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Crystal structures of Ca(ClO4)2·4H2O and Ca(ClO4)2·6H2O.

Hennings E, Schmidt H, Voigt W - Acta Crystallogr Sect E Struct Rep Online (2014)

Bottom Line: The structure of the hexa-hydrate contains two different Ca(2+) cations, each coordinated by six water mol-ecules and two O atoms of two perchlorate tetra-hedra, forming [Ca(H2O)6(ClO4)]2 dimers by sharing two ClO4 tetra-hedra.The dimers are arranged in sheets parallel (001) and alternate with layers of non-coordinating ClO4 tetra-hedra.O-H⋯O hydrogen bonds between the water mol-ecules as donor and ClO4 tetra-hedra and water mol-ecules as acceptor groups lead to the formation of a three-dimensional network in the two structures.

View Article: PubMed Central - HTML - PubMed

Affiliation: TU Bergakademie Freiberg, Institute of Inorganic Chemistry, Leipziger Strasse 29, D-09596 Freiberg, Germany.

ABSTRACT
The title compounds, calcium perchlorate tetra-hydrate and calcium perchlorate hexa-hydrate, were crystallized at low temperatures according to the solid-liquid phase diagram. The structure of the tetra-hydrate consists of one Ca(2+) cation eightfold coordinated in a square-anti-prismatic fashion by four water mol-ecules and four O atoms of four perchlorate tetra-hedra, forming chains parallel to [01-1] by sharing corners of the ClO4 tetra-hedra. The structure of the hexa-hydrate contains two different Ca(2+) cations, each coordinated by six water mol-ecules and two O atoms of two perchlorate tetra-hedra, forming [Ca(H2O)6(ClO4)]2 dimers by sharing two ClO4 tetra-hedra. The dimers are arranged in sheets parallel (001) and alternate with layers of non-coordinating ClO4 tetra-hedra. O-H⋯O hydrogen bonds between the water mol-ecules as donor and ClO4 tetra-hedra and water mol-ecules as acceptor groups lead to the formation of a three-dimensional network in the two structures. Ca(ClO4)2·6H2O was refined as a two-component inversion twin, with an approximate twin component ratio of 1:1 in each of the two structures.

No MeSH data available.


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The principle building blocks in the structure of Ca(ClO4)2·6H2O. Displacement ellipsoids are drawn at the 50% probability level.
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fig2: The principle building blocks in the structure of Ca(ClO4)2·6H2O. Displacement ellipsoids are drawn at the 50% probability level.

Mentions: The two different Ca2+ cations in Ca(ClO4)·6H2O are each coordinated by six water mol­ecules and two perchlorate tetra­hedra (Fig. 2 ▶). Again, the bond lengths between the cations and water mol­ecules [2.319 (6)–2.500 (6) Å] are shorter than those to the perchlorate groups. For the latter, one of the two distances for each of the Ca2+ cations is by 0.5 Å markedly longer than the other (∼3.07 versus ∼2.53 Å). Nevertheless, according to the bond-valence model (Brown, 2002 ▶), the longer bond contributes ca. 0.05 valence units to the overall bond-valence sum and hence should not be neglected. If this longer bond is considered to be relevant, again a square anti-prismatic coordination polyhedron is realised for both Ca2+ cations, however with a much greater distortion. Two perchlorate tetra­hedra in the hexa­hydrate are shared between two Ca2+ ions, leading to the formation of [Ca(H2O)6(ClO4)]2 dimers oriented in layers parallel to (001).


Crystal structures of Ca(ClO4)2·4H2O and Ca(ClO4)2·6H2O.

Hennings E, Schmidt H, Voigt W - Acta Crystallogr Sect E Struct Rep Online (2014)

The principle building blocks in the structure of Ca(ClO4)2·6H2O. Displacement ellipsoids are drawn at the 50% probability level.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4257416&req=5

fig2: The principle building blocks in the structure of Ca(ClO4)2·6H2O. Displacement ellipsoids are drawn at the 50% probability level.
Mentions: The two different Ca2+ cations in Ca(ClO4)·6H2O are each coordinated by six water mol­ecules and two perchlorate tetra­hedra (Fig. 2 ▶). Again, the bond lengths between the cations and water mol­ecules [2.319 (6)–2.500 (6) Å] are shorter than those to the perchlorate groups. For the latter, one of the two distances for each of the Ca2+ cations is by 0.5 Å markedly longer than the other (∼3.07 versus ∼2.53 Å). Nevertheless, according to the bond-valence model (Brown, 2002 ▶), the longer bond contributes ca. 0.05 valence units to the overall bond-valence sum and hence should not be neglected. If this longer bond is considered to be relevant, again a square anti-prismatic coordination polyhedron is realised for both Ca2+ cations, however with a much greater distortion. Two perchlorate tetra­hedra in the hexa­hydrate are shared between two Ca2+ ions, leading to the formation of [Ca(H2O)6(ClO4)]2 dimers oriented in layers parallel to (001).

Bottom Line: The structure of the hexa-hydrate contains two different Ca(2+) cations, each coordinated by six water mol-ecules and two O atoms of two perchlorate tetra-hedra, forming [Ca(H2O)6(ClO4)]2 dimers by sharing two ClO4 tetra-hedra.The dimers are arranged in sheets parallel (001) and alternate with layers of non-coordinating ClO4 tetra-hedra.O-H⋯O hydrogen bonds between the water mol-ecules as donor and ClO4 tetra-hedra and water mol-ecules as acceptor groups lead to the formation of a three-dimensional network in the two structures.

View Article: PubMed Central - HTML - PubMed

Affiliation: TU Bergakademie Freiberg, Institute of Inorganic Chemistry, Leipziger Strasse 29, D-09596 Freiberg, Germany.

ABSTRACT
The title compounds, calcium perchlorate tetra-hydrate and calcium perchlorate hexa-hydrate, were crystallized at low temperatures according to the solid-liquid phase diagram. The structure of the tetra-hydrate consists of one Ca(2+) cation eightfold coordinated in a square-anti-prismatic fashion by four water mol-ecules and four O atoms of four perchlorate tetra-hedra, forming chains parallel to [01-1] by sharing corners of the ClO4 tetra-hedra. The structure of the hexa-hydrate contains two different Ca(2+) cations, each coordinated by six water mol-ecules and two O atoms of two perchlorate tetra-hedra, forming [Ca(H2O)6(ClO4)]2 dimers by sharing two ClO4 tetra-hedra. The dimers are arranged in sheets parallel (001) and alternate with layers of non-coordinating ClO4 tetra-hedra. O-H⋯O hydrogen bonds between the water mol-ecules as donor and ClO4 tetra-hedra and water mol-ecules as acceptor groups lead to the formation of a three-dimensional network in the two structures. Ca(ClO4)2·6H2O was refined as a two-component inversion twin, with an approximate twin component ratio of 1:1 in each of the two structures.

No MeSH data available.


Related in: MedlinePlus