inorganic compounds
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The title compound, lithium/sodium iron(III) bis[orthomolybdate(VI)], was obtained by a solid-state reaction. The main structure units are an FeO6 octahedron, a distorted MoO6 octahedron and an MoO4 tetrahedron sharing corners. The crystal structure is composed of infinite double MoFeO11 chains along the b-axis direction linked by corner-sharing to MoO4 tetrahedra so as to form Fe2Mo3O19 ribbons. The cohesion between ribbons via mixed Mo—O—Fe bridges leads to layers arranged parallel to the bc plane. Adjacent layers are linked by corners shared between MoO4 tetrahedra of one layer and FeO6 octahedra of the other layer. The Na+ and Li+ ions partially occupy the same general position, with a site-occupancy ratio of 0.631 (9):0.369 (1). A comparison is made with AFe(MoO4)2 (A = Li, Na, K and Cs) structures.
inorganic compounds
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The title compound, disodium dimanganese(II) tris[orthomolybdate(VI)], was prepared by solid-state reactions. The structure can be described as being composed of Mn2Mo2O14 double-chains that are interconnected by corner-sharing with MoO4 tetrahedra, leading to a three-dimensional framework with channels propagating in [100] and [001] in which the Na+ counter-cations are located. One of these Na sites is located on an inversion centre, one is partially occupied [occupancy 0.341 (9)], and one is statistically occupied by Na and Mn in a ratio of 0.829 (5):0.171 (5). Na1.67Mn2.17(MoO4)3 is isotypic with structures of the Ag2M2(MoO4)3 (M = Zn, Mg, Co, Mn) family. A comparative structural description is provided between the structure of the title compound and those of related phases containing (MXO8)n chains (M = Mo, Mn and X = As) or M2O10 (M = Mo, Mn, Nb, V) dimers.
inorganic compounds
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The title compound, nonaniobium vanadium pentacosaoxide, was prepared by a solid-state reaction at 1198 K. It is isotypic with Nb9AsO25, Nb9PO25 and Ta9VO25. The structure consists of NbO6 octahedra (one with 4/m.. and two with m.. symmetry) and VO4 tetrahedra (-4.. symmetry) sharing corners and edges to form a three-dimensional framework. This framework can be considered as a junction between ribbons made up from NbO6 octahedra and chains of NbO6 octahedra and chains of VO4 tetrahedra. The V site shows half-occupancy, hence one half of the VO4 tetrahedra is unoccupied. The structural differences with α-Nb9VO25, VOSO4, SbOPO4 and NbOPO4 oxides are discussed.
inorganic compounds
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The title compound α-ammonium iron(III) bis[hydrogen arsenate(V)], α-NH4Fe(HAsO4)2 (or poly[ammonium bis(μ-hydrogen arsenato)ferrate(III)], {NH4[Fe(HAsO4)2]}n), synthesized hydrothermally, is isostructural with NH4Fe(HPO4)2. Condensation of the hydrogen arsenate groups with FeO6 coordination octahedra via common corners results in an overall three-dimensional framework containing interconnected channels parallel to the a-, b- and c-axis directions. The NH4+ cations are located in three intersecting tunnels, which is promising as an ion exchange. Hydrogen bonding of the types O—HO and N—HO consolidates the packing of the structure. The distortion of the coordination polyhedra is analyzed by means of the effective coordination number and distortion indices. Structural relationships with other compounds of general formula MIMIII[HXO4)]2 (X = P, As) are discussed.
inorganic compounds
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The title compound, dirubidium dimanganese(II) tris(tetraoxomolybdate), Rb2Mn2(MoO4)3, was prepared by solid-state reactions. The structure can be described as being composed of MnO6 octahedra sharing corners with MoO4 tetrahedra. The three-dimensional framework contains cavities in which the rubidium ions are located. The Rb+ cations are within distorted nine- and 12-vertex polyhedra. The pairs of different Mn2+ and Rb+ cations are each located on threefold rotation axes.. Rb2Mn2(MoO4)3 is isotypic with compounds of the Cs2M2Mo3O12 (M = Ni, Fe) family. A comparative structural description is provided between the structure of the title compound and those of related phases. Differences with structures such as alluaudite are discussed.
inorganic compounds
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The title compound, tripotassium iron(III) bis(orthomolybdate) dimolybdate, was obtained by a solid-state reaction. The main structural building units are one FeO6 octahedron, two MoO4 tetrahedra and one Mo2O7 dimolybdate group, all with point group symmetries m. These units are linked via corner-sharing to form ribbons parallel to [010]. The three K+ cations are located between the ribbons on mirror planes and have coordination numbers of 10 and 12. Two O atoms of one of the MoO4 tetrahedra of the dimolybdate group are disordered over two positions in a 0.524 (11):0.476 (11) ratio. The structure of the title compound is compared briefly with that of Rb3FeMo4O15.