a rare example of structurally characterized bis(triarylamine) "bipolarons". 3(2+) can be directly prepared by the reaction of 3 with 2 equiv of Ag(+). X-ray structural analysis together with theoretical calculation shows that 3(2+) has singlet diradical character and is analogous to Chichibabin's hydrocarbons.

Kekulé versus Lewis: When Aromaticity Prevents Electron Pairing and Imposes Polyradical Character

“…As this series of extended p-quinodimethanes has been studied from Heisenberg-Hamiltonian methods (which do not suffer from spin contamination problems), [27] it will be interesting to compare their geometries and excitation energies with the present DFT results. If substituted by four phenyl groups at their terminal ends, these molecules are known as Thiele's, [28] Chichibabin's, [29][30][31][32][33] and Müller's [34,35] hydrocarbons, respectively. The first member of the series, para-quinodimethane or para-xylylene, 1, is expected to adopt a clear quinonic structure.…”

meso–meso‐Linked Diarylamine‐Fused Porphyrin Dimers

“…The decreased aromaticity and sharp 1 HNMR signals suggest that 11 is not an open-shell diradicaloid,b ut ac losed-shell molecule of aq uinonoidal electronic structure. [15] In contrast, the oxidation of 9 with Magic Blue followed by treatment with hydrazine monohydrate furnished meso-meso, analysis ( Figure3). The two porphyrin units were almost coplanar with as mall dihedral angle of 9.28,a lthough they were slightly distorted by intramolecular steric repulsion att he opposite side of the b-b linkage.…”

Wurster‐Type Nanographenes as Stable Diradical Dications

“…Their interesting properties have fueled their development for potential applications in optoelectronics, [1,2] nonlinearo ptics, [3,4] spintronics [5] and organic photovoltaics. [9][10][11][12][13][14][15][16] Aminiumi ons are isoelectronic to carbon and the highere lectronegativity of the nitrogen atom contributes to their high stability in the biradicalf orm. [9][10][11][12][13][14][15][16] Aminiumi ons are isoelectronic to carbon and the highere lectronegativity of the nitrogen atom contributes to their high stability in the biradicalf orm.…”