Two-dimensional NMR measurement and point dipole model prediction of paramagnetic shift tensors in solids

Walder, Brennan J.; Dey, Krishna Kishor; Davis, Michael C.; Baltisberger, Jay H.; Grandinetti, Philip J.

doi:10.1063/1.4904548

Cited by 25 publications

(22 citation statements)

References 98 publications

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“…Recent advances in NMR methodology have facilitated the acquisition of high-resolution SSNMR spectra by fast magic-angle spinning (MAS) [6][7][8][9] and NMR pulse sequences for paramagnetic systems [10][11][12][13][14][15]. However, the analysis of paramagnetic NMR (pNMR) spectra is much more complicated than for their diamagnetic analogues due to the large magnetic moments of the unpaired electrons.…”

Section: Introductionmentioning

confidence: 99%

Assignment of solid-state 13C and 1H NMR spectra of paramagnetic Ni(II) acetylacetonate complexes aided by first-principles computations

Rouf

Jakobsen

Mareš

et al. 2017

Solid State Nuclear Magnetic Resonance

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Recent advances in computational methodology allowed for first-principles calculations of the nuclear shielding tensor for a series of paramagnetic nickel(II) acetylacetonate complexes, [Ni(acac)L] with L = HO, DO, NH, ND, and PMePh have provided detailed insight into the origin of the paramagnetic contributions to the total shift tensor. This was employed for the assignment of the solid-state H andC MAS NMR spectra of these compounds. The two major contributions to the isotropic shifts are by orbital (diamagnetic-like) and contact mechanism. The orbital shielding, contact, as well as dipolar terms all contribute to the anisotropic component. The calculations suggest reassignment of the C methyl and carbonyl resonances in the acac ligand [Inorg. Chem.53, 2014, 399] leading to isotropic paramagnetic shifts of δ(C) ≈ 800-1100 ppm and ≈180-300 ppm for C for the methyl and carbonyl carbons located three and two bonds away from the paramagnetic Ni(II) ion, respectively. Assignment using three different empirical correlations, i.e., paramagnetic shifts, shift anisotropy, and relaxation (T) were ambiguous, however the latter two support the computational results. Thus, solid-state NMR spectroscopy in combination with modern quantum-chemical calculations of paramagnetic shifts constitutes a promising tool for structural investigations of metal complexes and materials.

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Section: Introductionmentioning

confidence: 99%

Assignment of solid-state 13C and 1H NMR spectra of paramagnetic Ni(II) acetylacetonate complexes aided by first-principles computations

Rouf

Jakobsen

Mareš

et al. 2017

Solid State Nuclear Magnetic Resonance

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“…Agreement with the nucleicentered point dipole model is improved when the unpaired spin density is additionally delocalized onto the two oxygen ligands, yielding the correct sign of the paramagnetic shift anisotropy and closer agreement with the measured tensor orientation. Nearly perfect agreement within the uncertainty of their measurement, however, is found with a model with point dipoles displaced away from the nuclei and at positions consistent with the maximum electron density of the lobes of the singly occupied anti-bonding molecular orbital (Walder et al, 2015). Not only does this model yield excellent agreement, but it results in fractional delocalization of 13.3% onto the two closest chlorides and 1.6% onto the two closest oxygen ligands, a finding that is more consistent with results obtained from electron paramagnetic resonance and magnetic neutron scattering experiments on this system.…”

Section: General Theorymentioning

confidence: 82%

“…Grandinetti et al that also enhances sensitivity and eliminates artifacts (Walder et al, 2015). They demonstrate the utility of these pulse sequences in obtaining accurate parameters for the 2 H paramagnetic shift and quadrupolar coupling tensors for the model compound CuCl2  2D2O.…”

