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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

Cavity (left) and hydrogen-bonding linkages (right) in tetra­wickmanite. (a) Wickmanite-like cavity with isolated four-membered ring motif O3—H5⋯O3 and linkages O1—H1⋯O1 at the top and bottom of the cavity. (b) Sets of <100> crankshaft-type motifs with the isolated four-membered rings lining in the plane perpendicular to the c axis. Yellow, grey and red spheres represent Mn, Sn and O atoms. Blue, purple, pink, aqua­marine and orange spheres represent H1, H2, H3, H4 and H5 hydrogen atoms, respectively.
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fig3: Cavity (left) and hydrogen-bonding linkages (right) in tetra­wickmanite. (a) Wickmanite-like cavity with isolated four-membered ring motif O3—H5⋯O3 and linkages O1—H1⋯O1 at the top and bottom of the cavity. (b) Sets of <100> crankshaft-type motifs with the isolated four-membered rings lining in the plane perpendicular to the c axis. Yellow, grey and red spheres represent Mn, Sn and O atoms. Blue, purple, pink, aqua­marine and orange spheres represent H1, H2, H3, H4 and H5 hydrogen atoms, respectively.

Mentions: Wickmanite has a single type of cavity with the H atom disordered over two positions, forming a ring of four hydrogen-bonds with two other hydrogen-bonds at the top and the bottom of the cavity (Basciano et al., 1998 ▸). However, in tetra­wickmanite, the hydrogen positions and their hydrogen bonds (Table 1 ▸) are not equivalent in every cavity, and exhibit two distinct environments. One of the cavities is similar to that of wickmanite, with isolated four-membered hydrogen-bonding ring motifs defined by O3—H5⋯O3 [2.752 (2) Å] and linkages O1—H1⋯O1 [3.047 (3) Å] at the top and bottom of the cavity (Fig. 3 ▸a). In tetra­wickmanite, the four-membered ring has equal O3⋯O3 distances [2.752 (2) Å] while in wickmanite, the O⋯O distances alternate between 2.928 and 2.752 Å. Presumably, the shorter O⋯O distances within the ring motif in tetra­wickmanite is correlated with the ordering of the H5 atom.


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

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

Cavity (left) and hydrogen-bonding linkages (right) in tetra­wickmanite. (a) Wickmanite-like cavity with isolated four-membered ring motif O3—H5⋯O3 and linkages O1—H1⋯O1 at the top and bottom of the cavity. (b) Sets of <100> crankshaft-type motifs with the isolated four-membered rings lining in the plane perpendicular to the c axis. Yellow, grey and red spheres represent Mn, Sn and O atoms. Blue, purple, pink, aqua­marine and orange spheres represent H1, H2, H3, H4 and H5 hydrogen atoms, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4384573&req=5

fig3: Cavity (left) and hydrogen-bonding linkages (right) in tetra­wickmanite. (a) Wickmanite-like cavity with isolated four-membered ring motif O3—H5⋯O3 and linkages O1—H1⋯O1 at the top and bottom of the cavity. (b) Sets of <100> crankshaft-type motifs with the isolated four-membered rings lining in the plane perpendicular to the c axis. Yellow, grey and red spheres represent Mn, Sn and O atoms. Blue, purple, pink, aqua­marine and orange spheres represent H1, H2, H3, H4 and H5 hydrogen atoms, respectively.
Mentions: Wickmanite has a single type of cavity with the H atom disordered over two positions, forming a ring of four hydrogen-bonds with two other hydrogen-bonds at the top and the bottom of the cavity (Basciano et al., 1998 ▸). However, in tetra­wickmanite, the hydrogen positions and their hydrogen bonds (Table 1 ▸) are not equivalent in every cavity, and exhibit two distinct environments. One of the cavities is similar to that of wickmanite, with isolated four-membered hydrogen-bonding ring motifs defined by O3—H5⋯O3 [2.752 (2) Å] and linkages O1—H1⋯O1 [3.047 (3) Å] at the top and bottom of the cavity (Fig. 3 ▸a). In tetra­wickmanite, the four-membered ring has equal O3⋯O3 distances [2.752 (2) Å] while in wickmanite, the O⋯O distances alternate between 2.928 and 2.752 Å. Presumably, the shorter O⋯O distances within the ring motif in tetra­wickmanite is correlated with the ordering of the H5 atom.

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