Kristallstrukturen zweier Modifikationen von In5Mo18O28 und deren Zwillingsbildung

Crystal Structures of Two Forms of In₅Mo₁₈O₂₈ and Twinning In₅Mo₁₈O₂₈ is prepared from In, Mo and MoO₂ at 1 150°C in an evacuated quartz glass ampoule. X-ray investigations on single crystals show monoclinic symmetry (a = 1 323.13(9), b = 951.88(10), c = 989.48(8) pm, β = 100.976(4)°, space group P 2₁/c (No. 14)) for form 1 . The second form ( 2 ) crystallizes in the orthorhombic system (space group Pmcn (No. 62), a = 2 596.6(5), b = 952.0(2), c = 989.6(2) pm). Twinning and charge balances are discussed.     

Synthese und Kristallstruktur von PbMo5O8; ein reduziertes Oxomolybdat mit Mo10O28-Oktaederdoppeln

Synthesis and Crystal Structure of PbMo₅O₈; a reduced Oxomolybdate with Mo₁₀O₂₈ Double Octahedra The crystal structure of the new phase PbMo₅O₈ contains oligometric Mo clusters which consist of two edge-sharing Mo₆ octahedra connected according to Mo₁₀OOO. The compound is isotypic with LaMo₅O₈. Isolated, divalent Pb atoms are located in the “channels” of the monoclinic structure (a = 999.3(2) pm, b = 924.7(1) pm, c = 753.6(2) pm, β = 109.39(2)°, P2₁/a. Compared to the compound In ₁₁Mo₄₀O₆₂ the Mo? O distances (average 206 pm) and the Mo? Mo distances within the octahedral units (average 275 pm) are slightly decreased by 1 and 4 pm, respectively. The very short Mo? Mo distances (278 pm) between the cluster units which are not observed in In₁₁Mo₄₀O₆₂ (320 pm) are due to excess electrons in these inter-cluster bonds which would otherwise occupy antibonding cluster states.     

Crystal structure, spectroscopic properties, and magnetic behavior of the fluoride-derivatized lanthanoid(III) ortho-oxomolybdates(VI) LnF[MoO4] (Ln=Sm-Tm)

The fluoride-derivatized lanthanoid(III) ortho-oxomolybdates(VI) LnF[MoO₄] (Ln=Sm-Tm) crystallize in the monoclinic space group P2₁/c with four formula units per unit cell (a=516-528 pm, b=1220-1248 pm, c=659-678 pm, β=112.5-113.1°). The structure contains one crystallographically unique Ln³⁺ cation surrounded by two fluoride and six oxide anions in a square antiprism (CN=8). The square antiprisms [LnF₂O₆] are interconnected via three edges to form layers parallel (010), which are cross-linked along [010] by Mo⁶⁺ in tetrahedral oxygen coordination to form the three-dimensional crystal structure. The fluoride anions within this arrangement exhibit a twofold coordination of Ln³⁺ cations in the shape of a boomerang, which is connected to another F⁻ anion to form planar [F₂Ln₂]⁴⁺ rhombuses. Magnetic measurements for GdF[MoO₄], TbF[MoO₄], and DyF[MoO₄] show Curie-Weiss behavior, despite the peculiar arrangement of the lanthanoid(III) cations in layers comparable with those of gray arsenic. Furthermore, Raman, infrared, and diffuse reflectance spectroscopy data for these compounds were recorded and interpreted.     

Über die Kristallstruktur von In3Mo11O17 sowie über physikalische Eigenschaften oligomerer Oxomolybdate

On the Crystal Structure of In₃Mo₁₁O₁₇ and the Physical Properties of Oligomeric Oxomolybdates In₃Mo₁₁O₁₇ is characterized by its molybdate framework Mo₂₂O₃₄^8? belonging to the general series Mo_4n+2O_6n+4^x? (with n = 5). The phase grows in star-like aggregates and crystallizes within the orthorhombic system (a = 988.0(2) pm, b = 951.2(2) pm, c = 3 176.7(4) pm). There are oligomeric clusters built from five trans edge-sharing Mo₆ octahedra, surrounded by O atoms over all empty edges according to the Aufbau principle Mo₂₂OOO. In the remaining structural channel one finds an In₆⁸⁺ polycation which is geometrically equivalent with the one of In₁₁Mo₄₀O₆₂. The Mo—O and Mo—Mo distances within the cluster are the same like in In₁₁Mo₄₀O₆₂, too, but there are shorter inter cluster distances (306 pm) in In₃Mo₁₁O₁₇. Disorder in the structure may be understood in terms of the presence of constitutional isomers. While the electrical resistivity of PbMo₅O₈ resembles the one of a strongly disturbed metal (with a local minimum around 120 K), the temperature characteristic of Tl_0.8Sn_0.6Mo₇O₁₁ is typical for a semiconductor. Oxomolybdates with even longer oligomers like In₁₁Mo₄₀O₆₂ and In₃Mo₁₁O₁₇ show metallic conductivity. This course corresponds with the sizes of the clusters and their electronic intercoupling which can be estimated from the specific lengths of the inter cluster distances. The effective magnetic moment grows with increasing cluster length from 0.97 μ_B (PbMo₅O₈) to 1.40 μ_B (In₁₁Mo₄₀O₆₂) per cluster (exception: In₃Mo₁₁O₁₂), and so does the contribution of the temperature-independent paramagnetism (from 890 to 2191 × 10^?6$ \frac{{{\rm emu}}}{{{\rm mol}}} $ per cluster). Thus, a single condensed octahedron carries roughly 440 × 10^?6$ \frac{{{\rm emu}}}{{{\rm mol}}} $ as a temperature-independent paramagnetism, similar to the M₆X₁₇ halide clusters. In₁₁Mo₄₀O₆₂ shows an interesting change in the temperature dependence of its magnetic suszeptibility.