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- ItemQuinoidal Azaacenes: 99 % Diradical Character(Weinheim : Wiley-VCH Verlag, 2020) Intorp, S.N.; Hodecker, M.; Müller, M.; Tverskoy, O.; Rosenkranz, M.; Dmitrieva, E.; Popov, A.A.; Rominger, F.; Freudenberg, J.; Dreuw, A.; Bunz, U.H.F.Quinoidal azaacenes with almost pure diradical character (y=0.95 to y=0.99) were synthesized. All compounds exhibit paramagnetic behavior investigated by EPR and NMR spectroscopy, and SQUID measurements, revealing thermally populated triplet states with an extremely low-energy gap ΔEST′ of 0.58 to 1.0 kcal mol−1. The species are persistent in solution (half-life≈14–21 h) and in the solid state they are stable for weeks.
- ItemElectron-transfer initiated nucleophilic substitution of thiophenolate anion by 1-chloro-substituted 4-(thiazol-2-ylazo)naphthalenes(Amsterdam : Elsevier B.V., 2020) Dmitrieva, E.; Yu, X.; Hartmann, H.In this work, the electrochemical transformation of 5-chloro-2-[(4-chloronaphthalen-1-yl)azo]thiazoles (A) into the corresponding radical anion A·− and its subsequent reaction with diphenyldisulfide (PhSSPh) was studied. It was found that the primarily generated azo anion radical A·− is able to initiate an electron transfer process which converts the disulfide into its thiolate anion PhS−. This anion was subsequently able to substitute the Cl- and H-groups by phenylmercapto moieties in the starting azo compound A. The structures of the phenylmercapto-substituted azo compounds thus generated were confirmed by thin-layer chromatography and mass spectrometry using independently prepared compounds as references.