Activation of C−H⋅⋅⋅Halogen (Cl, Br, and I) Hydrogen Bonds at the Organic/Inorganic Interface in Fluorinated Tetrathiafulvalenes Salts
✍ Scribed by Olivier J. Dautel; Marc Fourmigué; Enric Canadell
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 254 KB
- Volume
- 7
- Category
- Article
- ISSN
- 0947-6539
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✦ Synopsis
The electrocrystallization of fluorinated bis(2,2'-difluoropropylenedithio)tetrathiafulvalene (1) in the presence of linear (ICl 2 À , IBr 2 À , I 2 Br À ) or cluster ([Mo 6 Cl 14 ] 2À ) anions affords 1:1 and 2:1 cation radical salts such as [1][ICl 2 ] and [1] 2 [Mo 6 Cl 14 ] ´(CH 3 CN) 2 . In both salts, the 1 . radical ion adopts a boat conformation and envelops the anion through C À H ´´´Hal anion (Hal anion Cl, Br, I) hydrogen bonds. This demonstrates the activating role of the neighboring electron-withdrawing CF 2 moieties in the stabilization of bi-or trimolecular neutral entities. With smaller linear anions, fluorine segregation controls the solid-state associations of the bimolecular [1] . [X] À entities, and gives rise to layered materials with a limited overlap interaction between the open-shell organic cations and magnetic spin chain behavior. With the larger [Mo 6 Cl 14 ] 2À ions, a strong overlap interaction between radical cations gives rise to diamagnetic [1] 2 2 dimers, which alternate with the cluster anions to form hybrid organic/inorganic ´´´[1] 2 2 [Mo 6 Cl 14 ] 2À ´´ć hains. This behavior is also observed in [2] 2 2 [Mo 6 Cl 14 ] 2À ´(CH 2 Cl 2 ) 2 , in which compound 2 is the unsymmetrically substituted (ethylenedithio)(2,2'-di-fluoropropylenedithio)tetrathiafulvalene. On the other hand, the unsymmetrically substituted 2,2'-difluoropropylenedithiotetrathiafulvalene (3) affords a mixed-valence 4:1 salt with [Mo 6 Cl 14 ] 2À , which is formulated as [3] 4 [Mo 6 Cl 14 ]
´(CH 3 CN) 2 . This semiconducting salt is characterized by the coexistence of both the fluorine/fluorine segregation (with solvent inclusion) and the organic/inorganic segregation (with delocalized overlap interactions). Both C sp 2 ÀH ´´´Cl and C sp 3 ÀH ´´´Cl hydrogen bonds facilitate the stabilization of the organic/inorganic interface and the presence of conducting organic slabs.