Synthesis and characterization of the dimolybdate ion, Mo2O72-

Day, Victor W.; Fredrich, M. F.; Klemperer, W. G.; Shum, W.

doi:10.1021/ja00460a074

Cited by 85 publications

(34 citation statements)

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“…The observation of two nitrogen sites in the asymmetric unit for [ n-C 4 H 9 4 N] 2 Mo 2 O 7 may provide a supplement to the preliminary report of its crystal structure. 16 The simulated spectrum in Fig. 6 Table 1 for the two N-sites in a 1 : 0.71 ratio for N(1) and N(2).…”

Section: [(N-c 4 H 9 ) 4 N] 2 Mo 2 Omentioning

confidence: 99%

Solid‐state ¹⁴N MAS NMR of ammonium ions as a spy to structural insights for ammonium salts

Jakobsen

Hove

Hazell

et al. 2006

Magnetic Reson in Chemistry

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The high resolution offered by magic-angle spinning (MAS), when compared to the static condition in solid-state NMR of powders, has been used to full advantage in a (14)N MAS NMR study of some ammonium salts: CH(3)NH(3)Cl, (NH(4))(2)(COO)(2) x H(2)O, (CH(3))(3)(C(6)H(5)CH(2))NCl, (CH(3))(3)(C(6)H(5))NI, [(n-C(4)H(9))(4)N](2)Mo(2)O(7), (NH(4))(2)HPO(4), and NH(4)H(2)PO(4). It is shown that the high-quality (14)N MAS NMR spectra, which can be obtained for these salts, allow determination of the (14)N quadrupole coupling parameters, i.e. C(Q) (the quadrupole coupling constant) and eta(Q) (the asymmetry parameter), with very high precision. In particular, it is shown that precise C(Q), eta(Q) parameters can be determined for at least two different (14)N sites in case the individual spinning-sideband (ssb) intensities arise from a single manifold of ssbs, i.e. the ssbs for the two sites cannot be resolved. This feature of (14)N MAS NMR, which is the first demonstration for manifolds of ssb in MAS NMR without the potential information from a central transition, becomes especially useful at the slow spinning frequencies (nu(r) = 1000-1500 Hz) applied to some of the ammonium salts studied here. The detection of the number of sites has been confirmed by the corresponding crystal structures determined from single-crystal X-ray diffraction (XRD), either in this work for the unknown structure of benzyl trimethylammonium chloride or from reports in the literature. The magnitudes of the (14)N quadrupole coupling constants for the ammonium salts studied here are in the range from C(Q) approximately 20 kHz to 1 MHz while the asymmetry parameters span the full range 0 < or = eta(Q) < or = 1. Clearly, the (14)N quadrupole coupling parameters (C(Q), eta(Q)) for ammonium ions appear highly sensitive toward crystal structure and therefore appreciably more informative for the characterization of ammonium salts in comparison to the isotropic (14)N (or (15)N) chemical shifts.

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Section: [(N-c 4 H 9 ) 4 N] 2 Mo 2 Omentioning

confidence: 99%

Solid‐state ¹⁴N MAS NMR of ammonium ions as a spy to structural insights for ammonium salts

Jakobsen

Hove

Hazell

et al. 2006

Magnetic Reson in Chemistry

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“…No general agreement exists with respect to this postulation of Carpeni or with respect to the condensation products of the monomer. The dimolybdate anion Mo2Oj-k discarded as a product since it is only stable in nonaqueous solvents ( Day et al, 1977). It is believed that the heptameric anion M07024~ is the first product and that further condensation produces the octameric anion M0g026~ ( Cotton and Wilkinson, 1980).…”

