La base faible ClO4− et la chimie du ligand perchlorato. Synthèse et analyse structurale de complexes de germanium(IV): GeCl3ClO4, GeCl2(ClO4)2 et (ClO2)2Ge(ClO4)6

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Reaction of Cl2O6 with an excess of GeCl4 at room temperature yields a colorless liquid, a complex mixture. Fractional distillation leads to GeCl3ClO4 and GeCl2(ClO4)2. (ClO2)2Ge(ClO4)6, a yellow-orange solid, is obtained by reacting excess Cl2O6 with GeCl4. It sublimes into unstable crystals above 32 °C. Vibrational spectroscopy shows mainly unidentate perchlorato groups strongly bonded to Ge in the three compounds characterized. Ge is tetrahedrally surrounded in GeCl3ClO4 while it is octahedrally surrounded in the other complexes. GeCl2(ClO4)2 and (ClO2)2Ge(ClO4)6 are individual entities while GeCl2(ClO4)2 has a polymeric structure with Ge–Cl–Ge bridges. The structure of (ClO2)2Ge(ClO4)6 is analogous to that found for (ClO2)2Sn(ClO4)6. Six unidentate perchlorato groups surround the core atom; some of them interact with ClO2+, defining a new mode of coordination for ClO4 groups. Keywords: germanium, chlorine trioxide, perchlorato, syntheses, vibrational spectroscopy.