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A first cadmium copper selenite–bromide Cd7Cu2(SeO3)8Br2 (1) was obtained via chemical vapor transport reactions. The new compound is triclinic, P 1 ‾ , a = 5.3280(5) Å, b = 10.6190(12) Å, c = 11.4380(13) Å, α = 100.856(4)°, β = 93.321(4)°, γ = 91.021(4)°, V = 634.22(12) Å3, R1 = 0.027. 1 has no structural analogs and belongs to a new structure type. The structure of 1 can be described as a host-guest architecture. The host is the [Cd7(SeO3)8]2− interrupted framework, which consists of zigzag layers with a large aperture. The guests are copper bromide species. Thus, the formula can be written as [Cd7(SeO3)8]{Cu2Br2}. [ABSTRACT FROM AUTHOR]

A first cadmium copper selenite–bromide Cd7Cu2(SeO3)8Br2 (1) was obtained via chemical vapor transport reactions. The new compound is triclinic, P 1 ‾ , a = 5.3280(5) Å, b = 10.6190(12) Å, c = 11.4380(13) Å, α = 100.856(4)°, β = 93.321(4)°, γ = 91.021(4)°, V = 634.22(12) Å3, R1 = 0.027. 1 has no structural analogs and belongs to a new structure type. The structure of 1 can be described as a host-guest architecture. The host is the [Cd7(SeO3)8]2− interrupted framework, which consists of zigzag layers with a large aperture. The guests are copper bromide species. Thus, the formula can be written as [Cd7(SeO3)8]{Cu2Br2}. [ABSTRACT FROM AUTHOR]

A new uranyl silicate Cs4[(UO2)5(SiO3OH)2O2F4] (1), was obtained via a hydrothermal route. The new compound is monoclinic, P21/n, a = 8.3870(2), b = 13.4612(2), c = 10.9503(2) Å, β = 91.223(2)°, V = 1236.00(4) Å3; the structure has been solved and refined down to R1 = 0.022. Therein, the phosphouranylite units (PUs) associate into a new type of uranyl-silicate layers, [(UO2)5(SiO3OH)2O2F4]4−, which interleave with the Cs+ cations. Topological analysis of PU based structures indicates that these layers in 1 provide a unique example of complexes constructed only via association of the PU and not involving other building units. [ABSTRACT FROM AUTHOR]

A new uranyl silicate Cs4[(UO2)5(SiO3OH)2O2F4] (1), was obtained via a hydrothermal route. The new compound is monoclinic, P21/n, a = 8.3870(2), b = 13.4612(2), c = 10.9503(2) Å, β = 91.223(2)°, V = 1236.00(4) Å3; the structure has been solved and refined down to R1 = 0.022. Therein, the phosphouranylite units (PUs) associate into a new type of uranyl-silicate layers, [(UO2)5(SiO3OH)2O2F4]4−, which interleave with the Cs+ cations. Topological analysis of PU based structures indicates that these layers in 1 provide a unique example of complexes constructed only via association of the PU and not involving other building units. [ABSTRACT FROM AUTHOR]

Thermal behavior of vergasovaite, ideally Cu3O(SO4)(MoO4), and its synthetic analog has been studied by high-temperature single-crystal X-ray diffraction in the temperature range of 300–1100 K. According to EMPA results, the empirical formulas are (Cu2.36Zn0.61)Σ2.97O[(Mo0.91S0.08V0.04)Σ1.03O4](SO4) for vergasovaite and Cu2.97O[(Mo0.92S0.09)Σ1.01O4](SO4) for its synthetic analog. The mineral is stable up to 950 ± 15 K; at 975 K, the unit-cell parameters and volume increase abruptly due to topotactic transformation of vergasovaite to cupromolybdite, Cu3O(MoO4)2. The transformation is accompanied by loss of sulfur (and excess copper) without destruction of the crystal. The thermal expansion of the vergasovaite structure is strongly anisotropic, being minimal along the [O2Cu6]8+ chains comprised of vertex-sharing OCu4 tetrahedra. This peculiar thermal behavior can be explained by the anisotropy of bond-length evolution in the Cu1O6 and Cu3O6 octahedra and the flexibility of the S-O-Cu and Mo-O-Cu bond angles. Synthetic Zn- and V-free analogs demonstrate negative thermal expansion at 425–625 K and melt at as low temperature as 700 K with no indication of transformation or recrystallization at least below 1200 K. The topotactic transformation observed in vergasovaite may have important implications for the design of novel materials and for understanding the alteration processes of copper minerals. [ABSTRACT FROM AUTHOR]

