Phosphorus-31 solid-state NMR studies of cyclic and acyclic phosphine-metal complexes. Determination of chemical shift anisotropy, scalar coupling 1JM-P (M = manganese-55, molybdenum-95/97, tungsten-183), and 55Mn quadrupolar coupling constants

1991 ◽  
Vol 30 (5) ◽  
pp. 1102-1107 ◽  
Author(s):  
Ekkehard. Lindner ◽  
Riad. Fawzi ◽  
Hermann August. Mayer ◽  
Klaus. Eichele ◽  
Klaus. Pohmer
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Metal Complexes ◽  
Solid State Nmr ◽  
Chemical Shift Anisotropy ◽  
Coupling Constants ◽  
Scalar Coupling ◽  
Nmr Studies ◽  
Quadrupolar Coupling

Determination of the 15 N chemical shift anisotropy in natural abundance samples by proton-detected 3D solid-state NMR under ultrafast MAS of 70 kHz

2019 ◽  
Vol 57 (6) ◽  
pp. 294-303 ◽  
Author(s):  
Federica Rossi ◽  
Nghia Tuan Duong ◽  
Manoj Kumar Pandey ◽  
Michele R. Chierotti ◽  
Roberto Gobetto ◽  
...  
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Solid State Nmr ◽  
Chemical Shift Anisotropy ◽  
Natural Abundance ◽  
3D Solid

A solid state NMR and molecular orbital study of hydroxylammonium chloride

1999 ◽  
Vol 77 (11) ◽  
pp. 1813-1820 ◽  
Author(s):  
Glenn H Penner ◽  
YC Phillis Chang ◽  
H Michelle Grandin
Keyword(s):  
Activation Energy ◽  
Solid State ◽  
Chemical Shift ◽  
Molecular Orbital ◽  
Solid State Nmr ◽  
Coupling Constants ◽  
Basis Sets ◽  
Exponential Factor ◽  
Line Shapes ◽  
Quadrupolar Coupling

Deuterium and nitrogen-15 NMR spectroscopy has been used to measure the 2H quadrupolar coupling and 15N chemical shift tensors in solid hydroxylammonium chloride, NH3OH+Cl-, (HAC). In addition, the NH3 and OH dynamics have been investigated by variable temperature 2H line shapes and T1 measurements. The Arrhenius activation energy for NH3 rotation is 22.5 ± 1.8 kJ/mol with a pre-exponential factor of 8 ± 3 × 1012 s-1 from line shapes and 21.3 ± 2 kJ/mol with an infinite temperature correlation time, τinf,, of 5.0 ± 0.4 × 10-14 s from the T1 analysis. The latter value corresponds to a pre-exponential factor of 6.7 ± 0.5 × 1012 s-1, if a three-site exchange is assumed. There was no evidence for OH reorientation up to 405 K, indicating a rather strong OH···Cl hydrogen bond. Previously reported inconsistencies between crystal structure and molecular orbital derived N-O bond lengths are cleared up by performing geometry optimizations with large basis sets and taking electron correlation into account. The internal rotational potential for the isolated HA cation is calculated to be 5.8 kJ/mol at the MP2/6-31G** level, with the trans geometry preferred. Calculations that employ the neutron diffraction geometry and include the Cl- anions that surround the HA+ cation yield an upper limit for the activation energy for NH3 group rotation of 62 kJ/mol. Analysis of the deuterium spectrum and T1 data yield nuclear quadrupolar coupling constants of 160 ± 5 kHz and 194 ± 5 kHz (η = 0.50 ± 0.05) for the ND3 and OD deuterons, respectively. Density functional calculations of the deuterium and nitrogen-14 nuclear quadrupolar coupling constants at the B3LYP level show that it is necessary to include the influence of the surrounding chloride anions. We have also shown that it is possible to obtain accurate proton chemical shifts from the deuterium MAS spectrum of solid HAC-d4.Key words: solid state NMR, molecular dynamics, nitrogen 15 chemical shift anisotropy.

Cobalt-59 chemical shift and quadrupolar tensors of simple octahedral cobalt(III) complexes

2001 ◽  
Vol 79 (3) ◽  
pp. 296-303
Author(s):  
Christopher W Kirby ◽  
William P Power
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Principal Components ◽  
Solid State Nmr ◽  
Nmr Spectra ◽  
Line Shapes ◽  
Quadrupolar Coupling ◽  
Molecular Frame ◽  
Specific Ligand

Analysis of the solid-state powder 59Co NMR spectra of ten simple inorganic cobalt(III) complexes at 11.75, and in most cases, 4.7 T have permitted the assignment of specific ligand planes to ranges of values of the observed chemical shift principal components. The relevant chemical shift components were determined from the simulations of the powder line shapes. These simulations also provided the relative orientations of the chemical shift (CS) and electric field gradient (efg) tensors, as well as magnitude and asymmetry of the 59Co quadrupolar coupling. Using symmetry arguments and ab initio calculations, as appropriate or necessary, the orientations of the efg tensors in the molecular frame were deduced. This allowed the determination of the CS tensors in the molecular frame and thus assignment of the ligand planes responsible for the observed values of chemical shifts.Key words: cobalt, chemical shift, quadrupolar coupling, solid state NMR.