Section: General Theorymentioning

confidence: 93%

Recent Advances in Theoretical and Physical Aspects of NMR Chemical Shifts

Dios

Jameson

2015

KIMIKA

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In the first part of this review, theoretical aspects of nuclear magnetic shielding include (a) general theory, for example, newly developed approaches in relativistic theory of nuclear shielding, the relation between the spin-rotation tensor and shielding in relativistic theory, ab initio methods for treating open shell systems and a complete theory of chemical shifts in paramagnetic systems, the link between the definitions of the elusive concepts aromaticity and anti-aromaticity and the magnetic properties: the magnetizability tensor and the nuclear magnetic shielding tensor via delocalized electron currents and electron current maps, (b) ab initio and DFT calculations, both relativistic and non-relativistic, for various nuclei in various molecular systems using various levels of theoretical treatment. Physical aspects include (a) anisotropy of the shielding tensor, usually from solid state measurements, and calculations to support these, (b) shielding surfaces and rovibrational averaging, paying special attention to the sensitive relationship between shielding and bond angles or torsion angles that makes shielding such a powerful tool for structural/conformational determination in macromolecules, (c) chemical shifts that arise from isotopic substitution of NMR nucleus or neighboring nuclei, (d) intermolecular effects on nuclear shielding, and (e) absolute shielding scales.

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“…Both the limitations of the inhomogeneous BMS broadening and the spectral window in 1 can be addressed via a double shearing transformation similar to the scheme proposed in for TOP, [36][37][38]41,42] pure shift NMR in solution, [43] and COASTER. [35] After this transformation, a new (t ′ 1 , t ′ 2 ) two-dimensional time-domain system where the frequency terms that depend on p do not evolve in t ′ 1 is constructed, which eliminates the BMS broadening and shift in ′ 1 , and instead transfers them to ′ 2 where we can benefit from the large spectral window of directly acquired dimension, analogously to TOP processing [36][37][38] as demonstrated by Walder et al [41] and Paruzzo et al [42] In this time-domain system, C (4) is refocused along t ′ 2 , and, consequentially, the indirect dimension accomodates the Rank 4 second-order quadrupolar-induced anisotropy, which is usually sufficiently small to be represented within the limited spectral window. Furthermore, it is worth noting that this double shear transformation is done entirely via passive transformations, which do not require any undesirable interpolation of data, and are carried out on the full t 1 − t 2 quadrant system, generated via TOP processing, thus avoiding possible folding artefacts introduced by the shear transformations.…”

Section: Double Sheared Top-mqmas/stmasmentioning

confidence: 99%

Separation of quadrupolar and paramagnetic shift interactions with TOP‐STMAS/MQMAS in solid‐state lighting phosphors

Carvalho

Jaworski

Brady

et al. 2020

Magnetic Reson in Chemistry

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A new approach for processing satellite-transition magic-angle spinning (STMAS) and multiple-quantum magic-angle spinning (MQMAS) data, based on the two-dimensional one-pulse (TOP) method, which separates the second-rank quadrupolar anisotropy and paramagnetic shift interactions via a double shearing transformation, is described. This method is particularly relevant in paramagnetic systems, where substantial inhomogeneous broadening may broaden the lineshapes. Furthermore, it possesses an advantage over the conventional processing of MQMAS and STMAS spectra because it overcomes the limitation on the spectral width in the indirect dimension imposed by rotor synchronization of the sampling interval. This method was applied experimentally to the 27 Al solid-state nuclear magnetic resonance of a series of yttrium aluminum garnets (YAGs) doped with different lanthanide ions, from which the quadrupolar parameters of paramagnetically shifted and bulk unshifted sites were extracted. These parameters were then compared with density functional theory calculations, which permitted a better understanding of the local structure of Ln substituent ions in the YAG lattice.

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Two-dimensional NMR measurement and point dipole model prediction of paramagnetic shift tensors in solids

Abstract: A new two-dimensional NMR experiment to separate and correlate the first-order quadrupolar and chemical/paramagnetic shift interactions is described. This experiment, which we call the shifting-d echo experiment, allows a more precise deter-

Cited by 25 publications

References 98 publications

Assignment of solid-state 13C and 1H NMR spectra of paramagnetic Ni(II) acetylacetonate complexes aided by first-principles computations

Assignment of solid-state 13C and 1H NMR spectra of paramagnetic Ni(II) acetylacetonate complexes aided by first-principles computations

Recent Advances in Theoretical and Physical Aspects of NMR Chemical Shifts

Separation of quadrupolar and paramagnetic shift interactions with TOP‐STMAS/MQMAS in solid‐state lighting phosphors

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