A Definitive Example of Aluminum-27 Chemical Shielding Anisotropy

Schurko, Robert W.; Wasylishen, Roderick E.; Phillips, Andrew D.

doi:10.1006/jmre.1998.1460

Cited by 30 publications

(22 citation statements)

References 39 publications

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“…[43] These values are in excellent agreement with static 27 Al NMR data already reported in the literature. [70] It has to be noticed that η Q = 0: this result is actually not in contradiction with the crystallographic data, as Al-O-P = 176.0…”

Section: S100mentioning

confidence: 60%

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New perspectives in the PAW/GIPAW approach: JP-O-Si coupling constants, antisymmetric parts of shift tensors and NQR predictions

et al. 2010

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In 2001, Pickard and Mauri implemented the gauge including projected augmented wave (GIPAW) protocol for first-principles calculations of NMR parameters using periodic boundary conditions (chemical shift anisotropy and electric field gradient tensors). In this paper, three potentially interesting perspectives in connection with PAW/GIPAW in solid-state NMR and pure nuclear quadrupole resonance (NQR) are presented: (i) the calculation of J coupling tensors in inorganic solids; (ii) the calculation of the antisymmetric part of chemical shift tensors and (iii) the prediction of (14)N and (35)Cl pure NQR resonances including dynamics. We believe that these topics should open new insights in the combination of GIPAW, NMR/NQR crystallography, temperature effects and dynamics. Points (i), (ii) and (iii) will be illustrated by selected examples: (i) chemical shift tensors and heteronuclear (2)J(P-O-Si) coupling constants in the case of silicophosphates and calcium phosphates [Si(5)O(PO(4))(6), SiP(2)O(7) polymorphs and α-Ca(PO(3))(2)]; (ii) antisymmetric chemical shift tensors in cyclopropene derivatives, C(3)X(4) (X = H, Cl, F) and (iii) (14)N and (35)Cl NQR predictions in the case of RDX (C(3)H(6)N(6)O(6)), β-HMX (C(4)H(8)N(8)O(8)), α-NTO (C(2)H(2)N(4)O(3)) and AlOPCl(6). RDX, β-HMX and α-NTO are explosive compounds.

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Section: S100mentioning

confidence: 60%

“…The GIPAW data seem more accurate than 27 Al cluster calculations involving Hartree-Fock and B3LYP/DFT methods. [70,71] The |C Q | values for 35 Cl (Table 9) are very strong and characteristic for Cl atoms involved in covalent Al-Cl and P-Cl bonds. [21,72] As I = 3/2 for 35 Cl, a unique pure NQR resonance is expected at [21] :…”

Section: S100mentioning

confidence: 99%

New perspectives in the PAW/GIPAW approach: JP-O-Si coupling constants, antisymmetric parts of shift tensors and NQR predictions

et al. 2010

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“…In addition, the largest aluminum CS tensor spans measured in the solid state are only of the order of 100 ppm. [8,35,54,55] Acquisition of the spectra of both the CT and STs may be used to confirm the quadrupolar parameters and ascertain the minimal contribution of aluminum CSA to the overall spectral appearance. Since the QCPMG frequency-stepped method provides a higher S/N ratio than Hahn-echo experiments, low-resolution QCPMG spectra of the CT and STs were acquired for both compounds.…”

Section: Solid-state Nmr Spectroscopymentioning

confidence: 99%

Ultra‐wideline ²⁷Al NMR Investigation of Three‐ and Five‐Coordinate Aluminum Environments

