Structures comparées de (NH4)2AsCr3O12(OH) et Cs2AsCr3O12(OH): Tendance à la formation d'une charpente tridimensionnelle par association d'hétéropolyanions
✍ Scribed by M. Goreaud
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 187 KB
- Volume
- 102
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
Orange single crystals of (\mathrm{Cs}{2} \mathrm{AsCr}{3} \mathrm{O}{12}(\mathrm{OH})) have been synthesized from aqueous solutions. They are monoclinic, space group (P 2{1} / c) with (a=10.544(1), b=8.098(2), c=15.362(1) \AA) and (\beta=94.006(8)^{\circ}), (Z=4). The structure, solved by the heavy-atom method, was refined to (R=0.054\left(R_{w}=0.066\right)) for 950 reflections with (\sigma(I) / I \leq 0.333). The study of the oxygen "lattice" shows the existence of more numerous (\mathrm{O}-\mathrm{O}) short distances than in the (\left(\mathrm{NH}{4}\right){2} \mathrm{AsCr}{3} \mathrm{O}{12}(\mathrm{OH})) structure and a tendency for the (\mathrm{AsCr}{3} \mathrm{O}{12}(\mathrm{OH})^{2-}) polyanions to form a three-dimensional framework from a layer structure. O 1993 Academic Press. Inc.