| Abstract
| - Mixed-valence states and crystal structures for[FcC7H15]2I3 and[FcC8H17]2I3 wereinvestigated. They showed the different mixed-valence statesdespite both having unsymmetrical triiodide anion. The importanceof the cation−cation interaction was suggested in the mixed-valencestate.
- X-ray powder diffraction patterns revealed that1‘,1‘‘‘-diheptyl- and 1‘,1‘‘‘-dioctyl-1,1‘‘-biferroceniumtriiodidesobtained from hexane and from dichloromethane have a layered structurewith longer interlayer distances. 1‘,1‘‘‘-Diheptyl-1,1‘‘-biferrocenium triiodide falls under the category reportedbefore, while 1‘,1‘‘‘-dioctyl-1,1‘‘-biferrocenium triiodide becomes exception; it shows a valence detrappingwith increasing temperature despitethe longer interlayer series. The difference in the crystalstructure between longer and shorter interlayer distanceseries was reflected in the difference of the space group.1‘,1‘‘‘-Diheptyl-1,1‘‘-biferrocenium triiodide(C34H46Fe2I3) crystallizes in the monoclinic spacegroup P21/c with unit cell parametersa = 27.209(10) Å, b =9.6480(6) Å, c = 14.042(10) Å, β = 98.572(4)°,and Z = 4, while 1‘,1‘‘‘-dioctyl-1,1‘‘-biferroceniumtriiodide(C36H50Fe2I3)crystallizes in the monoclinic space groupP21/c with a =20.758(6) Å, b = 9.80(1) Å, c =37.88(2) Å, β =90.44(3)°, and Z = 8. Both salts in thepresent study have a space group ofP21/c, which is different fromtheshorter interlayer series; 1‘,1‘‘‘-dihexyl- and1‘,1‘‘‘-didodecyl-1,1‘‘-biferrocenium triiodides have a space groupofP1̄. The difference in the structure between the1‘,1‘‘‘-diheptyl derivative and the 1‘,1‘‘‘-dioctyl derivative isalsodiscussed. There is a difference in the symmetry of the monocationbetween the two salts, while both show theunsymmetrical triiodide anion. The difference between them makesthe difference of the cation−cation interaction.The structure of the cations agrees with the result of57Fe Mössbauer spectroscopy. Thecation−cation interactionin the stacking is observed in 1‘,1‘‘‘-dioctyl derivative, while suchinteraction is disturbed by the adjacent stackingin 1‘,1‘‘‘-diheptyl derivative.
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