Theoretical study on <sup>19</sup>F magnetic shielding constants of some metal fluorides

Cai, Shuhui; Yu, Xianyong; Zhong, Cheng; Wan, Huilin

doi:10.1002/mrc.1274

Cited by 15 publications

(19 citation statements)

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“…Some early computational work (aimed at benchmarking and validation) included F 2 as test molecule, which proved to be challenging [26][27][28]. Interest in modeling 19 F shifts has steadily continued, and several papers have appeared in the last decade aimed at general structural issues, solution chemistry and physical organic chemistry, [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46] solid-state issues (especially the prediction of chemical shift tensors), [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64] J-couplings [65][66][67][68][69][70][71][72]…”

Section: Introductionmentioning

confidence: 99%

Computational 19F NMR. 1. General features

2012

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Fluorine-19 NMR chemical shifts have been calculated for a wide variety of fluorine-containing inorganic and organic molecules by relativistic DFT methods. The agreement with experimental values, spanning the whole range from ClF to FOOF, is satisfactory but somewhat less accurate than for comparable light nuclei. 19 F shifts in uranium chlorofluorides have been analyzed in detail, and the poor agreement with experiment is partly rationalized.

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Section: Introductionmentioning

confidence: 99%

Computational 19F NMR. 1. General features

2012

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“…Using GAUSSIAN 94 and 98 10 packages, satisfactory results were obtained for fluorine-containing molecules, [11][12][13] for fluoride crystalline compounds, [14][15][16][17][18][19][20] and even for glassy phases. 20 In these latter studies, non-embedded cluster models were used to mimic the crystal structure.…”

Section: Introductionmentioning

confidence: 82%

“…8,[15][16][17][18] To be consistent with our previous experimental results, R-Na 3 AlF 6 and Na 5 Al 3 F 14 compounds were specially synthesized by us 23 and the 19 F NMR spectra were recorded using high-speed MAS NMR technique at various spinning rates and numerically reconstructed. For R-Na 3 AlF 6 , a single NMR line is measured at -22 ppm, which is consistent with previous studies.…”

Section: Computationalmentioning

confidence: 98%

Cluster Models and ab Initio Calculations of ¹⁹F NMR Isotropic Chemical Shifts for Inorganic Fluorides

et al. 2005

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(19)F NMR isotropic chemical shift (delta(iso)) calculations are performed in crystallized compounds using the GIAO method with the B3LYP hybrid functional at DFT level. Clusters centered on the studied fluorine atoms mimic the crystalline structures. The 6-311+G(d) basis set is chosen for the central fluorine atom, and the LanL2DZ basis set for the others. The metal atoms are described by the 3-21G(2d) basis set or, when not available, by the CRENBL basis set with the corresponding ECP, and augmented with 2d polarization functions when existing. First, for high-symmetry systems (MF, MF(2), and MF(3) compounds), a systematization of the cluster building up from coordination spheres is proposed, generalized to fluoroperovskites and fluoroaluminates KAlF(4) and RbAlF(4). When applied to rather low symmetry systems such as barium fluorometalates BaMgF(4), BaZnF(4), and Ba(2)ZnF(6), the definition of the coordination spheres is far from easy. Then, for structures built up from a MF(6) octahedron network, we may define different "starting clusters": [FM(2)F(8)] for the shared fluorine atoms, [FMF(4)] for the unshared ones, and [FBa(4)](7+) for the "free" ones. Analogous "starting clusters" are then tested on compounds from the NaF-AlF(3), BaF(2)-AlF(3), and CaF(2)-AlF(3) binary systems and for alpha-BaCaAlF(7) that are also built up from a MF(6) octahedron network. For each of these corresponding fluorine sites, delta(iso) values are calculated with the "starting clusters" and several larger clusters and compared to the experimental delta(iso) values. For the barium-containing clusters, the RMS deviation is equal to 51 ppm. It is suggested that this result may be related to the poor quality of the barium basis sets for which no polarization functions are available for the moment. In total, chemical shifts were calculated for 122 fluorine sites, in a various range of compounds. For the clusters without barium, the ab initio method leads to a RMS equal to 22 ppm, which is a quite nice result keeping in mind that the (19)F chemical shift range is larger than 200 ppm.

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“…Solid-state 19 F NMR was used to provide a reference for quantum mechanical calculation of the chemical shifts in fluorides [30], whereas EPR studies have been focused on characterisation of properties and the coordination sphere of paramagnetic ions in the lattice [31,32]. Only one study uses paramagnetic Mn 2+ as a probe doped in a BaMgF 4 matrix [33].…”

Section: Introductionmentioning

confidence: 99%

A variable temperature solid-state nuclear magnetic resonance, electron paramagnetic resonance and Raman scattering study of molecular dynamics in ferroelectric fluorides

Kowalczyk¹,

Kemp²,

Walker³

et al. 2011

J. Phys.: Condens. Matter

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The local nuclear and electronic structures and molecular dynamics of the ferroelectric lattice in selected geometric fluorides (BaMgF 4 , BaZnF 4 , BaMg 1−x Mn x F 4 and BaMg 1−x Ni x F 4 ; x = 0.001 and 0.005) have been investigated. The 19 F and 25 Mg isotropic chemical shift δ iso , 25 Mg quadrupolar coupling constants (C q ) and asymmetry parameters (η) reflect the geometry of the coordination spheres. The zero-field splitting parameters |D| and |E| are consistent with distorted axial symmetry (low temperatures) and nearly rhombic symmetry (high temperatures) of octahedral Mn 2+ coordination. The high resolution of the nuclear magnetic resonance, electron paramagnetic resonance and phonon spectra are consistent with the highly ordered crystallographic structure. Combined multi-technique data evidence the subtle discontinuous changes in the temperature dependences of |D| and |E|, isotropic chemical shifts δ iso and signature parameters of Raman bands and suggest a discontinuous structural distortion of the fluoride octahedra. The temperature at which this change occurs depends on the ionic radius of the central ion of the octahedral site and is estimated to be ∼300 K for Zn 2+ fluorides and ∼240 K for Mg 2+ fluorides. This geometrical distortion modifies the lattice dynamics and originates from the rotation of the fluoride octahedra around a new direction approximately perpendicular to that related to the paraelectric-ferroelectric phase transition.

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Theoretical study on ¹⁹F magnetic shielding constants of some metal fluorides

Cited by 15 publications

References 37 publications

Computational 19F NMR. 1. General features

Computational 19F NMR. 1. General features

Cluster Models and ab Initio Calculations of ¹⁹F NMR Isotropic Chemical Shifts for Inorganic Fluorides

A variable temperature solid-state nuclear magnetic resonance, electron paramagnetic resonance and Raman scattering study of molecular dynamics in ferroelectric fluorides

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Theoretical study on 19F magnetic shielding constants of some metal fluorides

Cited by 15 publications

References 37 publications

Computational 19F NMR. 1. General features

Computational 19F NMR. 1. General features

Cluster Models and ab Initio Calculations of 19F NMR Isotropic Chemical Shifts for Inorganic Fluorides

A variable temperature solid-state nuclear magnetic resonance, electron paramagnetic resonance and Raman scattering study of molecular dynamics in ferroelectric fluorides

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Theoretical study on ¹⁹F magnetic shielding constants of some metal fluorides

Cluster Models and ab Initio Calculations of ¹⁹F NMR Isotropic Chemical Shifts for Inorganic Fluorides