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Redetermination of metarossite, CaV 5+ 2 O 6 · 2H 2 O

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ABSTRACT

6: The crystal structure of metarossite, ideally CaV2O6·2H2O [chemical name: calcium divanadium(V) hexa­oxide dihydrate], was first determined using precession photographs, with fixed isotropic displacement parameters and without locating the positions of the H atoms, leading to a reliability factor R = 0.11 [Kelsey & Barnes (1960 ▸). Can. Mineral., 448–466]. This communication reports a structure redetermination of this mineral on the basis of single-crystal X-ray diffraction data of a natural sample from the Blue Cap mine, San Juan County, Utah, USA (R1 = 0.036). Our study not only confirms the structural topology reported in the previous study, but also makes possible the refinement of all non-H atoms with anisotropic displacement parameters and all H atoms located. The metarossite structure is characterized by chains of edge-sharing [CaO8] polyhedra parallel to [100] that are themselves connected by chains of alternating [VO5] trigonal bipyramids parallel to [010]. The two H2O mol­ecules are bonded to Ca. Analysis of the displacement parameters show that the [VO5] chains librate around [010]. In addition, we measured the Raman spectrum of metarossite and compared it with IR and Raman data previously reported. Moreover, heating of metarossite led to a loss of water, which results in a transformation to the brannerite-type structure, CaV2O6, implying a possible dehydration pathway for the compounds M2+V2O6·xH2O, with M = Cu, Cd, Mg or Mn, and x = 2 or 4.

No MeSH data available.


Crystal structure of metarossite, showing (a) the chains of alternating [V1O5] and [V2O5] trigonal bipyramids (yellow and green, respectively) along [010], and (b) the chains of edge-sharing distorted [CaO8] square anti­prisms (magenta) along [100]. H atoms are represented by blue spheres; hydrogen bonding is indicated by dashed lines.
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fig2: Crystal structure of metarossite, showing (a) the chains of alternating [V1O5] and [V2O5] trigonal bipyramids (yellow and green, respectively) along [010], and (b) the chains of edge-sharing distorted [CaO8] square anti­prisms (magenta) along [100]. H atoms are represented by blue spheres; hydrogen bonding is indicated by dashed lines.

Mentions: The structural topology of metarossite for all non-hydrogen atoms from this study is identical to that reported by Kelsey & Barnes (1960 ▸). Chains of edge-sharing distorted [VO5] trigonal bipyramids run parallel to [010], with [V1O5] and [V2O5] polyhedra alternating along the chains (Fig. 2 ▸a). These chains are linked by chains of edge-sharing [CaO8] polyhedra aligned parallel to [100] (Fig. 2 ▸b). The water mol­ecules are located at three vertices of the [CaO8] polyhedra [OW3, OW8i and OW8ii; symmetry codes: (i) −x + 1, −y + 1, −z; (ii) x + 1, y, z].


Redetermination of metarossite, CaV 5+ 2 O 6 · 2H 2 O
Crystal structure of metarossite, showing (a) the chains of alternating [V1O5] and [V2O5] trigonal bipyramids (yellow and green, respectively) along [010], and (b) the chains of edge-sharing distorted [CaO8] square anti­prisms (magenta) along [100]. H atoms are represented by blue spheres; hydrogen bonding is indicated by dashed lines.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC5120707&req=5

fig2: Crystal structure of metarossite, showing (a) the chains of alternating [V1O5] and [V2O5] trigonal bipyramids (yellow and green, respectively) along [010], and (b) the chains of edge-sharing distorted [CaO8] square anti­prisms (magenta) along [100]. H atoms are represented by blue spheres; hydrogen bonding is indicated by dashed lines.
Mentions: The structural topology of metarossite for all non-hydrogen atoms from this study is identical to that reported by Kelsey & Barnes (1960 ▸). Chains of edge-sharing distorted [VO5] trigonal bipyramids run parallel to [010], with [V1O5] and [V2O5] polyhedra alternating along the chains (Fig. 2 ▸a). These chains are linked by chains of edge-sharing [CaO8] polyhedra aligned parallel to [100] (Fig. 2 ▸b). The water mol­ecules are located at three vertices of the [CaO8] polyhedra [OW3, OW8i and OW8ii; symmetry codes: (i) −x + 1, −y + 1, −z; (ii) x + 1, y, z].

View Article: PubMed Central - HTML - PubMed

ABSTRACT

6: The crystal structure of metarossite, ideally CaV2O6·2H2O [chemical name: calcium divanadium(V) hexa­oxide dihydrate], was first determined using precession photographs, with fixed isotropic displacement parameters and without locating the positions of the H atoms, leading to a reliability factor R = 0.11 [Kelsey & Barnes (1960 ▸). Can. Mineral., 448–466]. This communication reports a structure redetermination of this mineral on the basis of single-crystal X-ray diffraction data of a natural sample from the Blue Cap mine, San Juan County, Utah, USA (R1 = 0.036). Our study not only confirms the structural topology reported in the previous study, but also makes possible the refinement of all non-H atoms with anisotropic displacement parameters and all H atoms located. The metarossite structure is characterized by chains of edge-sharing [CaO8] polyhedra parallel to [100] that are themselves connected by chains of alternating [VO5] trigonal bipyramids parallel to [010]. The two H2O mol­ecules are bonded to Ca. Analysis of the displacement parameters show that the [VO5] chains librate around [010]. In addition, we measured the Raman spectrum of metarossite and compared it with IR and Raman data previously reported. Moreover, heating of metarossite led to a loss of water, which results in a transformation to the brannerite-type structure, CaV2O6, implying a possible dehydration pathway for the compounds M2+V2O6·xH2O, with M = Cu, Cd, Mg or Mn, and x = 2 or 4.

No MeSH data available.