Towards higher resolution for quadrupolar nuclei in solid state NMR at very high field

Massiot, Dominique; Montouillout, V.; Magnenet, C.; Bessada, Catherine; Coutures, Jean-Pierre; Förster, Hans; Steuernagel, Stefan; Mueller, D.

doi:10.1016/s1387-1609(99)80074-7

Cited by 13 publications

(13 citation statements)

References 9 publications

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“…Solid-state 27 Al NMR experiments are able to provide information on the isotropic chemical shifts, quadrupolar coupling constants, and asymmetry parameters, as well as anisotropic chemical shift parameters (in certain cases). However, in some cases where resolution is compromised by overlapping spectral patterns, the use of multiple quantum MAS (MQMAS) experiments (100) or high magnetic fields (97,101) is advantageous. The 27 Al chemical shift and quadrupolar interactions are very sensitive to variation in geometry, ligands, and coordination number.…”

Section: Al Efg Tensorsmentioning

confidence: 99%

Analysis of electric field gradient tensors at quadrupolar nuclei in common structural motifs

Autschbach¹,

Zheng²,

Schurko³

2010

Concepts Magnetic Resonance

163

259

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ABSTRACT:This article is concerned with the analysis of electric field gradients (EFGs) using first-principles theory along with model calculations. Simple atomic orbital (AO) models for the EFG are developed in the spirit of the Townes-Dailey (TD) analysis and applied to various sets of sp n hybrid orbitals and to atomic d orbital shells. These AO models are then combined with modern analysis methods rooted in first principles theory which provide accurate localized molecular orbital contributions to the EFG. It is shown by density functional computations how such analyses of the EFG for a variety of typical structural motifs can provide an intuitive way of understanding the chemical origin of the magnitude and the sign of EFG tensors at atomic nuclei, as well as of their orientation with respect to the molecular coordinate frame. The utility of graphical visualizations of EFG tensors is also emphasized. The systems that are investigated span the range from very small molecules (carbon and sulfur EFGs in CO, CS, OCS) to small-and medium-sized molecules (nitrogen and aluminum EFGs in ammonia, methyl-cyanide and -isocyanide, aluminum AlX 3 model systems and various alumino-organic systems), to the metal atom field gradient in transition metal complexes with Ru and Nb and a variety of ligands.

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Section: Al Efg Tensorsmentioning

confidence: 99%

Analysis of electric field gradient tensors at quadrupolar nuclei in common structural motifs

Autschbach¹,

Zheng²,

Schurko³

2010

Concepts Magnetic Resonance

163

259

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“…From this observation it becomes possible to show that the Q 4 (3Al) site (main resonance of the T 2 group) is mostly coupled to a neighboring 29 Si T 2 for which larger bond angles are expected. Obtaining complementary structural information from 27 Al NMR experiments is more complicated, since the simple MAS 1D spectrum does not allow separation of different lines, even at high magnetic field [91,92]. In such a case the spin counting experiment [17] allows characterizing the connectivity of 27 Al atoms with neighboring 29 Si by generating various multiple quantum coherence order through the evolution under the 27 Al-O-29 Si 2 J scalar couplings.…”

Section: And T 2 Sitesmentioning

confidence: 99%

Detection and use of small J couplings in solid state NMR experiments

Massiot

Fayon

Deschamps

et al. 2009

Comptes Rendus. Chimie

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Over the years, solid-state nuclear magnetic resonance (NMR) spectroscopy has become an important tool for materials science, with its local point of view that is highly complementary to the structural information provided by diffraction techniques, electron microscopy, and molecular modeling, for example. As compared to other interactions that determine the spectral expression of the local structure of the observed nuclei in solid-state NMR experiments, the J coupling, characteristic of the chemical bonds, has received far less attention because of its being generally so small that it is masked in the line-widths. Nevertheless, the scalar or isotropic part of J couplings, which is not averaged by magic angle spinning (MAS), can be evidenced in many systems, and exploited to unequivocally characterize the extended coordination sphere. In a first step we describe the different experiments that permit the observation and the measurement of J couplings, even when dealing with quadrupolar nuclei. We then present new and recently-published results that illustrate the state of the art of NMR methodologies based on or intended for measuring J couplings in solids and the novel perspectives that they open towards better understanding of ordered and disordered materials at the subnanometric scale, a length scale that is otherwise difficult to access.

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“…The quadrupolar interaction scales indeed inversely proportional to the applied magnetic field so is reduced at higher fields. 25 In the area of B[III] sites, the spectrum recorded at 18.8 T shows two signals at 27 ppm (C Q = 2.7 MHz, η = 0.1) and 31 ppm (C Q = 2.9 MHz, η = 0.1) that can be attributed to BN 3 and BN 2 H sites, respectively, by comparison with previously obtained results on POL( ) 10 (Fig. 4(c)).…”

Section: B Nmr Studymentioning

confidence: 99%

11B and 15N solid state NMR investigation of a boron nitride preceramic polymer prepared by ammonolysis of borazine

Gervais

Framery

Duriez

et al. 2005

Journal of the European Ceramic Society

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Towards higher resolution for quadrupolar nuclei in solid state NMR at very high field

Cited by 13 publications

References 9 publications

Analysis of electric field gradient tensors at quadrupolar nuclei in common structural motifs

Analysis of electric field gradient tensors at quadrupolar nuclei in common structural motifs

Detection and use of small J couplings in solid state NMR experiments

11B and 15N solid state NMR investigation of a boron nitride preceramic polymer prepared by ammonolysis of borazine

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