Napoliite, ideally Pb2OFCl, is a new fluoroxychloride mineral found in a specimen from a fumarole formed subsequent to the 1944 eruption of Vesuvius volcano, Naples Province, Italy. It occurs as well-shaped lamellar crystals up to 0.25 × 0.25 × 0.01 mm typically forming clusters up to 0.4 × 0.4 mm on the surface of volcanic scoria in association with anglesite, artroeite, atacamite, calcioaravaipaite, cerussite, challacolloite, cotunnite, hephaistosite, manuelarossiite, matlockite and susannite. Napoliite is colourless with white streak and adamantine lustre. It is brittle and has a laminated fracture. Cleavage is perfect on {001}. D calc = 7.797 g cm–3. The calculated mean refractive index is 2.10. Chemical composition (wt.%, electron microprobe) is: PbO 91.71, F 3.89, Cl 7.34, –O=(F+Cl) –3.30, total 99.64. The empirical formula calculated on the basis of 3 anions is Pb1.999O0.997F0.996Cl1.007. Raman spectroscopy confirms the absence of OH– groups and H2O molecules in the mineral. Napoliite is tetragonal, space group P 42/ mcm , a = 5.7418(11), c = 12.524(4) Å, V = 412.9(2) Å3 and Z = 4. The strongest lines of the powder X-ray diffraction pattern [ d , Å (I , %) (hkl)] are: 3.860 (85) (111); 3.139 (20) (004); 2.914 (100) (113); 2.866 (63) (200); 2.118 (19) (204); 2.027 (19) (220); 1.665 (20) (313); and 1.642 (23) (117). The crystal structure was refined to R 1 = 0.024 for 222 reflections with F > 4σ(F). It is based on lead oxide blocks derived from that of litharge PbO, which alternate with layers of chloride ions. Napoliite represents a new structure type with a unique order/disorder pattern of fluorine and oxygen atoms. The new mineral is dimorphous with rumseyite. It is named after the city of Naples (Napoli in Italian). [ABSTRACT FROM AUTHOR]

A new rubidium uranyl silicate, Rb2(UO2)2O(Si3O8) (1), was obtained using high-temperature approach from the melt in silica tubes. Its crystal structure was solved by direct methods: hexagonal, P6/m, a = 27.7992(7), c = 7.2346(2) Å, V = 4841.8(3) Å3, R1 = 0.033. The structure of 1 represents a new structure type with unprecedented topology not observed before among U(VI) oxides and oxysalts. It is comprised of layers with large voids derived from the U3O8 structure formed exclusively by pentagonal UrO5 bipyramids. The low-occupied Rb sites are located in the interlayer space. The SiO4 silicate tetrahedra in the structure of 1 share vertices to form rolled [Si6O16]8− chains. The nanotubules [(UO2)(Si6O16)]6− penetrate through both U3O8-derived layers and Rb interlayer. These tubules are attached to the U3O8 derived sheets via uranyl-uranyl interactions and edge-sharing between silicate tetrahedra and UrO5 bipyramids. [ABSTRACT FROM AUTHOR]

To date, uranyl silicates are mostly represented by minerals in nature. However, their synthetic counterparts can be used as ion exchange materials. A new approach for the synthesis of framework uranyl silicates is reported. The new compounds Rb2[(UO2)2(Si8O19)](H2O)2.5 (1), (K,Rb)2[(UO2)(Si10O22)] (2), [Rb3Cl][(UO2)(Si4O10)] (3) and [Cs3Cl][(UO2)(Si4O10)] (4) were prepared at harsh conditions in "activated" silica tubes at 900 °C. The activation of silica was performed using 40% hydrofluoric acid and lead oxide. Crystal structures of new uranyl silicates were solved by direct methods and refined: 1 is orthorhombic, Cmce, a = 14.5795(2) Å, b = 14.2083(2) Å, c = 23.1412(4) Å, V = 4793.70(13) Å3, R1 = 0.023; 2 is monoclinic, C2/m, a = 23.0027(8) Å, b = 8.0983(3) Å, c = 11.9736(4) Å, β = 90.372(3) °, V = 2230.43(14) Å3, R1 = 0.034; 3 is orthorhombic, Imma, a = 15.2712(12) Å, b = 7.9647(8) Å, c = 12.4607(9) Å, V = 1515.6(2) Å3, R1 = 0.035, 4 is orthorhombic, Imma, a = 15.4148(8) Å, b = 7.9229(4) Å, c = 13.0214(7) Å, V = 1590.30(14) Å3, R1 = 0.020. Their framework crystal structures contain channels up to 11.62 × 10.54 Å filled by various alkali metals. [ABSTRACT FROM AUTHOR]

