51V and 93Nb high resolution NMR study of NbVO5

1991 ◽  
Vol 6 (2) ◽  
pp. 393-400 ◽  
Author(s):  
J. Davis ◽  
D. Tinet ◽  
J.J. Fripiat ◽  
J.M. Amarilla ◽  
B. Casal ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Chemical Shift Anisotropy ◽  
Quadrupole Coupling Constant ◽  
Isotropic Chemical Shift ◽  
Coupling Constant ◽  
Nmr Study ◽  
Resonance Frequencies ◽  
Quadrupole Coupling ◽  
High Resolution Nmr ◽  
Lower Electric Field

NbVO5 is characterized by 51V and 93Nb NMR resonance frequencies strongly upfield shifted when compared to those in model compounds V2O5 and LiNbO3. The chemical shift anisotropy dominates the 51V observed spectrum in a magnetic field of 11.7 T. The asymmetry parameter ηc is 0.2 and the quadrupole coupling constant is relatively small (1 MHz). The quadrupolar Hamiltonian overwhelmingly dominates the 93Nb spectrum (ηQ = 0.9) and the quadrupole coupling constant is huge (16.5 MHz). In agreement with the structure obtained from the x-ray powder diagram the isotropic chemical shift of 51V suggests that NbVO5 is indeed an orthovanadate. Interestingly, in NbVO5 the isotropic chemical shift of 93Nb reveals a better shielding of the 93Nb nucleus and a lower electric field gradient than in LiNbO3. Nb octahedra in NbVO5 are sharing corners whereas they share edges in LiNbO3.

The 59Co nuclear magnetic resonance spectra of polycrystalline complexes

1987 ◽  
Vol 65 (6) ◽  
pp. 1332-1335 ◽  
Author(s):  
Donald R. Eaton ◽  
Richard J. Buist ◽  
Brian G. Sayer
Keyword(s):  
Chemical Shift ◽  
Chemical Shift Anisotropy ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
X Ray ◽  
Low Field ◽  
Nmr Data ◽  
Nuclear Magnetic Resonance Spectra ◽  
Quadrupole Coupling ◽  
Low Field Nmr

The solid state 59Co nmr spectra of a number of octahedral complexes are reported. In the case of sodium hexanitrocobaltate(III) the spectra have been obtained at several different field strengths and the results are analysed to give a quadrupole coupling constant of 9.4 MHz, an asymmetry parameter of zero and an axial chemical shift tensor with an anisotropy of 180 ppm. Several other complexes have been examined at high field (11.8 T) to minimize the effects of quadrupole coupling and maximize the influence of chemical shift anisotropy. The results are, where possible, compared with single crystal X-ray and low field nmr data. It is concluded that high fields are necessary to obtain reliable chemical shift anisotropy values. The conditions necessary for obtaining reasonable quality spectra from polycrystalline samples containing quadrupolar nuclei are discussed.

35Cl AND 37Cl MAGNETIC RESONANCE OF SIMPLE CHLORINE COMPOUNDS

1965 ◽  
Vol 43 (9) ◽  
pp. 2530-2534 ◽  
Author(s):  
Yasukazu Saito
Keyword(s):  
Chemical Shift ◽  
Chemical Shifts ◽  
Quadrupole Coupling Constant ◽  
Coupling Constants ◽  
Coupling Constant ◽  
Reference Compound ◽  
Excitation Energies ◽  
Structural Applications ◽  
Quadrupole Coupling ◽  
Magnetic Resonances

The nuclear magnetic resonances of 35Cl and 37Cl in a number of simple chlorine compounds were measured. Since both the paramagnetic contribution for chemical shift and the quadrupole coupling constant of the atom are determined by the same radial distribution of the electron, a linear relationship between the chemical shifts and the quadrupole coupling constants may be expected for compounds for which the electronic excitation energies are comparable. This was demonstrated for the series of chloro-substituted methanes. By graphical extrapolation the absolute chemical shift of the reference compound, NaCl aqueous solution, was obtained. The chemical shift of Cl− aq. ion can be interpreted as the sum of the diamagnetic shift of Cl− spherical ion and a paramagnetic shift resulting from its hydration. The experimental and theoretical values of the paramagnetic chemical shift of the Cl2 molecule were −2.06 × 10−3 and −2.17 × 10−3, respectively. Paramagnetic chemical shifts and line widths of resonance spectra of simple chlorine compounds are discussed, as well as the feasibility of high-resolution chlorine resonances for structural applications.

