Geochemical kinetics via the Swift–Connick equations and solution NMR

Harley, Steven J.; Ohlin, C. André; Casey, William H.

doi:10.1016/j.gca.2011.04.009

Cited by 20 publications

(23 citation statements)

References 63 publications

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“…The NMR methods used to follow the exchange of isotopes or movement of mass into, and out of, the cluster are dominated by linebroadening approaches, [54][55][56][57][58] although there is no reason that selective-excitation methods cannot also be used. The NMR methods used to follow the exchange of isotopes or movement of mass into, and out of, the cluster are dominated by linebroadening approaches, [54][55][56][57][58] although there is no reason that selective-excitation methods cannot also be used.…”

Section: Isotope-exchange Dynamics: Nmr and Esi-msmentioning

confidence: 99%

An overview of selected current approaches to the characterization of aqueous inorganic clusters

et al. 2015

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This Perspective article highlights some of the traditional and non-traditional analytical tools that are presently used to characterize aqueous inorganic nanoscale clusters and polyoxometalate ions. The techniques discussed in this article include nuclear magnetic resonance spectroscopy (NMR), small angle X-ray scattering (SAXS), dynamic and phase analysis light scattering (DLS and PALS), Raman spectroscopy, and quantum mechanical computations (QMC). For each method we briefly describe how it functions and illustrate how these techniques are used to study cluster species in the solid state and in solution through several representative case studies. In addition to highlighting the utility of these techniques, we also discuss limitations of each approach and measures that can be applied to circumvent such limits as it pertains to aqueous inorganic cluster characterization.

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Section: Isotope-exchange Dynamics: Nmr and Esi-msmentioning

confidence: 99%

An overview of selected current approaches to the characterization of aqueous inorganic clusters

et al. 2015

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“…where Χ is the mole fraction of either the bound (b) or free (f) species. At the slow‐exchange limit (at which the measured signals continue to broaden with increased temperature), the Swift–Connick formalism describes the FWHM of the free signal by Equation :

true π (FWHM_{normalp} - FWHM_{normaln}) k_{ex, normalf} = k_{ex, normalb} X_{b} / X_{f}

…”

Section: Resultsmentioning

confidence: 99%

Rates of Ligand Exchange around the Bis‐Oxalato Complex [NpO₂(C₂O₄)₂]³⁻ Measured by Using Multinuclear NMR Spectroscopy under Neutral to Semi‐Alkaline Conditions

et al. 2018

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The kinetics of ligand exchange between the free oxalate ion, C2O42−, and the bis‐oxalato NpV complex, [NpO2(C2O4)2]3−, in aqueous solution are reported by using 13C and 17O NMR spectroscopy methods. Rates of exchange were measured in the pH regime of 6.5–9.0, at which speciation is shown to be suitably simple. Because the neptunium(V) complex is paramagnetic, the rates of ligand exchange were estimated by following the width of the 13C and 17O signals assigned to the free oxalate ion in solution and by applying the Swift–Connick method for measuring rates of exchange. A set of experiments were conducted in which pH and total oxalate concentration were varied, and the linear dependence of the rate on these parameters was demonstrated. Variable‐temperature NMR spectroscopy was also performed to measure activation parameters of complexation. At pH<8.0, ΔH≠=16.9 ±4.9 kJ mol−1 and ΔS≠=−116.3 ±17.1 kJ mol−1 K−1, whereas at pH>8.0 there is almost no dependence on temperature, which is interpreted to indicate that hydrolysis is coupled to ligand exchange under these conditions.

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“…While the former does not apply to coupled spin systems, its conceptual simplicity and applicability to uncoupled spin systems, such as is often effectively the case in 17 O NMR experiments, have made it a common approach in kinetic studies of solution dynamics of inorganic coordination compounds and discrete metal oxide clusters. As was made clear in a recent paper [4], even a cell phone now easily has enough power to run the software to simulate spectra via the Bloch-McConnell equations. Much of 17 O NMR applied to kinetics relies on this vector model of magnetic relaxation, leading to the Swift-Connick equations of solution chemistry.…”

Section: The Classical Vector Model Of Nuclear Magnetic Resonancementioning

confidence: 99%

17 O NMR as a Tool in Discrete Metal Oxide Cluster Chemistry

Ohlin

Casey

2018

Annual Reports on NMR Spectroscopy

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This chapter covers recent developments in 17 O NMR spectroscopy as applied to discrete metal oxide clusters, particularly in the context of their use as models in geochemistry and catalysis. Dynamic 17 O NMR methods based on the McConnell-Bloch equations are explored in depth, and recent advances are reviewed. High-pressure NMR methods are also discussed and reviewed, as are recent developments in the use of density functional theory in the computation of 17 O NMR shifts in polyoxometalates. The emphasis of the chapter is on the new developments that promise to reinvigorate 17 O NMR as a central tool in the study of aqueous chemical kinetics, with the most urgent challenges being understanding the rates of isotopic substitution into bridging oxygens in clusters.

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Geochemical kinetics via the Swift–Connick equations and solution NMR

Cited by 20 publications

References 63 publications

An overview of selected current approaches to the characterization of aqueous inorganic clusters

An overview of selected current approaches to the characterization of aqueous inorganic clusters

Rates of Ligand Exchange around the Bis‐Oxalato Complex [NpO₂(C₂O₄)₂]³⁻ Measured by Using Multinuclear NMR Spectroscopy under Neutral to Semi‐Alkaline Conditions

17 O NMR as a Tool in Discrete Metal Oxide Cluster Chemistry

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Geochemical kinetics via the Swift–Connick equations and solution NMR

Cited by 20 publications

References 63 publications

An overview of selected current approaches to the characterization of aqueous inorganic clusters

An overview of selected current approaches to the characterization of aqueous inorganic clusters

Rates of Ligand Exchange around the Bis‐Oxalato Complex [NpO2(C2O4)2]3− Measured by Using Multinuclear NMR Spectroscopy under Neutral to Semi‐Alkaline Conditions

17 O NMR as a Tool in Discrete Metal Oxide Cluster Chemistry

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Rates of Ligand Exchange around the Bis‐Oxalato Complex [NpO₂(C₂O₄)₂]³⁻ Measured by Using Multinuclear NMR Spectroscopy under Neutral to Semi‐Alkaline Conditions