et al. 2006

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Ultra-wideline 27Al NMR experiments are conducted on coordination compounds with 27Al nuclei possessing immense quadrupolar interactions that result from exceptionally nonspherical coordination environments. NMR spectra are acquired using a methodology involving frequency-stepped, piecewise acquisition of NMR spectra with Hahn-echo or quadrupolar Carr-Purcell Meiboom-Gill (QCPMG) pulse sequences, which is applicable to any half-integer quadrupolar nucleus with extremely broad NMR powder patterns. Despite the large breadth of these central transition powder patterns, ranging from 250 to 700 kHz, the total experimental times are an order of magnitude less than previously reported experiments on analogous complexes with smaller quadrupolar interactions. The complexes examined feature three- or five-coordinate aluminum sites: trismesitylaluminum (AlMes3), tris(bis(trimethylsilyl)amino)aluminum (Al(NTMS2)3), bis[dimethyl tetrahydrofurfuryloxide aluminum] ([Me2-Al(mu-OTHF)]2), and bis[diethyl tetrahydrofurfuryloxide aluminum] ([Et2-Al(mu-OTHF)]2). We report some of the largest 27Al quadrupolar coupling constants measured to date, with values of C(Q)(27Al) of 48.2(1), 36.3(1), 19.9(1), and 19.6(2) MHz for AlMes3, Al(NTMS2)3, [Me2-Al(mu-OTHF)]2, and [Et2-Al(mu-OTHF)]2, respectively. X-ray crystallographic data and theoretical (Hartree-Fock and DFT) calculations of 27Al electric field gradient (EFG) tensors are utilized to examine the relationships between the quadrupolar interactions and molecular structure; in particular, the origin of the immense quadrupolar interaction in the three-coordinate species is studied via analyses of molecular orbitals.

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“…The calculations also show that it is not surprising that the two-bond 2 J( 31 P, 27 Al) coupling constant, the only one which would be potentially accessible without isotopic enrichment in the 31 P and 27 Al SSNMR spectra of Cl 3 AlOPCl 3 , was not observed experimentally. [21,23] The calculated results converge toward a value close to zero (e.g. the highest level result (pcJ-3; 857 basis functions) is only 1.0 Hz).…”

Section: Resultsmentioning

confidence: 80%

“…[21,23] Presented in Table 1 27 Al) coupling constants for the various pcJ-n and aug-pcJ-n basis sets. The convergence behavior of the coupling constants with respect to basis set size is depicted in Fig.…”

Section: Resultsmentioning

confidence: 99%

A computational investigation of J couplings involving 27Al, 17O, and 31P

Bryce

2010

Magn. Reson. Chem.

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Indirect nuclear spin-spin (J) couplings between (31)P, (27)Al, and (17)O are computed for Cl(3)POAlCl(3), Ph(3)PO, Ph(3)PAlCl(3), Al(H(2)O)(6)(3+), an aluminophosphate model system, and grossite model systems, using the B3LYP hybrid functional and the pcJ-n and aug-pcJ-n basis sets. The results provide computational corroboration of the existence of J coupling constants between (31)P, (17)O, and (27)Al of suitable magnitude for INEPT-style experiments in which connectivity is established as a result of magnetization transfer using these couplings. Potentially useful correlations between structure (bond lengths, angles, dihedrals) and the coupling constants (1)J((27)Al, (17)O), (1)J((31)P, (17)O), and (2)J((31)P, (27)Al) are presented. Calculated values of near zero for both (1)J((27)Al, (17)O) and (2)J((31)P, (27)Al), depending on the molecule and the geometry, suggest that some structurally important correlations could be absent in NMR spectra which rely on magnetization transfers solely based on these isotropic coupling constants.

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A Definitive Example of Aluminum-27 Chemical Shielding Anisotropy

Cited by 30 publications

References 39 publications

New perspectives in the PAW/GIPAW approach: JP-O-Si coupling constants, antisymmetric parts of shift tensors and NQR predictions

New perspectives in the PAW/GIPAW approach: JP-O-Si coupling constants, antisymmetric parts of shift tensors and NQR predictions

Ultra‐wideline ²⁷Al NMR Investigation of Three‐ and Five‐Coordinate Aluminum Environments

A computational investigation of J couplings involving 27Al, 17O, and 31P

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A Definitive Example of Aluminum-27 Chemical Shielding Anisotropy

Cited by 30 publications

References 39 publications

New perspectives in the PAW/GIPAW approach: JP-O-Si coupling constants, antisymmetric parts of shift tensors and NQR predictions

New perspectives in the PAW/GIPAW approach: JP-O-Si coupling constants, antisymmetric parts of shift tensors and NQR predictions

Ultra‐wideline 27Al NMR Investigation of Three‐ and Five‐Coordinate Aluminum Environments

A computational investigation of J couplings involving 27Al, 17O, and 31P

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Ultra‐wideline ²⁷Al NMR Investigation of Three‐ and Five‐Coordinate Aluminum Environments