Structure and magnetism of the quasi-1-d K4Cu(MoO4)3 and the structure of K4Zn(MoO4)3

Single crystals of K(4)Cu(MoO(4))(3) and nonmagnetic K(4)Zn(MoO(4))(3) have been grown by the flux-growth method. K(4)Cu(MoO(4))(3) can be described as a quantum quasi-1-d antiferromagnet with correlations between neighboring Cu(2+) ions but no magnetic long-range ordering down to 0.4 K. Comparison of the structure and magnetic properties of isostructural A(4)Cu(MoO(4))(3) (A = K, Rb) allows the isolation of the effects of low dimensionality from structural distortion along the Cu-O-Mo chains. The characteristic one-dimensional behavior is hence suppressed to lower the temperature in K(4)Cu(MoO(4))(3) in comparison with that of the Rb analogue. For example, a broad peak in the specific heat is observed ~2.3 K at 0 T, which is consistent with the onset of the quantum spin liquid state.     

New triple molybdates Cs3LiCo2(MoO4)4 and Rb3LiZn2(MoO4)4, filled derivatives of the Cs6Zn5(MoO4)8 type

Two new isotypic triple molybdates, namely tri­cesium lithium dicobalt tetra­kis­(tetra­oxo­molybdate), Cs₃LiCo₂(MoO₄)₄, and tri­rubidium lithium dizinc tetra­kis­(tetra­oxo­molybdate), Rb₃LiZn₂(MoO₄)₄, crystallize in the non‐centrosymmetric cubic space group I3d and adopt the Cs₆Zn₅(MoO₄)₈ structure type. In the parent structure, the Zn positions have 5/6 occupancy, while they are fully occupied by statistically distributed M²⁺ and Li⁺ cations in the title compounds. In both structures, all corners of the (M_2/3Li_1/3)O₄ tetra­hedra (M = Co and Zn), having point symmetry , are shared with the MoO₄ tetra­hedra, which lie on threefold axes and share corners with three (M,Li)O₄ tetra­hedra to form open mixed frameworks. Large alkaline cations occupy distorted cubocta­hedral cavities with symmetry. The mixed tetra­hedral frameworks in the structures are close to those of mayenite (12CaO·7Al₂O₃) and the related compounds 11CaO·7Al₂O₃·CaF₂, wadalite (Ca₆Al₅Si₂O₁₆Cl₃) and Na₆Zn₃(AsO₄)₄·3H₂O, but the terminal vertices of the MoO₄ tetra­hedra are directed in opposite directions along the threefold axes compared with the configurations of Al(Si)O₄ or AsO₄ tetra­hedra. The cation arrangements in Cs₃LiCo₂(MoO₄)₄, Rb₃LiZn₂(MoO₄)₄ and Cs₆Zn₅(MoO₄)₈ repeat the structure of Y₃Au₃Sb₄, being stuffed derivatives of the Th₃P₄ type.     

Structure of BaGd2（MoO4）4 Crystal

The title compound belongs to monoclinic,space group C2/c with a=5.2694(1),b=12.6659(4),c=19.4108(2) ,β=91.504(2)°,V=1295.06(5) 3,Z=4 and Dc=5.599 g/cm3. The structure of BaGd2(MoO4)4 contains a MoO4 tetrahedron,a distorted GdO8 polyhedron,and Ba2+ ions in a tenfold coordination. The GdO8 polyhedra are linked together through edge-sharing to give a two-dimensional Gd layer. The MoO4 tetrahedra connected to the Gd atoms are capped up and down the Gd layer through common oxygen apices,thus forming a new Gd-Mo layer. Finally,the Gd-Mo layers are held together through bridging BaO10 polyhedra to form a three-dimensional framework. Since the Ba-μ3-O bond has a large average distance of 2.888 ,this structural characteristic will result in a cleavage along the (001) plane.     

