نتایج جستجو برای: α keggin
تعداد نتایج: 165395 فیلتر نتایج به سال:
In the title salt, [Eu(C3H7NO)8][PMo12O40], the asymmetric unit comprises one α-Keggin-type [PMo12O40](3-) polyoxidometalate anion and one distorted dodeca-hedral [Eu(C3H7NO)8](3+) complex cation. In the crystal, the isolated polyoxidometalate anions are packed into hexa-gonally arranged rows extending parallel to [001]. The complex cations are situated between the rows and are linked to the ne...
The molecular structures and surface chemistry of mixed metal oxide heteropolyoxo vanadium tungstate (H(3+x)PW(12-x)V(x)O(40) with x = 0, 1, 2, and 3) Keggin nanoparticles (NPs), where vanadium is incorporated into the primary Keggin structure, and supported VO(x) on tungstophosphoric acid (TPA, H(3)PW(12)O(40)), where vanadium is present on the surface of the Keggin unit, were investigated wit...
The five manganese-containing, Keggin-based tungstosilicates [Mn(II)3(OH)3(H2O)3(A-α-SiW9O34)](7-) (1), [Mn(III)3(OH)3(H2O)3(A-α-SiW9O34)](4-) (2), [Mn(III)3(OH)3(H2O)3(A-β-SiW9O34)](4-) (3), [Mn(III)3Mn(IV)O3(CH3COO)3(A-α-SiW9O34)](6-) (4), and [Mn(III)3Mn(IV)O3(CH3COO)3(A-β-SiW9O34)](6-) (5) were synthesized in aqueous medium by interaction of [A-α-SiW9O34](10-) or [A-β-SiW9O34H](9-) with eit...
The asymmetric unit of the title compound, [Fe(C(8)H(7)N(3))(3)](2)[SiMo(14)O(44)], consists of a complex [Fe(C(8)H(7)N(3))(3)](2+) cation and half of a derivative of an α-Keggin-type anion, [SiMo(14)O(44)](4-). In the mixed-valent Mo(V/VI) anion, the α-Keggin type core is capped on two oppositely disposed tetra-gonal faces by additional (MoO(2)) units. The [SiMo(14)O(44)](4-) anion shows disor...
Two dysprosium-containing tungstoarsenates [C(NH(2))(3)](11)[Dy(2)(Hcit)(2)(AsW(10)O(38))]·9H(2)O (1) and K(8-n)H(3-n)[Dy(3-n)K(n)(H(2)O)(3)(CO(3))(A-α-AsW(9)O(34))(A-β-AsW(9)O(34))]·22H(2)O (n = 0 or 1) (2) have been synthesized and characterized by single-crystal X-ray diffraction, elemental analyses, thermogravimetric analyses and infrared spectroscopy. Compound 1 is a citrate-decorated Kegg...
The structural evolution of Keggin-type heteropolyoxomolybdates (HPOM) during thermal treatment in propene and in propene and oxygen in the temperature range from 300 to 773 K was investigated by in situ X-ray diffraction (XRD) and in situ X-ray absorption spectroscopy (XAS) combined with mass spectrometry. During treatment in propene or hydrogen and at reaction temperatures above 673 K, the in...
Titania supported vanadomolybdophosphoric acid (VMPA) catalysts with vanadium in different positions, incorporated into the molybdophosphoric acid structure by substituting for molybdenum and cation exchanged on the molybdophosphoric acid surface, were synthesized. The catalysts were characterized by XRD, FT-IR, Raman spectroscopy, TPR, XPS, and ESR techniques. The FT-IR and Raman spectral anal...
Molybdenum-based Keggin polyoxometalates (POMs) containing vanadium, with the formula H3+xPMo12 xVxO40 (MPAV) and x varying from0 to 3, exhibit unique catalytic properties because of their bifunctional nature and have been investigated as catalysts both for acidic and for oxidative reactions. 3 The addition of vanadium centers are beneficial for redox catalysis, shifting the molybdophosphoric a...
The crystal structure of the title compound, (C(6)H(12)N(5)O)(4)[W(12)(SiO(4))O(36)]·6H(2)O, consists of an α-Keggin-type [W(12)(SiO(4))O(36)](4-) polyoxidoanion, four [(2H-tetra-zol-5-yl)meth-yl]morpholinium cations and six uncoordinated water mol-ecules. In the cations, the morpholine rings display chair conformations. Extensive N-H⋯O, N-H⋯N, O-H⋯O and O-H⋯N hydrogen bonds are present in the ...
The asymmetric unit of the polyoxidometalate-based organic-inorganic hybrid title compound, (C(3)H(10)NO)(3)[PMo(12)O(40)]·3H(2)O, consists of one α-Keggin-type [PMo(12)O(40)](3-) polyoxido-anion, three independent [CH(3)-O-CH(2)-CH(2)-NH(3)](+) cations and three solvent water mol-ecules. The polyoxidoanion shows characteristic features with respect to bond lengths and angles. In the crystal st...
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