Synthesis, X-ray and Neutron Diffraction Characterization, and Ionic Conduction Properties of a New Oxothiomolybdate Li3[Mo8S8O8(OH)8{HWO5(H2O)}]⋅18 H2O
“…It was observed that the samples are highly resistive (sheet resistance ∼18 GΩ/sq). The result is within the expected range as reported in an earlier study by Dolbecq et al, 63 where they also found such high resistance of the polytungstate material. building units and Mn 2+ as linker have been successfully synthesized by a unique solvothermal method at 180 °C using a 1:1 water−ethanol mixed solvent.…”
An uncommon yet highly symmetric crystal form of a Mn-based heteropolytungstate (Mn-HPT), Mn 7 (MnW 12 O 42 (OH) 4 )• 8H 2 O, has been synthesized by a unique solvothermal method at 180 °C for 6 h. The nature of the solvent (water/ethanol = 50/50 by volume) and the presence of citric acid were the key reasons for the formation of the Mn-HPT phase and its hollow spherical morphology under the said experimental conditions. Combined powder X-ray diffraction analysis and field emission scanning electron miroscopy (FESEM) analysis reveals that the structure (cubic, space group Im3) consisted of [MnW 12 O 42 ] 10− polyanion with Mn in a central 12coordinated cavity, which cross-linked three dimensionally with other MnO 6 octahedra, to form the characteristic rhombododecahedron shaped particles of size ∼150 nm. Each polyanion was made of six pair of face shared WO 6 dimers (W 2 O 9 ) with mean W•••W separation of 2.98 Å. The WO 6 octahedrons were tilted to an O−W−O angle of 99.1°with four different types of W−O bonds. The structure was further characterized by thermogravimetric (TG), infrared (IR), Raman, and X-ray photoelectron spectroscopy (XPS) study. UV−vis diffuse reflectance spectroscopy (DRS) analysis suggests that the material essentially was an indirect band gap semiconductor with E g = 2.33 and 2.93 eV corresponding to the transitions from two different sets of nonbonding HOMO (O 2p) to the π* LUMO (W 5d). Room temperature photoluminescence (PL) analysis further delineates the HOMO−LUMO transition in the blue (412 nm) to green (525 nm) region with characteristic mean decay lifetime ∼8 ns.
“…It was observed that the samples are highly resistive (sheet resistance ∼18 GΩ/sq). The result is within the expected range as reported in an earlier study by Dolbecq et al, 63 where they also found such high resistance of the polytungstate material. building units and Mn 2+ as linker have been successfully synthesized by a unique solvothermal method at 180 °C using a 1:1 water−ethanol mixed solvent.…”
An uncommon yet highly symmetric crystal form of a Mn-based heteropolytungstate (Mn-HPT), Mn 7 (MnW 12 O 42 (OH) 4 )• 8H 2 O, has been synthesized by a unique solvothermal method at 180 °C for 6 h. The nature of the solvent (water/ethanol = 50/50 by volume) and the presence of citric acid were the key reasons for the formation of the Mn-HPT phase and its hollow spherical morphology under the said experimental conditions. Combined powder X-ray diffraction analysis and field emission scanning electron miroscopy (FESEM) analysis reveals that the structure (cubic, space group Im3) consisted of [MnW 12 O 42 ] 10− polyanion with Mn in a central 12coordinated cavity, which cross-linked three dimensionally with other MnO 6 octahedra, to form the characteristic rhombododecahedron shaped particles of size ∼150 nm. Each polyanion was made of six pair of face shared WO 6 dimers (W 2 O 9 ) with mean W•••W separation of 2.98 Å. The WO 6 octahedrons were tilted to an O−W−O angle of 99.1°with four different types of W−O bonds. The structure was further characterized by thermogravimetric (TG), infrared (IR), Raman, and X-ray photoelectron spectroscopy (XPS) study. UV−vis diffuse reflectance spectroscopy (DRS) analysis suggests that the material essentially was an indirect band gap semiconductor with E g = 2.33 and 2.93 eV corresponding to the transitions from two different sets of nonbonding HOMO (O 2p) to the π* LUMO (W 5d). Room temperature photoluminescence (PL) analysis further delineates the HOMO−LUMO transition in the blue (412 nm) to green (525 nm) region with characteristic mean decay lifetime ∼8 ns.
