The thermal dehydration of Cs{sub 3}LnCl{sub 6}{center_dot}3H{sub 2}O to Cs{sub 3}LnCl{sub 6} (Ln=La-Nd) and their crystal structures
- Univ. Gh Kassel (Germany)
The crystal structure of Cs{sub 3}LaCl{sub 6}{center_dot}3H{sub 2}O has been determined by X-ray single crystal analysis. The compound crystallizes from aqueous solution by evaporation at 50{degrees}C in the orthorhombic space group Pnma (a = 2124.2(7)pm, b = 865.8(2) pm, and c = 852.3(2) pm, Z=4). The coordination polyhedra of lanthanum are slightly distorted trigonal prisms triply capped by water molecules. The prisms are connected by common edges forming bent chains [LaCl{sub 2}Cl{sub 4/2}(H{sub 2}O){sub 3}]{sub infinity}{sup -}. The three different coordination polyhedra around cesium are associated in three dimensions. The compounds with Ln = Ce, Pr, and Nd are isotypic. Upon heating these compounds to 130{degrees}C they decompose in one step to Cs{sub 3}LnCl{sub 6}. Cs{sub 3}LaCl{sub 6} and Cs{sub 3}CeCl{sub 6} crystallize into the Cs{sub 3}BiCl{sub 6} type. Cs{sub 3}PrCl{sub 6} and Cs{sub 3}NdCl{sub 6} belong to another type; its structure was determined from X-ray single-crystal data of Cs{sub 3}NdCl{sub 6} (space group Pbcm, a = 828.2(2) pm, b = 1322.5(4) pm, c = 2673.0(10) pm, Z = 8). The NdCl{sub 6} octahedra are slightly distorted, and the cesium cations are coordinated with 11 or 8 chlorine atoms. Using the notation of {open_quotes}layers of close-packed octahedra{close_quotes} the stacking frequency is compared with those of the Cs{sub 3}BiCl{sub 6}, K{sub 3}MoCl{sub 6}, and Rb{sub 3}BiBr{sub 6} types. When annealing the compounds for several days at 280{degrees}C they transform irreversibly into the Cs{sub 3}BiCl{sub 6} structure.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 146477
- Journal Information:
- Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 2 Vol. 116; ISSN 0022-4596; ISSN JSSCBI
- Country of Publication:
- United States
- Language:
- English
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