scholarly journals Oxygen-17 NMR spectroscopy of water molecules in solid hydrates

2016 ◽  
Vol 94 (3) ◽  
pp. 189-197 ◽  
Author(s):  
Sherif Nour ◽  
Cory M. Widdifield ◽  
Libor Kobera ◽  
Kevin M. N. Burgess ◽  
Dylan Errulat ◽  
...  
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Density Functional ◽  
Chemical Shifts ◽  
Sodium Perchlorate ◽  
Coupling Constants ◽  
Water Molecules ◽  
Potassium Oxalate ◽  
Nmr Studies ◽  
Quadrupolar Coupling

17O solid-state NMR studies of waters of hydration in crystalline solids are presented. The 17O quadrupolar coupling and chemical shift (CS) tensors, and their relative orientations, are measured experimentally at room temperature for α-oxalic acid dihydrate, barium chlorate monohydrate, lithium sulfate monohydrate, potassium oxalate monohydrate, and sodium perchlorate monohydrate. The 17O quadrupolar coupling constants (CQ) range from 6.6 to 7.35 MHz and the isotropic chemical shifts range from –17 to 19.7 ppm. The oxygen CS tensor spans vary from 25 to 78 ppm. These represent the first complete CS and electric field gradient tensor measurements for water coordinated to metals in the solid state. Gauge-including projector-augmented wave density functional theory calculations overestimate the values of CQ, likely due to librational dynamics of the water molecules. Computed CS tensors only qualitatively match the experimental data. The lack of strong correlations between the experimental and computed data, and between these data and any single structural feature, is attributed to motion of the water molecules and to the relatively small overall range in the NMR parameters relative to their measurement precision. Nevertheless, the isotropic chemical shift, quadrupolar coupling constant, and CS tensor span clearly differentiate between the samples studied and establish a ‘fingerprint’ 17O spectral region for water coordinated to metals in solids.

A solid-state 133Cs nuclear magnetic resonance and X-ray crystallographic study of cesium complexes with macrocyclic ligands

2000 ◽  
Vol 78 (7) ◽  
pp. 975-985
Author(s):  
Alan Wong ◽  
Simon Sham ◽  
Suning Wang ◽  
Gang Wu
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Chemical Shift ◽  
Solid State Nmr ◽  
Chemical Shifts ◽  
Macrocyclic Ligand ◽  
Chemical Shift Anisotropy ◽  
Macrocyclic Ligands ◽  
X Ray

We report solid-state NMR determination of the 133Cs chemical shift anisotropy (CSA) for a series of cesium complexes with macrocyclic ligands. It was found that the isotropic 133Cs chemical shifts are related to the number of oxygen atoms to which the Cs+ ion is coordinated. The 133Cs chemical shifts were found to correlate with average Cs-O distances. We also attempt to use the established correlation to deduce Cs+ coordination environment for compounds with unknown structures. We also report the X-ray determination of the crystal structure for Cs(DB18C6)2SCN•1/2CH3OH•1/2H2O. The compound crystallizes in monoclinic, a = 14.503(2), b = 15.152(3), c = 39.989(6) Å, β = 90.796(8)°, space group P21/c, Z = 8. There are two independent molecules in the asymmetric unit cell where each of the two Cs+ ions is coordinated to two DB18C6 ligand molecules forming a sandwich-type structure.Key words: solid state NMR, alkali metal, 133Cs chemical shift, macrocyclic ligand, crystal structure.

Solid State NMR Studies of the Adsorbed States of Formic Acid on Y Zeolites

1980 ◽  
Vol 3 ◽  
Author(s):  
T. Michael Duncan ◽  
Robert W. Vaughan
Keyword(s):  
Solid State ◽  
Formic Acid ◽  
Solid State Nmr ◽  
Double Resonance ◽  
Chemical Shift Anisotropy ◽  
Surface States ◽  
Cross Polarization ◽  
Nmr Studies ◽  
Y Zeolites ◽  
Nmr Techniques

ABSTRACTSeveral multiple-pulse double-resonance NMR techniques have been applied to isolate and characterize the spectra of the adsorbed states of formic acid on two Y zeolites. The two surface states, bidentatT3 and ynidentate, possess different motional properties and 13C - H cross-polarization techniques may be used to separate the spectra. The 13C chemical shift anisotropy is founa to iorrelate with the symmetry of the formate species. The H spectrum of the carbonyl hydrogen, selectively observed with the dipolardifference method, indicates that this hydrogen becomes more acidic upon adsorption.

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