“…When sodium tungstate, selenium dioxide, and K 2−x (NMe 4 ) x [I 2 Mo 10 O 10 S 10 (OH) 10 -(H 2 O) 5 ]•20H 2 O were mixed in water at pH 3.5, the resulting solution turned red, a color typical of the reaction of nucleophilic [Mo 2 O 2 S 2 ]2+ clusters with vacant polyoxotungstates 10,11,28,29. At this pH, the condensation process of 2 O 2 S 2 ] 2+ complexes can also occur to give cyclic assemblies around various ligands9,30 and especially around the monotungstate group, which leads to the formation of the very stable y e l l o w -o r a n g e c o m p o u n d [ M o 8 O 8 S 8 ( O H ) 8 -(HWO 5 (H 2 O))] 3− 31. This species was evidenced by the formation of a yellow precipitate during the synthesis when the reactants were introduced in stoichiometric ratios.…”
Self-assembly reactions of NaWO, SeO/SeO, and [MoO(μ-S)(HO)] give, depending on the pH value, two new large polyoxometalate complexes: i.e., [(γ-SeWO)(MoO(μ-S)(HO))] (1) isolated at pH 3.5 and [(γ-SeWO)(WO(HO))(WO)(WO)(MoO(μ-S)(HO))(MoO(μ-S)(SeO))] (2) isolated at pH 2. Both compounds were characterized in the solid state by single-crystal X-ray diffraction, EDX, elemental analysis, TGA, and FT-IR and in solution by ESI-MS and NMR.
“…Other modes of fusion are more typical for most of the known small rings of octahedra. Some examples are rings of six edge-sharing octahedra, [PMo 6 O 22 (O 3 POH) 3 ] 9- (Figure b), and rings of eight octahedra that share alternatingly faces and edges, [WMo 8 S 8 O 11 (OH) 11 ] 3- (Figure c) . The higher degree of fusion observed in the last two examples is needed most likely because of the small number of MoO 6 oxygen atoms that are shared with other groups, i.e., only six with the phosphate groups in [PMo 6 O 22 (O 3 POH) 3 ] 9- and none in [WMo 8 S 8 O 11 (OH) 11 ] 3- .…”
Section: Resultsmentioning
confidence: 99%
“… 1 Two views of the isolated ring 1 made of eight MoO 6 octahedra that alternatingly share corners and edges and four phenyldiphosphonate groups: (a) the center of the ring is open; (b) the ring is puckered with approximate symmetry of D 2 d . 2 Various small rings with different connectivity between the octahedra: (a) [MoMo 6 O 16 (O 3 PCH 2 PO 3 ) 3 ] 8- with alternatingly shared corners and edges; (b) [PMo 6 O 22 (O 3 POH) 3 ] 9- with shared edges only; (c) [WMo 8 S 8 O 11 (OH) 11 ] 3- with alternatingly shared edges and faces …”
Section: Resultsmentioning
confidence: 99%
“…Various small rings with different connectivity between the octahedra: (a) [MoMo 6 O 16 (O 3 PCH 2 PO 3 ) 3 ] 8- with alternatingly shared corners and edges; (b) [PMo 6 O 22 (O 3 POH) 3 ] 9- with shared edges only; (c) [WMo 8 S 8 O 11 (OH) 11 ] 3- with alternatingly shared edges and faces …”
A novel mixed-valence polyoxomolybdenum anion, [Mo(V)(7)Mo(VI)O(16)(O(3)PPhPO(3)H)(4)](3)(-), was synthesized hydrothermally from molybdenum oxide, molybdenum metal, boric and phosphoric acids, 1,2-phenyldiphosphonic acid, and imidazole (ImH) and was structurally characterized as an imidazolium salt (orthorhombic, Aba2; a = 16.674(4), b = 17.238(1), and c = 24.81(2) A). One- and two-dimensional structures of this anion and additional molybdenum diphosphonate linkers were assembled as well. They were structurally characterized as their pyridinium (pyH) salts (pyH)(4)[[Mo(V)(7)Mo(VI)O(16)(O(3)PPhPO(3))(2)(O(3)PPhPO(3)H)(2)][Mo(2)O(4)(OH)(HO(3)PPhPO(3)H)]].5H(2)O (monoclinic, P2(1)/c; a = 20.8506(9), b = 22.866(1), and c = 21.1403(9) A; beta = 118.7087(8) degrees ) and (pyH)(3)[[Mo(V)(7)Mo(VI)O(16)(O(3)PPhPO(3))(4)][Mo(2)O(2)(OH)(2)(HO(3)PPhPO(3)H)]].3H(2)O (orthorhombic, Pca2(1); a = 19.057(1), b = 20.402(2), and c = 20.660(2) A). The compounds were also characterized by IR spectroscopy and magnetic measurements.
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