Redox properties and radical anions of fluorinated 2,1,3‐benzothia(selena)diazoles and related compounds

Abstract

In comparison with 2,1,3‐benzothia(selena)diazoles, electrochemical oxidation and reduction of their 4,5,6,7‐tetrafluoro derivatives and a number of related compounds were studied by cyclic voltammetry. For nine examples of this class, the first reduction peaks are reversible and corresponding radical anions (RAs) are long‐lived at 295 K in MeCN and especially in DMF. The oxidation peaks were irreversible and corresponding radical cations were not observed. Electrochemically generated RAs were characterized by EPR measurements and DFT calculations at the UB3LYP/6‐31+G(d) level. The spin density distribution in the RAs is analyzed in connection with effects of S substitution by Se and/or H by F. The prospects of the studied RAs in the design and synthesis of magnetically active materials are discussed. Copyright © 2010 John Wiley & Sons, Ltd.

Electrochemical reduction, radical anions, and dehalogenation of fluorinated/chlorinated 2,1,3-benzothia/selenadiazoles

“…5 and 6; the EPR spectrum of product of ECR of 3 in MeCN was reported earlier. 2 Experimental and DFT-calculated isotropic hyperfine coupling (hfc) constants are in reasonable agreement. The EPR spectrum of RA 3 for MeCN was reported earlier.…”

“…Hydrogen replacement by fluorine affects many properties of (hetero) aromatics including (hetero) aromaticity itself. 28 Particularly, it enlarges EA1 of 2,1,3-benzothia/selenadiazoles, 2,3 i.e. their electron-acceptor ability, which can be used in the design of functional materials.…”

“…29,30 Since redox properties of compounds are of general significance for organic chemistry and its applications, 31 in this work we report on electrochemical reduction (ECR) of new fluorinated 2,1,3-benzothia/selenadiazoles bearing also chlorine and some other substituents (1-20, Figure 1), studied by cyclic voltammetry (CV), as well as on their persistent RAs characterized by EPR spectroscopy and DFT calculations. Compounds 3 and 12 together with their RAs have been characterized earlier 2 as well as related fluorinated 1,4-benzodiazines (quinoxalines) and their RAs. 32 For some derivatives, chalcogen-and halogen-dependent dehalogenation was observed being of special chemical interest.…”

Fused 1,2,3‐Thiaselenazoles Synthesized from 1,2,3‐Dithiazoles through Selective Chalcogen Exchange

“…Recently DFT and MP2 calculations and cyclic voltammetry measurements showed that in 1,2,5‐thiadiazoles and their fused derivatives replacement of S by Se enlarges the positive electron affinity ( EA 1 ), which means that the Se compounds are stronger electron acceptors than their S congeners . This trend contradicts EA 1 and Allen electronegativity of S and Se, but can be tentatively explained by the better spin/charge delocalization in the more‐diffuse π MOs of the heavier chalcogen derivatives.…”

[1,2,5]Selenadiazolo[3,4‐b]pyrazines: Synthesis from 3,4‐Diamino‐1,2,5‐selena­diazole and Generation of Persistent Radical Anions

“…According to the gas-phase (U)B3LYP/6-31+G(d) calculations, the first adiabatic electron affinity (EA) of compounds 5g and 5c are 1.55 and 1.93 eV, respectively, as compared with 0.22 eV for 1,2,5-selenadiazole and 1.06 eV for 2,1,3-benzoselenadiazole (10). [7] In the potential range 0 --2 V, the cyclic voltammogram (CV) of 5g contains three reduction peaks Ep Ep 1C = −1.40 V. [30] For both 5g and 5c the first reduction peak is H decoupling during acquisition. Spectra were acquired with recycle intervals of between 5 and 55 s, depending on the longitudinal relaxation time of the samples.…”