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Crystal structure of tetra-wickmanite, Mn(2+)Sn(4+)(OH)6.

Lafuente B, Yang H, Downs RT - Acta Crystallogr E Crystallogr Commun (2015)

Bottom Line: The vacant A site is in a cavity in the centre of a distorted cube formed by eight octa-hedra at the corners.However, the hydrogen-atom positions and their hydrogen bonds are not equivalent in every cavity, resulting in two distinct environments.One of the cavities contains a ring of four hydrogen bonds, similar to that found in wickmanite, while the other cavity is more distorted and forms crankshaft-type chains of hydrogen bonds, as previously proposed for tetra-gonal stottite, Fe(2+)Ge(4+)(OH)6.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Geosciences, University of Arizona, 1040 E. 4th Street, Tucson, AZ 85721-0077, USA.

ABSTRACT
The crystal structure of tetra-wickmanite, ideally Mn(2+)Sn(4+)(OH)6 [mangan-ese(II) tin(IV) hexa-hydroxide], has been determined based on single-crystal X-ray diffraction data collected from a natural sample from Långban, Sweden. Tetra-wickmanite belongs to the octa-hedral-framework group of hydroxide-perovskite minerals, described by the general formula BB'(OH)6 with a perovskite derivative structure. The structure differs from that of an ABO3 perovskite in that the A site is empty while each O atom is bonded to an H atom. The perovskite B-type cations split into ordered B and B' sites, which are occupied by Mn(2+) and Sn(4+), respectively. Tetra-wickmanite exhibits tetra-gonal symmetry and is topologically similar to its cubic polymorph, wickmanite. The tetra-wickmanite structure is characterized by a framework of alternating corner-linked [Mn(2+)(OH)6] and [Sn(4+)(OH)6] octa-hedra, both with point-group symmetry -1. Four of the five distinct H atoms in the structure are statistically disordered. The vacant A site is in a cavity in the centre of a distorted cube formed by eight octa-hedra at the corners. However, the hydrogen-atom positions and their hydrogen bonds are not equivalent in every cavity, resulting in two distinct environments. One of the cavities contains a ring of four hydrogen bonds, similar to that found in wickmanite, while the other cavity is more distorted and forms crankshaft-type chains of hydrogen bonds, as previously proposed for tetra-gonal stottite, Fe(2+)Ge(4+)(OH)6.

No MeSH data available.


Related in: MedlinePlus

The crystal structure of tetra­wickmanite showing atoms with anisotropic displacement ellipsoids at the 99% probability level. Yellow, grey and red ellipsoids represent Mn, Sn and O atoms, respectively. Blue spheres of arbitrary radius represent H atoms.
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fig2: The crystal structure of tetra­wickmanite showing atoms with anisotropic displacement ellipsoids at the 99% probability level. Yellow, grey and red ellipsoids represent Mn, Sn and O atoms, respectively. Blue spheres of arbitrary radius represent H atoms.

Mentions: The structure of tetra­wickmanite is characterized by a framework of alternating corner-linked [Mn2+(OH)6] and [Sn4+(OH)6] octa­hedra, centred at special positions 4d and 4c, respectively (site symmetry ) (Fig. 1 ▸b). The Mn—O distances are 2.2007 (13), 2.1933 (12) and 2.2009 (14) Å (average 2.198 Å) and the Sn—O distances are 2.0654 (13), 2.0523 (12) and 2.0446 (13) Å (average 2.054 Å), both similar to the inter­atomic distances determined from neutron powder diffraction data for synthetic wickmanite (Mn—O average 2.181 Å and Sn—O average 2.055 Å; Basciano et al., 1998 ▸). The tetra­wickmanite structure contains three non-equivalent O atoms, all protonated as OH groups and located at general positions. H1, H2, H3 and H4 are statistically disordered within the structure while H5 is ordered (Fig. 2 ▸).


Crystal structure of tetra-wickmanite, Mn(2+)Sn(4+)(OH)6.

Lafuente B, Yang H, Downs RT - Acta Crystallogr E Crystallogr Commun (2015)

The crystal structure of tetra­wickmanite showing atoms with anisotropic displacement ellipsoids at the 99% probability level. Yellow, grey and red ellipsoids represent Mn, Sn and O atoms, respectively. Blue spheres of arbitrary radius represent H atoms.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4384573&req=5

fig2: The crystal structure of tetra­wickmanite showing atoms with anisotropic displacement ellipsoids at the 99% probability level. Yellow, grey and red ellipsoids represent Mn, Sn and O atoms, respectively. Blue spheres of arbitrary radius represent H atoms.
Mentions: The structure of tetra­wickmanite is characterized by a framework of alternating corner-linked [Mn2+(OH)6] and [Sn4+(OH)6] octa­hedra, centred at special positions 4d and 4c, respectively (site symmetry ) (Fig. 1 ▸b). The Mn—O distances are 2.2007 (13), 2.1933 (12) and 2.2009 (14) Å (average 2.198 Å) and the Sn—O distances are 2.0654 (13), 2.0523 (12) and 2.0446 (13) Å (average 2.054 Å), both similar to the inter­atomic distances determined from neutron powder diffraction data for synthetic wickmanite (Mn—O average 2.181 Å and Sn—O average 2.055 Å; Basciano et al., 1998 ▸). The tetra­wickmanite structure contains three non-equivalent O atoms, all protonated as OH groups and located at general positions. H1, H2, H3 and H4 are statistically disordered within the structure while H5 is ordered (Fig. 2 ▸).

Bottom Line: The vacant A site is in a cavity in the centre of a distorted cube formed by eight octa-hedra at the corners.However, the hydrogen-atom positions and their hydrogen bonds are not equivalent in every cavity, resulting in two distinct environments.One of the cavities contains a ring of four hydrogen bonds, similar to that found in wickmanite, while the other cavity is more distorted and forms crankshaft-type chains of hydrogen bonds, as previously proposed for tetra-gonal stottite, Fe(2+)Ge(4+)(OH)6.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Geosciences, University of Arizona, 1040 E. 4th Street, Tucson, AZ 85721-0077, USA.

ABSTRACT
The crystal structure of tetra-wickmanite, ideally Mn(2+)Sn(4+)(OH)6 [mangan-ese(II) tin(IV) hexa-hydroxide], has been determined based on single-crystal X-ray diffraction data collected from a natural sample from Långban, Sweden. Tetra-wickmanite belongs to the octa-hedral-framework group of hydroxide-perovskite minerals, described by the general formula BB'(OH)6 with a perovskite derivative structure. The structure differs from that of an ABO3 perovskite in that the A site is empty while each O atom is bonded to an H atom. The perovskite B-type cations split into ordered B and B' sites, which are occupied by Mn(2+) and Sn(4+), respectively. Tetra-wickmanite exhibits tetra-gonal symmetry and is topologically similar to its cubic polymorph, wickmanite. The tetra-wickmanite structure is characterized by a framework of alternating corner-linked [Mn(2+)(OH)6] and [Sn(4+)(OH)6] octa-hedra, both with point-group symmetry -1. Four of the five distinct H atoms in the structure are statistically disordered. The vacant A site is in a cavity in the centre of a distorted cube formed by eight octa-hedra at the corners. However, the hydrogen-atom positions and their hydrogen bonds are not equivalent in every cavity, resulting in two distinct environments. One of the cavities contains a ring of four hydrogen bonds, similar to that found in wickmanite, while the other cavity is more distorted and forms crankshaft-type chains of hydrogen bonds, as previously proposed for tetra-gonal stottite, Fe(2+)Ge(4+)(OH)6.

No MeSH data available.


Related in: MedlinePlus