STUDIES ON POLYHALIDES - 31 - ON 1,1'-DIM ETHYLFERRICINIUMPOLYIODIDES[(MEH4C5)(2)FE]I-X WITH X=3, 5 - PREPARATION AND CRYSTAL-STRUCTURES OF A TRIIODIDE (DIMEFC)I-3 AND A PENTAIODIDE (DIMEFC)I-5

Dimethylferrocene (diMeFc) may be oxidized by iodine analogous to ferr ocene (Fc) and decamethylferrocene (DMFc) to the dimethylferrocenium i on (diMeFc)(+) and precipitated as crystalline solids dimethylferrocen ium triiodide (diMeFc)I-3, dimethylferrocenium pentaiodide (diMeFc)I-5 and dimethylferrocenium heptaiodide (diMeFc)I-7. The two compounds wi th higher iodine content are new The first two compounds are character ized by X-ray diffraction methods on single crystals. The structures a re built up from complex cations with ecliptic conformation and isolat ed triiodide ions or remarkably concatenated pentaiodide ions. Dimethy lferrocenium triiodide C12H14FeI3 crystallizes triclinically in P (1) over bar with a=743.3(2) pm, b=796.8(2) pm, c=1471.7(4) pm, alpha=98.5 3(2)degrees, beta=97.30(2)degrees, gamma=109.50 degrees and Z=2. The a lready known simple crystal structure may now be described without dis ordered anions. Dimethylferrocenium pentaiodide C12H14FeI5 crystallize s orthorhombically in Pnna with a=1807.7(6) pm, b=1543.4(10) pm, c=141 3.0(11) pm and Z=8. The crystal structure contains pentaiodide chains (1)(infinity)[I-3(-). I-2] with alternating planar and helical regions .