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Syntheses and Crystal Structures of Hydrated Ternary Cerium Sulfates: Mixed‐valence K 5 Ce 2 (SO 4 ) 6 ·H 2 O and K 2 Ce(SO 4 ) 3 ·H 2 O
Author(s) -
Casari Barbara M.,
Langer Vratislav
Publication year - 2007
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200600381
Subject(s) - crystallography , cerium , chemistry , delocalized electron , dimer , crystal structure , valence (chemistry) , ion , molecule , ternary operation , hydrogen bond , inorganic chemistry , computer science , programming language , organic chemistry
A new chemical and structural interpretation of K 5 Ce 2 (SO 4 ) 6 ·H 2 O ( I ) and a redetermination of the structure of K 2 Ce(SO 4 ) 3 ·H 2 O ( II ) is presented. The mixed‐valent compound I crystallizes in the space group C 2 /c with a = 17.7321(3), b = 7.0599(1), c = 19.4628(4) Å, β = 112.373(1)° and Z = 4. Compound I has been discussed earlier with space group Cc . In the structure of I , there are pairs of edge sharing cerium polyhedra connected by sulfate oxygen atoms in the μ 3 bonding mode. These cerium dimers are linked through edge and corner sharing sulfate bridges, forming layers. The layers are joined by potassium ions which together with the water molecules are placed between the layers. No irregularity in the distribution of the Ce III and Ce IV to cause the lost of a crystallographic center of symmetry was detected. We suggest that the charge exerted by the extra f 1 electron for every cerium dimer is delocalized over the Ce1–O 2 –Ce2 moiety in a non‐bonding mode. As a result, the oxidations state of each cerium ion is a mean value between III and IV at each atomic position. Compound II crystallizes in the space group C 2 with a = 20.6149(2), b = 7.0742(1), c = 17.8570(1) Å, β = 122.720(1)° and Z = 8. The hydrogen atoms have been located and the absolute structure has been established. Neither hydrogen atom positions nor anisotropic displacement parameters were given in the previous reports. In compound II , the cerium polyhedra are connected by edge and corner sharing sulfate groups forming a three‐dimensional network. This network contains Z‐shaped channels hosting the charge compensating potassium ions.