NMR and EPR spectroscopies and electron density distribution in polyoxoanions

Kazansky, Leonid P.; McGarvey, Bruce R.

doi:10.1016/s0010-8545(98)00244-6

Cited by 35 publications

(28 citation statements)

References 84 publications

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“…The remaining part is distributed over 5 d

_{z^{2}}

( c 2 ) and the ligands. These values are in agreement with those previously found for other transition‐metal ions such as W, Mo, or V hosted in Keggin structures 66…”

Section: Resultssupporting

confidence: 92%

Functionalization of Heteropolyanions—Osmium and Rhenium Nitrido Derivatives of Keggin‐ and Dawson‐Type Polyoxotungstates: Synthesis, Characterization and Multinuclear (¹⁸³W, ¹⁵N) NMR, EPR, IR, and UV/Vis Fingerprints

Dablemont

Hamaker

Thouvenot

et al. 2006

Chemistry A European J

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Reaction of K(10)[alpha(2)-P(2)W(17)O(61)] or K(10)[alpha(1)-P(2)W(17)O(61)] or [Bu(4)N][OsCl(4)N] in a water/methanol mixture, and subsequent precipitation with (Bu(4)N)Br provided [alpha(2)-P(2)W(17)O(61){Os(VI)N}](7-) and [alpha(1)-P(2)W(17)O(61){Os(VI)N}](7-) Dawson structures as tetrabutylammonium salts. Reactions of [(Bu(4)N)(4)][alpha-H(3)PW(11)O(39)] with either [ReCl(3)(N(2)Ph(2))(PPh(3))(2)] or [Bu(4)N][ReCl(4)N] are alternatives to the synthesis of [(Bu(4)N)(4)][alpha-PW(11)O(39){Re(VI)N}]. (183)W and (15)N NMR, EPR, IR, and UV-visible spectroscopies and cyclic voltammetry have been used to characterize these compounds and the corresponding [(Bu(4)N)(4)][alpha-PW(11)O(39){Os(VI)N}] Keggin derivative.

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“…The remaining part is distributed over 5 d

_{z^{2}}

( c 2 ) and the ligands. These values are in agreement with those previously found for other transition‐metal ions such as W, Mo, or V hosted in Keggin structures 66…”

Section: Resultssupporting

confidence: 92%

Functionalization of Heteropolyanions—Osmium and Rhenium Nitrido Derivatives of Keggin‐ and Dawson‐Type Polyoxotungstates: Synthesis, Characterization and Multinuclear (¹⁸³W, ¹⁵N) NMR, EPR, IR, and UV/Vis Fingerprints

Dablemont

Hamaker

Thouvenot

et al. 2006

Chemistry A European J

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“…They could not be deconvoluted using a single resonance, in agreement with the crystal structure that contains two types of molybdenum environments: 6 Mo of the two trimeric caps and 12 Mo of the belt. Note that the two sites in solution spectrum were not resolved enough to be distinguished because of the quadrupolar coupling broadening . With prior knowledge of existence of these two sites in 1 : 2 ratio and imposing the same parameters in both the MAS and static NMR spectra, a reasonable possible solution for spectral deconvolution is proposed: line 1 ( C Q = 4.8 MHz, η Q = 0.8) accounts for 68% of the total spectrum intensity and is thus assigned to molybdenum from the belt; line 2 ( C Q = 3.5 MHz, η Q = 0.8) would correspond to the molybdenum atoms from the trimeric caps.…”

Section: Resultsmentioning

confidence: 94%

High‐field⁹⁵Mo and¹⁸³W static and MAS NMR study of polyoxometalates

Haouas

Trébosc

Roch‐Marchal

et al. 2017

Magnetic Reson in Chemistry

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The potential of high-field NMR to measure solid-state Mo and W NMR in polyoxometalates (POMs) is explored using some archetypical structures like Lindqvist, Keggin and Dawson as model compounds that are well characterized in solution. NMR spectra in static and under magic angle spinning (MAS) were obtained, and their analysis allowed extraction of the NMR parameters, including chemical shift anisotropy and quadrupolar coupling parameters. Despite the inherent difficulties of measurement in solid state of these low-gamma NMR nuclei, due mainly to the low spectral resolution and poor signal-to-noise ratio, the observed global trends compare well with the solution-state NMR data. This would open an avenue for application of solid-state NMR to POMs, especially when liquid-state NMR is not possible, e.g., for poorly soluble or unstable compounds in solution, and for giant molecules with slow tumbling motion. This is the case of Keplerate where we provide here the first NMR characterization of this class of POMs in the solid state. Copyright © 2017 John Wiley & Sons, Ltd.

