279216-45-4Relevant articles and documents
Electron acceptors of the fluorene series. 10. Novel acceptors containing butylsulfanyl, butylsulfinyl, and butylsulfonyl substituents: Synthesis, cyclic voltammetry, charge-transfer complexation with anthracene in solution, and X-ray crystal structures of two tetrathiafulvalene complexes
Perepichka, Igor F.,Popov, Anatolii F.,Orekhova, Tatyana V.,Bryce, Martin R.,Andrievskii, Alexander M.,Batsanov, Andrei S.,Howard, Judith A. K.,Sokolov, Nikolai I.
, p. 3053 - 3063 (2000)
2,4,5,7-Tetranitro-9-fluorenone (1b) reacts readily with n-butanethiol in dipolar aprotic solvents with selective substitution of nitro groups by butylsulfanyl groups in positions 2 and 7 (2, 3); the 2,5-isomer 4 was formed only as a minor product (a fourth reduction wave, representing reversible tetraanion formation. Substitution of the oxygen of the carbonyl group in the fluorenones by a dicyanomethylene group increased the thermodynamic stability (K(SEM) growth) of the radical anion; K(SEM) ranged from 3 x 105 to 3 x 109 M-1. CV measurements characterize compounds 3, 4 (EA = 1.86-1.89 eV) as poor acceptors, 2, 6-11 (EA = 2.13-2.31 eV) as moderate acceptors, and 5, 12- 15 (EA = 2.53-2.66 eV) as strong electron acceptors. Charge-transfer complex (CTC) formation between acceptors 9, 10, 13, 14, and anthracene as a donor was monitored by the appearance of additional low-energy bands in the visible region (CTC bands) of their electron absorption spectra. Increasing the EA of the acceptors from 9-fluorenones to the corresponding 9- dicyanomethylenefluorenes increases the complexation constants K(CTC) by 2.5- 3 times, while sulfonyl substituents present substantial steric hindrance for complexation (as compared to the nitro group), decreasing K(CTC) values. Two CTCs for acceptors 14 and 17 with tetrathiafulvalene (TTF) were obtained, and their structures were solved by single-crystal X-ray diffractometry, giving the stoichometries 14:TTF, 2:3, and 17:TTF:PhCl, 1:1:0.5. In the former complex the packing motif is a mixed ... DDAD'A ... stack; in the latter complex the D and A moieties form unusually close CT pairs, which pack in a herringbone motif.
