Germanium fluorides, synthesis

Al-containing ITQ-21 zeolite ((Si+Ge)/Al=25, Si/Ge=20) was synthesized using N(16)-methyl-sparteinium cation (MSPT+) as the organic structure-directing agent in combination with fluoride anions and germanium as described in [1], The composition of the final synthesis gel was ... 

There appears to be only one really satisfactory method for preparing pure germanium(IV) fluoride. This method involves the thermal decomposition of barium hexafluoro-germanate1 in a quartz or Vycor tube, a method analogous to that described for the preparation of silicon tetrafluoride (synthesis 47). Germanium(IV) fluoride has also been produced by the fluorination of germanium(IV) chloride with antimony (III) fluoride 2 however, it is necessary to distill fractionally the mixture of chlorofluorides resulting from the reaction. 

Addition of GeC>2 enabled the first synthesis of pure polymorph C of zeolite Beta (ITQ-17 [11], Fig. 3), which was predicted by Newsam et al. [40] but also of a new family of related materials (like ITQ-16), in which the ratio of polymorphs A, B, and C can be varied [41] (in zeolite Beta polymorphs A and B are in the ratio 60 40). The structure-directing role of the Ge02 in the synthesis of polymorph C has been clearly demonstrated. Fig. 4 depicts a SEM image of the crystals of polymorph C. A number of different templates (from both the structural and sterical points of view) was tested under the same hydrothermal conditions (temperature range 135-175 °C, 15-120 h, Si/Ge 0.5-30) and in all cases pure polymorph C was synthesized despite the fluoride or hydroxide medium employed. However, in the absence of germanium zeolite Beta, with a typical intergrowth of polymorphs A and B, ZSM-12 or ITQ-4 were produced [11]. 

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