A solid-state 35/37Cl NMR study of a chloride ion receptor and a GIPAW-DFT study of chlorine NMR interaction tensors in organic hydrochlorides

2011 ◽  
Vol 89 (7) ◽  
pp. 822-834 ◽  
Author(s):  
Rebecca P. Chapman ◽  
Jennifer R. Hiscock ◽  
Philip A. Gale ◽  
David L. Bryce
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Density Functional ◽  
Chloride Ion ◽  
Quadrupole Coupling Constant ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
High Symmetry ◽  
Coupling Constant ◽  
Quadrupole Coupling

The results of a 35/37Cl solid-state nuclear magnetic resonance (SSNMR) study of the 1-butyl-3-methylimidazolium chloride complex of meso-octamethylcalix[4]pyrrole (1) are reported. Line shapes obtained from magic-angle-spinning and stationary powder samples collected at 9.4 and 21.1 T are analyzed to provide the 35/37Cl quadrupolar tensor and chemical shift (CS) tensor and their relative orientation. The relatively high symmetry of the chloride ion coordination environment is manifested in the small value of the quadrupole coupling constant, CQ(35Cl) = 1.0 MHz. The isotropic chemical shift of 120 ppm (with respect to NaCl(s)) is at the upper edge of the typical range seen for organic hydrochlorides. Consideration of chemical shift anisotropy (span, Ω = 50 ppm) and non-coincidence of the quadrupolar and CS tensors were essential to properly simulate the experimental spectra. The utility of gauge-including projector-augmented wave density functional theory (GIPAW-DFT) calculations of chlorine quadrupolar and CS tensors in organic chlorides was explored by validation against available benchmark experimental data for solid amino acid hydrochlorides. The calculations are shown to systematically overestimate the value of the 35Cl quadrupole coupling constant. Additional calculations on various hydrated and solvated models of 1 are consistent with a structure in which solvent and water of hydration are absent.

scholarly journals Proton and Deuteron NMR Study on Single Crystals of Na2ZnCl4 · 3 H2O (Na2ZnCl4 · 3 D2O)

1973 ◽  
Vol 28 (12) ◽  
pp. 1919-1931
Author(s):  
Alarich Weiss ◽  
A. Wüst
Keyword(s):  
Principal Axis ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
Gradient Tensor ◽  
H Nmr ◽  
Nmr Study ◽  
Nuclear Quadrupole Coupling Constant ◽  
Quadrupole Coupling ◽  
Direction Cosines ◽  
Nuclear Quadrupole

Single crystal 1H- and 2H-XMR spectra of Na2ZnCl4 · 3 H2O and Xa2ZnCl4 · 3 D2O, respectively, were studied. The following results have been obtained: The positions of the hydrogens and deuterons are described in the space group C23v- P 31m with one formula unit in the unit cell. The point positions are: HI(DI) in 3m: x = 0.455 ± 4, y = 0, z = 0.556 ± 5; HII(DII) in 3m: x = 0.675 ± 4, y = 0, z = 0.466 ± 5. The angle H-O -H (D-O-D) is 107.0° and the H-H distance is 1.603 + 3 Å. Including dynamical corrections, the equilibrium positions are: HI(DI) : x = 0.459 ± 4, y - 0, z = 0.550 ± 5; HII(DII): x = 0.669 ± 4, y = 0, z = 0.464 ± 5. The H-H distance is then 1.537 ± 5 Å. From the 2H-NMR the nuclear quadrupole coupling constant of the deuterons is at T = 22 °C: e2qQ/h = 132.0 ± 1.0 kHz; η = 0.754 ± 5. The major principal axis of the electric field gradient tensor is perpendicular to the twofold axis of the molecule D2O. At T = -25 °C for the two deuteron atoms of one molecule D2O, the values (e2qQ/h)I = 239.7 ± 1.0 kHz; ηI = 0.118 ± 2; (e2qQ/h)II = 235.9 ± 1.0 kHz; ηII = 0.125 ± 2 have been found. Here the intermediate principal axis of the FGT is perpendicular to the H-O-H plane. The direction cosines of the FGTs have been determined. The activation energy for the flipping process was found to be 12.7 kcal. mol-1. The possible hydrogen bonds O-H…Cl are discussed.