Section: The Mo Sorption Reactionmentioning

confidence: 99%

Molybdate sorption by oxides of aluminium and iron

Ferreiro

Helmy

Bussetti

1985

J Plant Nutrition & Soil

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Summary -ZusammenfPssungThe sorption of molybdate by goethite, hematite, bayerite and a-AlzO3 was studied as a function of molybdate concentration and pH. The sorption isotherms exhibited double sorption plateaus in which the amount of Mo sorbed in the second plateau was double that in the first. This was attributed to the polymerization of molybdates as the concentration increases. Furthermore Mo sorption was found to be associated with a cosorption of Na cations, probably present to maintain electroneutrality in the surface zone.The sorption showed high sensitivity towards the pH, attaining a maximum at pH 4. For the iron oxides the decrease in sorption was much less pronounced on the acid side of the pH maximum and occured at lower pH values than that of the A1 oxides.Molybdate sorption is explained in terms of a ligand exchange reaction between molybdate and surface hydroxyls. Molybdaborption durch Al-und Fe-OxideDie Molybdatsorption durch Goethit, Hamatit, Bayerit und a-AlzO3 wurde als Funktion von Mo-Konzentration und pH untersucht. Die Austauschisothermen zeigten zwei Plateaus, von denen das zweite das doppelte des ersten ergab, was durch Polymerisation verursacht wurde. AuBerdem ging der Mo-Polymerisation eine Kosorption von Na einher. Die Sorption zeigte eine deutliche pH-Abhangigkeit mit einem Maximum bei pH 4. Die Mo-Sorption wird als Liganden-Austauschreaktion zwischen Molybdat und Hydroxylgruppen der Oberflache angesehen.

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“…This ion shows two strong absorptions in its IR spectrum, [30,31,32] at 783-795 and 880-885 cm À1 and corresponding to stretching of the bridging and terminal MoÀO bonds respectively. There is a further weak feature around 300 cm À1 , corresponding to a bending motion of, primarily, the terminal metalÀoxygen bonds.…”

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confidence: 99%

Computational Study of Solvent Effects and the Vibrational Spectra of Anderson Polyoxometalates

Bridgeman

2006

Chemistry A European J

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The structures and vibrational frequencies of the type II Anderson heteropolyanions [TeMo6O24]6- and [IMo6O24]5- have been calculated by using density functional theory using a number of common functionals and basis sets. For the first time, Raman intensities have been calculated and the effect of solvent on the modeling has been investigated. The calculated IR and Raman spectral traces are in good agreement with experiment allowing the characteristic group frequencies for this class of polyoxometalate to be identified. The stretching vibrations of the molybdenum-oxygen bonds are predicted to occur at somewhat lower frequencies than in the type I polyoxometalates. Stretching of the heteroatom-oxygen bonds occurs at significantly lower frequencies than in the Keggin anions as a simple consequence of the higher coordination number of the central heteroatom in the Anderson systems. For the [Mo2O7]2- and [Mo6O19]2- ions, the relatively low negative charge leads to small structural changes when solvent is included. In these systems, solvent leads to an increase in the bond polarity and a decrease in the covalent bond orders, resulting in decreases in the calculated frequencies. For the Anderson anions, the higher negative charges leads to greater solvent effects with contraction of the clusters and increases in the frequencies of bands due to stretching of the two, cis-related molybdenum-oxygen bonds.

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Synthesis and characterization of the dimolybdate ion, Mo2O72-

Cited by 85 publications

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Solid‐state ¹⁴N MAS NMR of ammonium ions as a spy to structural insights for ammonium salts

Solid‐state ¹⁴N MAS NMR of ammonium ions as a spy to structural insights for ammonium salts

Molybdate sorption by oxides of aluminium and iron

Computational Study of Solvent Effects and the Vibrational Spectra of Anderson Polyoxometalates

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Synthesis and characterization of the dimolybdate ion, Mo2O72-

Cited by 85 publications

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Solid‐state 14N MAS NMR of ammonium ions as a spy to structural insights for ammonium salts

Solid‐state 14N MAS NMR of ammonium ions as a spy to structural insights for ammonium salts

Molybdate sorption by oxides of aluminium and iron

Computational Study of Solvent Effects and the Vibrational Spectra of Anderson Polyoxometalates

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Solid‐state ¹⁴N MAS NMR of ammonium ions as a spy to structural insights for ammonium salts

Solid‐state ¹⁴N MAS NMR of ammonium ions as a spy to structural insights for ammonium salts