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“…13 The first calculations were made for the high-and low-spin configurations under the T d group restrictions. In full agreement with all of the experimental determinations, which identify Co III W 12 as a high-spin complex, 38 the electronic configuration with S ) 2 was computed to be more stable than the configuration with four electrons in the orbital of symmetry e, but the energy difference between the two configurations may be considered relatively small, 0.51 eV.…”

Section: Methodsmentioning

confidence: 99%

Electronic and Magnetic Properties of α-Keggin Anions: A DFT Study of [XM₁₂O₄₀]ⁿ^-, (M = W, Mo; X = Al^III, Si^IV, P^V, Fe^III, Co^II, Co^III ) and [SiM₁₁VO₄₀]^m^- (M = Mo and W)

et al. 2001

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Calculations based on density functional theory (DFT) have been carried out to investigate the electronic and magnetic properties of the alpha-Keggin anions mentioned in the title. The atomic populations and the distribution of the electron density computed for the studied clusters support the hypothesis that an oxidized Keggin anion is an XO(4)(n-) clathrate inside a neutral M(12)O(36) cage. The energy gap between the band of occupied orbitals, formally delocalized over the oxo ligands, and the unoccupied d-metal orbitals, delocalized over the addenda, has been found to be independent of the central ion. However, substitution of a W or a Mo by V modifies the relative energy of the LUMO and then induces important changes in the redox properties of the cluster. In agreement with the most recent X-ray determination of [Co(III)W(12)O(40)](5-) and with the simplicity of the (183)W NMR and (17)O NMR spectra observed for this anion the calculations suggest that [Co(III)W(12)O(40)](5-) has a slightly distorted T(d ) geometry. For the parent cluster [CoW(12)O(40)](6-) the quadruplet corresponding to the anion encapsulating a Co(II) was found to be approximately 1 eV more stable than the species formed by a Co(III) and 1 e delocalized over the sphere of tungstens. The one-electron reduction of [Co(II)W(12)O(40)](6-) and [Fe(III)W(12)O(40)](5-) leads to the formation of the 1 e blue species [Co(II)W(12)O(40)](7-) and [Fe(III)W(12)O(40)](6-). The blue-iron cluster is considerably antiferromagnetic, and in full agreement with this behavior the low-spin state computed via a Broken Symmetry approach is 196 cm(-1) lower than the high-spin solution. In contrast, the cobalt blue anion has a low ferromagnetic coupling with an S-T energy gap of +20 cm(-1). This blue species is more stable than the alternative reduction product [Co(I)W(12)O(40)](7-) by more than 0.7 eV.

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NMR and EPR spectroscopies and electron density distribution in polyoxoanions

Cited by 35 publications

References 84 publications

Functionalization of Heteropolyanions—Osmium and Rhenium Nitrido Derivatives of Keggin‐ and Dawson‐Type Polyoxotungstates: Synthesis, Characterization and Multinuclear (¹⁸³W, ¹⁵N) NMR, EPR, IR, and UV/Vis Fingerprints

Functionalization of Heteropolyanions—Osmium and Rhenium Nitrido Derivatives of Keggin‐ and Dawson‐Type Polyoxotungstates: Synthesis, Characterization and Multinuclear (¹⁸³W, ¹⁵N) NMR, EPR, IR, and UV/Vis Fingerprints

High‐field⁹⁵Mo and¹⁸³W static and MAS NMR study of polyoxometalates

Electronic and Magnetic Properties of α-Keggin Anions: A DFT Study of [XM₁₂O₄₀]ⁿ^-, (M = W, Mo; X = Al^III, Si^IV, P^V, Fe^III, Co^II, Co^III ) and [SiM₁₁VO₄₀]^m^- (M = Mo and W)

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NMR and EPR spectroscopies and electron density distribution in polyoxoanions

Cited by 35 publications

References 84 publications

Functionalization of Heteropolyanions—Osmium and Rhenium Nitrido Derivatives of Keggin‐ and Dawson‐Type Polyoxotungstates: Synthesis, Characterization and Multinuclear (183W, 15N) NMR, EPR, IR, and UV/Vis Fingerprints

Functionalization of Heteropolyanions—Osmium and Rhenium Nitrido Derivatives of Keggin‐ and Dawson‐Type Polyoxotungstates: Synthesis, Characterization and Multinuclear (183W, 15N) NMR, EPR, IR, and UV/Vis Fingerprints

High‐field95Mo and183W static and MAS NMR study of polyoxometalates

Electronic and Magnetic Properties of α-Keggin Anions: A DFT Study of [XM12O40]n-, (M = W, Mo; X = AlIII, SiIV, PV, FeIII, CoII, CoIII ) and [SiM11VO40]m- (M = Mo and W)

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Functionalization of Heteropolyanions—Osmium and Rhenium Nitrido Derivatives of Keggin‐ and Dawson‐Type Polyoxotungstates: Synthesis, Characterization and Multinuclear (¹⁸³W, ¹⁵N) NMR, EPR, IR, and UV/Vis Fingerprints

Functionalization of Heteropolyanions—Osmium and Rhenium Nitrido Derivatives of Keggin‐ and Dawson‐Type Polyoxotungstates: Synthesis, Characterization and Multinuclear (¹⁸³W, ¹⁵N) NMR, EPR, IR, and UV/Vis Fingerprints

High‐field⁹⁵Mo and¹⁸³W static and MAS NMR study of polyoxometalates

Electronic and Magnetic Properties of α-Keggin Anions: A DFT Study of [XM₁₂O₄₀]ⁿ^-, (M = W, Mo; X = Al^III, Si^IV, P^V, Fe^III, Co^II, Co^III ) and [SiM₁₁VO₄₀]^m^- (M = Mo and W)