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'Pd20Sn13' revisited: crystal structure of Pd6.69Sn4.31.

Klein W, Jin H, Hlukhyy V, Fässler TF - Acta Crystallogr E Crystallogr Commun (2015)

Bottom Line: The crystal structure can be derived from the AlB2 type of structure after removing one eighth of the atoms at the boron positions and shifting adjacent atoms in the same layer in the direction of the voids.One atomic site is partially occupied by both elements with a Pd:Sn ratio of 0.38 (3):0.62 (3).One Sn and three Pd atoms are located on special positions with site symmetry 2. (Wyckoff letter 3a and 3b).

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Affiliation: Technische Universität München, Department of Chemistry, Lichtenbergstrasse 4, 85747 Garching, Germany.

ABSTRACT
The crystal structure of the title compound was previously reported with composition 'Pd20Sn13' [Sarah et al. (1981 ▸). Z. Metallkd, 72, 517-520]. For the original structure model, as determined from powder X-ray data, atomic coordinates from the isostructural compound Ni13Ga3Ge6 were transferred. The present structure determination, resulting in a composition Pd6.69Sn4.31, is based on single crystal X-ray data and includes anisotropic displacement parameters for all atoms as well as standard uncertainties for the atomic coordinates, leading to higher precision and accuracy for the structure model. Single crystals of the title compound were obtained via a solid-state reaction route, starting from the elements. The crystal structure can be derived from the AlB2 type of structure after removing one eighth of the atoms at the boron positions and shifting adjacent atoms in the same layer in the direction of the voids. One atomic site is partially occupied by both elements with a Pd:Sn ratio of 0.38 (3):0.62 (3). One Sn and three Pd atoms are located on special positions with site symmetry 2. (Wyckoff letter 3a and 3b).

No MeSH data available.


Sections of the crystal structure of Pd6.69Sn4.31, with a) layers ‘B1’–‘Al1’–‘B6’ and b) layers ‘B2’–‘Al2’–‘B1’. The voids are drawn as empty squares and are connected to the neighbouring Sn atoms by dashed lines. Shown are the surroundings of the ‘B’ layer atoms with zero (Sn1), one (Pd4) and two voids (Pd1, Pd2, Pd3, Pd5). Anisotropic displacement ellipsoids are drawn at the 90% probability level.
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fig3: Sections of the crystal structure of Pd6.69Sn4.31, with a) layers ‘B1’–‘Al1’–‘B6’ and b) layers ‘B2’–‘Al2’–‘B1’. The voids are drawn as empty squares and are connected to the neighbouring Sn atoms by dashed lines. Shown are the surroundings of the ‘B’ layer atoms with zero (Sn1), one (Pd4) and two voids (Pd1, Pd2, Pd3, Pd5). Anisotropic displacement ellipsoids are drawn at the 90% probability level.

Mentions: For Sn1 a partial occupation by Pd (Pd9) was found. A full occupation of the (Sn1/Pd9) site (Fig. 3 ▸a) by the element Sn would result in the composition Pd13Sn9 as suggested by the isostructural compound Ni13Ga3Ge6. However, the occupancy of this position (in contrast to all other Pd and Sn sites) deviates significantly from 100% if only Sn (refined to 96%) or Pd (refined to 107%) is considered. It has to be noticed that this site is the only one in both kinds of ‘Al’ layers that is not close to a void in the ‘B’ layers (Fig. 3 ▸). Consequently, the coordination number (CN) of the (Sn1/Pd9) site is 14, which is higher than that of all other Sn (CN = 10) and Pd atoms (CN = 11–13) in Pd6.69Sn4.31.


'Pd20Sn13' revisited: crystal structure of Pd6.69Sn4.31.

Klein W, Jin H, Hlukhyy V, Fässler TF - Acta Crystallogr E Crystallogr Commun (2015)

Sections of the crystal structure of Pd6.69Sn4.31, with a) layers ‘B1’–‘Al1’–‘B6’ and b) layers ‘B2’–‘Al2’–‘B1’. The voids are drawn as empty squares and are connected to the neighbouring Sn atoms by dashed lines. Shown are the surroundings of the ‘B’ layer atoms with zero (Sn1), one (Pd4) and two voids (Pd1, Pd2, Pd3, Pd5). Anisotropic displacement ellipsoids are drawn at the 90% probability level.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4518917&req=5

fig3: Sections of the crystal structure of Pd6.69Sn4.31, with a) layers ‘B1’–‘Al1’–‘B6’ and b) layers ‘B2’–‘Al2’–‘B1’. The voids are drawn as empty squares and are connected to the neighbouring Sn atoms by dashed lines. Shown are the surroundings of the ‘B’ layer atoms with zero (Sn1), one (Pd4) and two voids (Pd1, Pd2, Pd3, Pd5). Anisotropic displacement ellipsoids are drawn at the 90% probability level.
Mentions: For Sn1 a partial occupation by Pd (Pd9) was found. A full occupation of the (Sn1/Pd9) site (Fig. 3 ▸a) by the element Sn would result in the composition Pd13Sn9 as suggested by the isostructural compound Ni13Ga3Ge6. However, the occupancy of this position (in contrast to all other Pd and Sn sites) deviates significantly from 100% if only Sn (refined to 96%) or Pd (refined to 107%) is considered. It has to be noticed that this site is the only one in both kinds of ‘Al’ layers that is not close to a void in the ‘B’ layers (Fig. 3 ▸). Consequently, the coordination number (CN) of the (Sn1/Pd9) site is 14, which is higher than that of all other Sn (CN = 10) and Pd atoms (CN = 11–13) in Pd6.69Sn4.31.

Bottom Line: The crystal structure can be derived from the AlB2 type of structure after removing one eighth of the atoms at the boron positions and shifting adjacent atoms in the same layer in the direction of the voids.One atomic site is partially occupied by both elements with a Pd:Sn ratio of 0.38 (3):0.62 (3).One Sn and three Pd atoms are located on special positions with site symmetry 2. (Wyckoff letter 3a and 3b).

View Article: PubMed Central - HTML - PubMed

Affiliation: Technische Universität München, Department of Chemistry, Lichtenbergstrasse 4, 85747 Garching, Germany.

ABSTRACT
The crystal structure of the title compound was previously reported with composition 'Pd20Sn13' [Sarah et al. (1981 ▸). Z. Metallkd, 72, 517-520]. For the original structure model, as determined from powder X-ray data, atomic coordinates from the isostructural compound Ni13Ga3Ge6 were transferred. The present structure determination, resulting in a composition Pd6.69Sn4.31, is based on single crystal X-ray data and includes anisotropic displacement parameters for all atoms as well as standard uncertainties for the atomic coordinates, leading to higher precision and accuracy for the structure model. Single crystals of the title compound were obtained via a solid-state reaction route, starting from the elements. The crystal structure can be derived from the AlB2 type of structure after removing one eighth of the atoms at the boron positions and shifting adjacent atoms in the same layer in the direction of the voids. One atomic site is partially occupied by both elements with a Pd:Sn ratio of 0.38 (3):0.62 (3). One Sn and three Pd atoms are located on special positions with site symmetry 2. (Wyckoff letter 3a and 3b).

No MeSH data available.