Phase Transition in 4-(CH3)C6H4NH⊕3X⊖ (X = Br, I)

1984 ◽  
Vol 39 (4) ◽  
pp. 366-370
Author(s):  
V. Seshu Bai ◽  
Alarich Weiss
Keyword(s):  
Phase Transition ◽  
Quadrupole Coupling Constant ◽  
Temperature Phase ◽  
Coupling Constant ◽  
Orthorhombic Space Group ◽  
Temperature Range ◽  
Nuclear Quadrupole Coupling Constant ◽  
Resonance Frequencies ◽  
Quadrupole Coupling ◽  
Reversible Transitions

By 79,81Br and 127I NQR spectroscopy 4-(CH3)C6H4NH⊕3X⊖ , X = Br and I, and 4-(CH3)C6H4ND⊕3I⊖ were studied in the temperature range 77 ≦ TK ⪅ 340. The three compounds experience phase transitions, most likely of higher order. Two reversible transitions are observed for the para-toluidinium iodide. 7~i-n being in the temperature range 247 ⪅ T/K ⪅ 258. TII ⇌ III in the range 174 ⪅ T/K ⪅ 179. The deuterated compound shows slight shift of the transition temperatures compared to the protonated one. whereas the 127I-NQR resonance frequencies are considerably lowered as is the nuclear quadrupole coupling constant. The asymmetry parameter η, however, increases through deuteration of the NH3 group. The room temperature phase of the iodide crystallizes with an orthorhombic space group (Pmmn or Pmn21, Z = 2). Temperature dependence of the 79BrNQR spectrum of p-toluidinium bromide indicates a phase transition near T = 281 K.

ß-NMR Study of the Electric Field Gradient in the Metallic Intercalation Compound LiC6

1986 ◽  
Vol 41 (1-2) ◽  
pp. 109-112 ◽  
Author(s):  
P. Freiländer ◽  
P. Heitjans ◽  
H. Ackermann ◽  
B. Bader ◽  
G. Kiese ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Intercalation Compound ◽  
Quadrupole Coupling Constant ◽  
Layered Compound ◽  
Thermal Neutrons ◽  
Coupling Constant ◽  
Nmr Study ◽  
Nuclear Magnetic Resonance Spectra ◽  
Quadrupole Coupling ◽  
Constant E

In the layered compound LiC6polarized β-active 8Li probe nuclei were produced by captureof polarized thermal neutrons. Nuclear magnetic resonance spectra of 8Li were recorded via theβ-radiation asymmetry. The 8Li quadrupole coupling constant e2qQ/h , measured in the temperature range T = 5 . .. 500 K decreases with increasing 7 from 45.2(8) to 22.8(4) kHz.Anomalies in the overall temperature dependence are discussed in terms of phase transitionsproposed for LiC6.

scholarly journals 7Li Solid State NMR Study of a TMEDA Complex of Trimethylsilylcyclopentadienyllithium

1993 ◽  
Vol 48 (11) ◽  
pp. 1555-1557 ◽  
Author(s):  
Tanja Pietraß ◽  
Paul K. Burkert
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Solid State Nmr ◽  
Quadrupole Coupling Constant ◽  
Structural Features ◽  
Coupling Constant ◽  
X Ray ◽  
Nmr Study ◽  
Quadrupole Coupling ◽  
Increasing Temperature

7Li solid state NMR spectroscopy of Ν,Ν,N′,N′-tetramethylethylenediamine-trimethylsilylcyclopentadienyllithium yielded an unusually large quadrupole coupling constant, that decreases with increasing temperature (188-165 kHz in the temperature range 210-335 K). Structural features, known from the X-ray analysis, are compared with the NMR results.

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