Systems Tl2MoO4-E(MoO4)2, where E = Zr or Hf, and the crystal structure of Tl8Hf(MoO4)6

Systems Tl₂MoO₄-E(MoO₄)₂ (E = Zr, Hf) are studied using X-ray powder diffraction, DTA, and IR spectroscopy. Compounds Tl₈E(MoO₄)₆ and Tl₂E(MoO₄)₂ are found in these systems. T-x diagrams for the Tl₂MoO₄-Zr(MoO₄)₂ system are designed. Single crystals are grown and structure is solved for Tl₈Hf(MoO₄)₆. The compound crystallizes in a monoclinic structure with the unit cell parameters a = 9.9688(6) Å, b = 18.830(1) Å, c = 7.8488(5) Å, β = 108.538(1)°, Z = 2, space group C2/m. The main structural fragment is a [HfMo₆O₂₄]^8? isle group. Three crystallographically independent types of Tl polyhedra uniformly fill spaces between [HfMo₆O₂₄]^8? fragments to form a three-dimensional framework.     

LiFe(MoO4)2, LiGa(MoO4)2 and Li3Ga(MoO4)3

The structures of lithium iron dimolybdate, LiFe(MoO₄)₂, and lithium gallium dimolybdate, LiGa(MoO₄)₂, are shown to be isomorphous with each other. Their structures consist of segregated layers of LiO₆ bicapped trigonal bipyramids and Fe(Ga)O₆ octahedra separated and linked by layers of isolated MoO₄ tetrahedra. The redetermined structure of trilithium gallium trimolybdate, Li₃Ga(MoO₄)₃, shows substitional disorder on the Li/Ga site and consists of perpendicular chains of LiO₆ trigonal prisms and two types of differently linked Li/GaO₆ octahedra.     

ChemInform Abstract: From 1∞ [(UO2)2O(MoO4)4]6‐ to 1∞ [(UO2)2(MoO4)3(MoO5)] 6‐ Infinite Chains in A6U2Mo4O21 (A: Na,K, Rb,Cs) Compounds: Synthesis and Crystal Structure of Cs6 [(UO2)2(MoO4)3(MoO5)] .

Single crystals of the title compound are obtained from a melt of U₃O₈, MoO₃, and excess Cs₂CO₃ (Pt crucible, 950 °C, 12 h, cooling rate 5 °C/h).     

Phase equilibrium in the Cs2MoO4-Bi2(MoO4)3-Zn(MoO4)2 system and the crystal structure of new triple molybdate Cs5BiZr(MoO4)6

The subsolidus region of the Cs₂MoO₄-Bi₂(MoO₄)₃-Zr(MoO₄) system was studied by X-ray powder diffraction. Quasi-binary sections were elucidated, and triangulation performed. Triple molybdates with the component ratios 5: 1: 2 (S ₁) and 2: 1: 4 (S ₂) were prepared for the first time. Crystals of cesium bismuth zirconium molybdate of the 5: 1: 2 stoichiometry (Cs₅BiZr(MoO₄)₆) were grown from fluxed melts with spontaneous nucleation. The composition and crystal structure of this triple molybdate were refined using X-ray diffraction data (collected on X8 APEX automated diffractometer, MoK _α radiation, 2348 F(hkl), R = 0.0226). The trigonal unit cell parameters were as follows: a = b = 10.9569(2), c = 39.804(4) Å, V = 4138.4(4) ų, Z = 6, space group R $ \bar 3 The subsolidus region of the Cs₂MoO₄-Bi₂(MoO₄)₃-Zr(MoO₄) system was studied by X-ray powder diffraction. Quasi-binary sections were elucidated, and triangulation performed. Triple molybdates with the component ratios 5: 1: 2 (S ₁) and 2: 1: 4 (S ₂) were prepared for the first time. Crystals of cesium bismuth zirconium molybdate of the 5: 1: 2 stoichiometry (Cs₅BiZr(MoO₄)₆) were grown from fluxed melts with spontaneous nucleation. The composition and crystal structure of this triple molybdate were refined using X-ray diffraction data (collected on X8 APEX automated diffractometer, MoK _α radiation, 2348 F(hkl), R = 0.0226). The trigonal unit cell parameters were as follows: a = b = 10.9569(2), c = 39.804(4) ?, V = 4138.4(4) ?³, Z = 6, space group R c. The mixed-metal three-dimensional framework in this structure is built of Mo tetrahedra and two sorts of (Bi,Zr)O₆ octahedra. Large interstices accommodate two sorts of cesium atoms. The Bi³⁺ and Zr⁴⁺ cation distributions over two positions were refined during structure solution. Original Russian Text ? B.G. Bazarov, T.V. Namsaraeva, R.F. Klevtsova, A.G. Anshits, T.A. Vereshchagina, R.V. Kurbatov, L.A. Glinskaya, K.N. Fedorov, Zh.G. Bazarova, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 9, pp. 1585–1589.     

