TY - JOUR

T1 - Dimer Radical Anions of Polyfluoroarenes. Two More to a Small Family

AU - Beregovaya, Irina V.

AU - Shchegoleva, Lyudmila N.

AU - Ovchinnikov, Dmitry A.

AU - Blinkova, Svetlana V.

AU - Borovkov, Vsevolod I.

AU - Andreev, Rodion V.

AU - Bagryansky, Victor A.

AU - Molin, Yuri N.

N1 - Publisher Copyright: Copyright © 2019 American Chemical Society. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2019/12/26

Y1 - 2019/12/26

N2 - While there is a body of experimental data concerning dimers formed by an aromatic molecule and its radical cation, information on the corresponding dimer radical anions (DRAs) is scarce. In this work, evidence for the formation of the DRAs of decafluorobiphenyl and 4-aminononafluorobiphenyl has been obtained by the optically detected electron paramagnetic resonance and the time-resolved magnetic field effect techniques. Theoretical investigation (DFT B3LYP-D3/6-31+G*) of these DRAs and the DRAs of octafluoronaphtalene and 1,2,4,5-tetrafluorobenzene previously detected by Werst has been undertaken to gain greater insight into the structure of the polyfluoroarene DRAs. Without substituents different from a fluorine atom, an extra electron is evenly delocalized over two fragments; the bonding interaction is πstacking. On the potential energy surfaces (PES), there are two minima of nearly equal energy corresponding to the structures of perfect and parallel displaced sandwiches. Such a PES structure is due to a conical intersection between two electronic states of different symmetry. The DRA of 4-aminononafluorobiphenyl is an ion-molecular associate stabilized by electrostatic interactions involving NH2 groups. The complex cyclic structure of the PES of this DRA suits the successive electron transfers between the dimer fragments. The calculated hyperfine coupling constants averaged over the PES minima agree well with the experimental ones.

AB - While there is a body of experimental data concerning dimers formed by an aromatic molecule and its radical cation, information on the corresponding dimer radical anions (DRAs) is scarce. In this work, evidence for the formation of the DRAs of decafluorobiphenyl and 4-aminononafluorobiphenyl has been obtained by the optically detected electron paramagnetic resonance and the time-resolved magnetic field effect techniques. Theoretical investigation (DFT B3LYP-D3/6-31+G*) of these DRAs and the DRAs of octafluoronaphtalene and 1,2,4,5-tetrafluorobenzene previously detected by Werst has been undertaken to gain greater insight into the structure of the polyfluoroarene DRAs. Without substituents different from a fluorine atom, an extra electron is evenly delocalized over two fragments; the bonding interaction is πstacking. On the potential energy surfaces (PES), there are two minima of nearly equal energy corresponding to the structures of perfect and parallel displaced sandwiches. Such a PES structure is due to a conical intersection between two electronic states of different symmetry. The DRA of 4-aminononafluorobiphenyl is an ion-molecular associate stabilized by electrostatic interactions involving NH2 groups. The complex cyclic structure of the PES of this DRA suits the successive electron transfers between the dimer fragments. The calculated hyperfine coupling constants averaged over the PES minima agree well with the experimental ones.

KW - ELECTRON-SPIN-RESONANCE

KW - ABSORPTION-SPECTRA

KW - CATIONS

KW - FLUORESCENCE

KW - BENZENE

KW - PAIRS

KW - IONS

KW - EPR

UR - http://www.scopus.com/inward/record.url?scp=85076635237&partnerID=8YFLogxK

U2 - 10.1021/acs.jpca.9b09906

DO - 10.1021/acs.jpca.9b09906

M3 - Article

C2 - 31769681

AN - SCOPUS:85076635237

VL - 123

SP - 10968

EP - 10975

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

SN - 1089-5639

IS - 51

ER -