Long‐Lived Radical Cations of Monocyclic Arenes at Room Temperature Obtained by NbF₅ Acting as an Oxidizing Agent and Counterion Precursor

Abstract

Das Salz der Erde: Eine Reaktion, in der Niobpentafluorid als Oxidationsmittel (Bildung von NbF4) und als Fluoridakzeptor (Bereitstellung des Gegenions [Nb2F11]−) fungiert, lieferte Radikalkationensalze von monocyclischen Arenen, einschließlich Benzol (siehe Bild). Anion‐π‐Wechselwirkungen sind entscheidend für die einzigartige Inertheit der Radikalkationen.

13C‐Detected Through‐Bond Correlation Experiments for Protein Resonance Assignment by Ultra‐Fast MAS Solid‐State NMR

“…[C 6 I 6 ] + , however, keeps the regular hexagonal structure,6 as predicted 9. Finally [1,4‐(CH 3 O) 2 ‐2,5‐F 2 C 6 H 2 ] + has a pronounced compressed (quinoid) structure 7…”

“…Only recently, the first of such structure determinations became available, for [C 6 F 6 ] + ,5 [C 6 F 5 H] + ,6 1,2,4,5‐[C 6 F 4 H 2 ] + ,6 1,3,5‐[C 6 F 3 H 3 ] + ,6 [C 6 Cl 6 ] + ,6 and [C 6 I 6 ] + 6. Simultaneously, the crystal structure of [1,4‐(CH 3 O) 2 ‐2,5‐F 2 C 6 H 2 ] + [Nb 2 F 11 ] – was reported 7…”

“…But parallel to this, the radical cations become less stable. The ultimate goal, isolation of [C 6 H 6 ] + , remains unreached, although ESR identification of it has been achieved, as isolated species and also assigned as a [C 6 H 6 ] + [Nb 2 F 11 ] – ion pair 7,13…”

Oligotriarylamines with a Pyrene Core: A Multicenter Strategy for Enhancing Radical Cation and Dication Stability and Tuning Spin Distribution

“…When the conventional electrolyte, nBu 4 NClO 4 , was used during the measurement of tetraamine 6, two two-electron processes at + 0.44 and + 1.21 V were observed. However, the first wave split into two when nBu 4 NB(C 6 F 5 ) 4 with weakly coordinating anions was used. [24] These waves are associated with the oxidation of both amine (N 0/ C + ) and pyrene moieties (Pyr 0/ C + ), which will be further discussed later.…”

Isolation and Characterization of the Cycloparaphenylene Radical Cation and Dication

“…Significant progress has been made in isolating and characterizing p-radical cations and dications of oligomers with well-defined structures; these are used as models for polymers. [2] For example, the radical cations of poly(para-phenylene) oligomers were prepared and characterized by Rathore and co-workers. [3] They confirmed the delocalization of the positive charge over all phenylene moieties by size-dependent UV/Vis absorption spectroscopy and X-ray crystallographic analysis of the quaterphenyl derivative; from the alternation of the bond lengths and a decrease in the dihedral angle of the two nearly coplanar para-phenylene units, an increase in the quinoidal character could be deduced.…”