Hydrolysis of ammonium oxofluorotungstates: A 19F, 17O and 183W NMR study

Fedotov, M. A.; Kon'shin, V. V.; Laptash, N. M.

doi:10.1016/j.jfluchem.2010.02.002

Cited by 4 publications

(3 citation statements)

References 13 publications

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“…The movie is presented for simplicity without Na atoms and in 2D, whereby the left side connects to the right side at the front. The positioning of one {W 2 } molecule that is shifted by half the height of the supramolecular structure may be due to crowding and can be observed also in the crystal structure of the dimeric species K 3 [Nb 2 O 2 F 9 ], in which two such shifted molecules occur . Note that the rotation by 90° of the hexameric supramolecular structure of six {W 2 } species is in a good structural correlation with the {W 12 } intermediate and the belt of the final [H 2 F 6 NaW 18 O 56 ] 7− anion, except for the lacunary position caused by the shift of one tungsten atom into the cap position.…”

Section: Resultsmentioning

confidence: 78%

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Self‐Assembly through Noncovalent Preorganization of Reactants: Explaining the Formation of a Polyfluoroxometalate

Schreiber

Avram

Neumann

2017

Chemistry A European J

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High-order elementary reactions in homogeneous solutions involving more than two molecules are statistically improbable and very slow to proceed. They are not generally considered in classical transition-state or collision theories. Yet, rather selective, high-yield product formation is common in self-assembly processes that require many reaction steps. On the basis of recent observations of crystallization as well as reactions in dense phases, it is shown that self-assembly can occur by preorganization of reactants in a noncovalent supramolecular assembly, whereby directing forces can lead to an apparent one-step transformation of multiple reactants. A simple and general kinetic model for multiple reactant transformation in a dense phase that can account for many-bodied transformations was developed. Furthermore, the self-assembly of polyfluoroxometalate anion [H F NaW O ] from simple tungstate Na WO F was demonstrated by using 2D F- F NOESY, 2D F- F COSY NMR spectroscopy, a new 2D F{ W} NMR technique, as well as ESI-MS and diffusion NMR spectroscopy, and the crucial involvement of a supramolecular assembly was found. The deterministic kinetic reaction model explains the reaction in a dense phase and supports the suggested self-assembly mechanism. Reactions in dense phases may be of general importance in understanding other self-assembly reactions.

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Section: Resultsmentioning

confidence: 78%

“…The formation of various {W 2 } species by defluorination of (NH 4 ) 2 WO 2 F 4 with AlCl 3 or NH 4 OH was reported in the literature . Addition of AlCl 3 yielded the trans , mer ‐[W 2 O 5 F 6 ] 4− anion, while addition of NH 4 OH yielded the fac ‐[W 2 O 5 F 6 ] 4− isomer.…”

Section: Resultsmentioning

confidence: 85%

Self‐Assembly through Noncovalent Preorganization of Reactants: Explaining the Formation of a Polyfluoroxometalate

Schreiber

Avram

Neumann

2017

Chemistry A European J

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“…As a result, the oxide and fluoride ions retain unequal amounts of residual negative charge that impacts on how they coordinate with the surrounding cations. The trans-or cis-directing properties of different MO x F 2À 6Àx anions can be exploited for an explanation of their hydrolytic behavior characterized by oligomerization processes (Fedotov et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Dinuclear oxofluorometallates as a new structural type of d ⁰ transition metal oxofluoride compound

Udovenko

Laptash

2012

Acta Crystallogr Sect B

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Five isomorphous d(0) transition metal oxofluoride compounds A(3)[M(2)O(x)F(11-x)]·(AF)(0.333) (A = K, Rb, NH(4); M = Nb, Mo, W; x = 2, 4) have been synthesized from acid fluoride solutions, and their crystal structures have been determined by single-crystal X-ray diffraction. The basic structural building units are dinuclear M(2)X(11) (dimers) formed from NbOF(5) or Mo(W)O(2)F(4) octahedra connected by the fluorine bridging atom. In the Nb(2)O(2)F(9) dimer, the O atoms occupy apical corners. In the M(2)O(4)F(7) (M = Mo, W) dimers two O atoms are also apically placed, whereas the other two O atoms are statistically disordered in equatorial planes. The arrangement of dimers is so that the hexagonal tunnels containing `free' fluoride ions are formed. During the irradiation process the orthorhombic structure of K(3)Nb(2)O(2)F(9)·(KF)(0.333) transforms into a pseudo-trigonal one with a = 23.15 Å, which is the [101] diagonal of the orthorhombic unit cell. The other four trigonal crystals are merohedral twins.

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Ammonium Transport Simulation in Horizontal Soil Columns from a Natural Inland Alkaline Wetland

Bai

Xiao

et al. 2013

CLEAN Soil Air Water

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Ammonium transport was simulated in horizontal soil columns from an inland alkaline wetland (Fulaowenpao wetland) of Northeast China. The primary objectives of this work are to investigate the changes in ammonium transport rate with increasing distances along horizontal soil column and to determine the effects of water diffusion rate and volumetric water content on ammonium transport rate. Our results showed that water diffusion coefficient was the lowest at the soil layer of 10–20 cm, followed by the 0–10 cm soil layer, and the highest value occured at the soil layer of 20–60 cm. The highest ammonium transport rate also appeared at the soil layer of 20–60 cm, while the lowest value was observed at the soil layer of 10–20 cm. Ammonium transport rates decreased with increasing distances along horizontal soil columns. The ammonium transport rates showed higher values at the distance from 0 to 6 cm and then decreased rapidly from 6 to 18 cm. However, they nearly kept constant and approached to zero after exceeding the distance of 18 cm. Ammonium transport rates increased exponentially with increasing volumetric water contents and water diffusion rates. The alkaline wetland soils prevented ammonium from horizontal diffusion at all soil layers under drying conditions.

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Hydrolysis of ammonium oxofluorotungstates: A 19F, 17O and 183W NMR study

Cited by 4 publications

References 13 publications

Self‐Assembly through Noncovalent Preorganization of Reactants: Explaining the Formation of a Polyfluoroxometalate

Self‐Assembly through Noncovalent Preorganization of Reactants: Explaining the Formation of a Polyfluoroxometalate

Dinuclear oxofluorometallates as a new structural type of d ⁰ transition metal oxofluoride compound

Ammonium Transport Simulation in Horizontal Soil Columns from a Natural Inland Alkaline Wetland

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Hydrolysis of ammonium oxofluorotungstates: A 19F, 17O and 183W NMR study

Cited by 4 publications

References 13 publications

Self‐Assembly through Noncovalent Preorganization of Reactants: Explaining the Formation of a Polyfluoroxometalate

Self‐Assembly through Noncovalent Preorganization of Reactants: Explaining the Formation of a Polyfluoroxometalate

Dinuclear oxofluorometallates as a new structural type of d 0 transition metal oxofluoride compound

Ammonium Transport Simulation in Horizontal Soil Columns from a Natural Inland Alkaline Wetland

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Dinuclear oxofluorometallates as a new structural type of d ⁰ transition metal oxofluoride compound