Polythermic single-crystal X-ray studies of chalcocyanite CuSO4, dolerophanite Cu2OSO4, and kamchatkite KCu3O(SO4)2Cl have established their melting points as well as peculiarities of their thermal expansion. Association of oxocentered and sulfate tetrahedra in dolerophanite and kamchatkite leads to the formation of rigid tetrahedral "backbones" only slightly sensitive to thermal variations. Rigid complexes can also be distinguished in the structure of chalcocyanite, if we consider only the system of the shortest and strongest Cu–O and S–O bonds. The anisotropy of the thermal expansion can be explained by either rigid complexes drifting parallel to each other (as in dolerophanite and chalcocyanite), or radial and angular distortions in the polyhedra of alkali cations. The presence of a tetrahedrally coordinated additional oxygen atom in the structure of dolerophanite and kamchatkite leads to an increase in the principal eigenvalues. The demonstrated rigidity of the sulfate tetrahedra in studied anhydrous copper sulfate minerals explains the absence of phase transitions up to the melting temperatures. The variation of chemical composition leads to changes in their thermal decomposition points. Chlorine-containing kamchatkite decomposes at the lowest temperature of 590(5) K, next are chalcocyanite 675(10) K, and dolerophanite 925(10) K. [ABSTRACT FROM AUTHOR]

Three new copper-lead selenite bromides were synthesized by chemical vapor transport reactions. Pb5Cu+4(SeO3)4Br6 is monoclinic, space group C2/m, a = 17.7248(14), b = 5.5484(5), c = 12.7010(10) Å, β = 103.398(2)º, V = 1215.08(17) Å3, R1 = 0.024; Pb8Cu2+(SeO3)4Br10 is orthorhombic, space group I222, a = 9.5893(5), b = 12.4484(9), c = 12.7927(6) Å, V = 1527.08(15) Å3, R1 = 0.027; Pb5Cu2+(SeO3)4(Br,Cl)4 is monoclinic, C2/c, a = 24.590(6) Å, b = 5.5786(14) Å, c = 14.248(4) Å, β = 102.883(7)º, V = 1905.3(9) Å3, R1 = 0.026. The crystal structure of Pb5Cu+4(SeO3)4Br6 consists of two distinct parts: corner- and edge-sharing Cu+Br4 tetrahedra form infinite [Cu+4Br6]2- layers which alternate with [Pb5(SeO3)4]2+ layers. Pb8Cu2+(SeO3)4Br10 contains positively charged unique [Pb8Cu2+(SeO3)4]10+ rod-like chains with Cu2+ cations in the core. These chains are held together by Br- anions. Pb5Cu+4(SeO3)4Br6 and Pb8Cu2+(SeO3)4Br10 belong to new structure types. Pb5Cu2+(SeO3)4(Br,Cl)4 is a synthetic analogue of the mineral sarrabusite, Pb5Cu(SeO3)4Cl4, previously known from an electron diffraction study. The investigation of this synthetic equivalent of sarrabusite by conventional single-crystal X-ray diffraction provides a distinctly improved insight in this crystal structure. Cu atom has well-defined [2O+(2O+2X)] (X = halogen) distorted octahedral coordination. PbOn and SeO3 polyhedra interconnect via common oxygen atoms into [Pb5(SeO3)4]2+ layers parallel to (001). Cu2+ cations interconnect the layers into the framework with the large cavities filled by halide X anions. In all three new compounds described, a common feature is the formation of the selenophile substructure which is terminated by a 'lone-pair' shell that faces bromide complexes thus forming the surface of a halophile substructure. [ABSTRACT FROM AUTHOR]

Crystals of two new polymorphic forms of the known compound (NaCl)[Cu(HSeO3)2], which we term polymorphs II and III, were formed after a ca. one-year dwelling of a crystalline precipitate under mother liquor and upon crystallization in the presence of K+, respectively. Both structures belong to the "layered copper hydroselenite" family. The polymorph II is a structural analog of (KCl)[Cu(HSeO3)2] with a fully ordered Na+ site; the main difference concerns the environment of Cu2+ which is more regular in (NaCl)[Cu(HSeO3)2]-II. In contrast to some expectations, crystallization from solutions containing KCl. NaCl, CuCl2, and H2SeO3 upon evaporation does not result in formation of mixed (Na1−xKxCl)[Cu(HSeO3)2] crystals, but rather in a separate crystallization of (KCl)[Cu(HSeO3)2] and (NaCl)[Cu(HSeO3)2]-III which exhibits a complex structure with four ordered and one disordered Na+ sites. It is possible that longer crystallization times enhance formation of ordered structures. [ABSTRACT FROM AUTHOR]