ChemInform Abstract: Pb2Fe2Ge2O9, the Germanate Analogue of the Silicate Mineral Melanotekite.

✍ Scribed by J. BARBIER; D. LEVY

• Publisher: John Wiley and Sons
• Year: 2010
• Weight: 32 KB
• Volume: 29
• Category: Article
• ISSN: 0931-7597
• DOI: 10.1002/chin.199816006

✦ Synopsis

Pb 2 Fe 2 Ge 2 O 9 , the Germanate Analogue of the Silicate Mineral Melanotekite.

-Single crystals of the title compound are prepared by reaction of MgFe 2 Ge 2 O 8 (prereacted at 1398 K) and GeO 2 in a PbO/B 2 O 3 flux (1323 K, 5 h). The single crystal of composition Pb 2 Fe 1.78 Ge 2.11 Mg 0.11 O 9 crystallizes in the orthorhombic space group Pbcn with Z = 4. The structure exhibits an unsymmetrical splitting of the Pb site and a strong anisotropy of the bridging O atom of the Ge 2 O 7 group, which was also observed in the mineral melanotekite, Pb 2 Fe 2 Si 2 O 9 . These structural features can be associated with the stereoactivity of the Pb 2+ lone pairs, which is more pronounced in the silicate structure. -(BARBIER,