Phase formation in the Rb2MoO4-Er2(MoO4)3-Hf(MoO4)2 system and the crystal structure of new triple molybdate Rb5ErHf(MoO4)6

The subsolidus region of the Rb₂MoO₄-Er₂(MoO₄)₃-Hf(MoO₄)₂ ternary salt system is studied using X-ray powder diffraction. A novel 5: 1: 2 triple molybdate, Rb₅ErHf(MoO₄)₆, is found to form in the system. Crystals of Rb₅ErHf(MoO₄)₆ are flux-grown under spontaneous nucleation conditions. The composition and crystal structure of Rb₅ErHf(MoO₄)₆ are refined in a single-crystal X-ray diffraction experiment (X8 APEX diffractometer, MoK _α radiation, 1753 reflections, R = 0.0183). The crystals are trigonal; a = 10.7511(1) Å, c = 38.6543(7) Å, V = 3869.31(9) ų, d _calc = 4.462 g/cm³, Z = 6, space group $R\bar 3c$ . The mixed three-dimensional framework of the structure is formed of MoO₄ tetrahedra, each sharing corners with two ErO₆ and HfO₆ octahedra. Two types of Rb atoms occupy large cavities of the framework. The distribution of the Er³⁺ and Hf⁴⁺ cation over two positions is refined in the course of structure solution.     

Binary molybdates K4M2+(MoO4)3 (M2+=Mg, Mn, Co) and crystal structure of K4Mn(MoO4)3

Binary molybdates K₄M²⁺ (MoO₄)₃ (M²⁺=Mg, Mn, Co) isostructural to triclinic \ga-K₄Zn(WO₄)₃ were synthesized, and optimal conditions for their spontaneous crystallization were found. It was established by XRPA and DTA that at 530°C the structure of the compound with cobalt undergoes a transition to the orthorhombic structure of K₄Zn(MoO₄)₃. The structure of K₄Mn(MoO₄)₃ was determined from single crystal diffraction data (a=7.613, b=9.955, c=10.156 Å,α=92.28,β=106.66,γ=105.58°, Z=2, space group $P\bar 1$ , R=0.030). In this compound, Mn has a higher coordination number (CN=5+1) than that of Zn inα-K₄Zn(WO₄)₃ (CN=4+1). The main structural feature is pairs of MnO₆ octahedra linked by the bridging MoO₄ tetrahedra into ribbons stretching along the a axis. The structure is compared with related structures of binary molybdates and other members of the alluaudite family.     

New MoO3 Phase:Synthesis and Structure of (NH4)0.66MoO3

Gentle reduction of solid MoO₃ leads to four distinct phase of H_xMoO₃. These compounds have a wide range of colors and crystal classes:phase Ⅰ (0.25< x< 0.40), blue, orthorhombic; phase Ⅱ (0.85< x< 1.04), blue, monoclinic; phase Ⅲ (1.55< x< 1.72), red, monoclinic; and phase Ⅳ (x=2.0), green, monoclinic^[1-3]. We have now obtained a new MoO₃ phase (NH₄)MoO₃ with network structure from an aqueous solution of Na₂MoO₄ reduced by NH₂NH₂·2HC1 at 170℃.     

Crystal structure investigation of ternary molybdate K5(Mn0.5Zr1.5).(MoO4)6

Crystals of K₅(Mn_0.5Zr_1.5).(MoO₄)₆ were grown, and the crystal structure of this compound was refined in an X-ray diffraction study (CAD-4 automatic diffractometer, MoK_α radiation, 1183 |F(hkl)|, R=0.027). The parameters of the trigonal unit cell are: a=b=10.584(1); c=37.576(3) Å; V=3645.4(3) ų; space group R3c; d_calc=3.606 g/cm³. In the structure, the altermating Mo tetrahedra and (Mn, Zr) octahedra form a three-dimensional mixed framework whosevoids contain potassium atoms of three types. The distribution of the Mn and Zr cations in two crystallographic positions has been refined.