Solid-state 45Sc NMR studies of Cp*2Sc–X and Cp*2ScX(THF)

2018 ◽  
Vol 47 (37) ◽  
pp. 13063-13071 ◽  
Author(s):  
Winn Huynh ◽  
Damien B. Culver ◽  
Hosein Tafazolian ◽  
Matthew P. Conley
Keyword(s):  
Solid State ◽  
Systematic Study ◽  
Coupling Constants ◽  
Nmr Studies ◽  
Quadrupolar Coupling

A systematic study showing how the Sc–X bond affects solid-state 45Sc NMR quadrupolar coupling constants in Cp*2Sc–X.

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.

Structural analysis of lanthanum-containing battery materials using 139La solid-state NMR

2011 ◽  
Vol 89 (9) ◽  
pp. 1105-1117 ◽  
Author(s):  
Leigh Spencer ◽  
Eric Coomes ◽  
Eric Ye ◽  
Victor Terskikh ◽  
Adam Ramzy ◽  
...  
Keyword(s):  
Solid State ◽  
Structural Analysis ◽  
Lithium Ion Battery ◽  
Solid State Nmr ◽  
Nmr Spectra ◽  
Lithium Ion ◽  
Atomic Level ◽  
Coupling Constants ◽  
Battery Materials ◽  
Quadrupolar Coupling

139La solid-state NMR spectra, acquired at 21.1 and 11.7 T, have been used to evaluate the structural properties of the lithium ion battery materials, La32Li16Fe6.4O67 and Li3xLa2/3–xTiO3. In particular, atomic-level disorder in the second coordination sphere environment of lanthanum in these materials has been indicated by the observation of a distribution in the asymmetry parameters and the quadrupolar coupling constants derived from experimental NMR spectra, and supported by theoretical calculations. For comparison, 139La NMR has been obtained for the two model compounds La2O3 and LaNbO4, in which there is no atomic-level disorder. Quadrupolar coupling constants in the range of 17 to 59 MHz have been measured, and these values are supported by previous work as well as theoretical predictions performed in CASTEP. It has been shown that 139La NMR is a useful tool for the structural analysis of lithium ion battery materials, and when combined with 7Li MAS NMR and powder X-ray diffraction, can be used to determine the structure of complex solid-state electrolyte and electrode materials.

Solid State NMR Measurements for Preliminary Lifetime Assessments in λ-Irradiated and Thermally Aged Siloxane Elastomers

2004 ◽  
Vol 851 ◽  
Author(s):  
Sarah C. Chinn ◽  
Julie L. Herberg ◽  
April M. Sawvel ◽  
Robert S. Maxwell
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Magnetic Resonance ◽  
Coupling Constants ◽  
Screening Tools ◽  
Engineering Properties ◽  
Relaxation Rates ◽  
Nmr Studies ◽  
Wide Range ◽  
Nuclear Magnetic

ABSTRACTSiloxanes have a wide variety of applications throughout the aerospace industry which take advantage of their exceptional insulating and adhesive properties and general resilience. They also offer a wide range of tailorable engineering properties with changes in composition and filler content. They are, however, subject to degradation in radiatively and thermally harsh environments. We are using solid state nuclear magnetic resonance techniques to investigate changes in network and interfacial structure in siloxane elastomers and their correlations to changes in engineering performance in a series of degraded materials. Nuclear magnetic resonance (NMR) parameters such as transverse (T2) relaxation times, cross relaxation rates, and residual dipolar coupling constants provide excellent probes of changes crosslink density and motional dynamics of the polymers caused by multi-mechanism degradation. The results of NMR studies on aged siloxanes are being used in conjunction with other mechanical tests to provide insight into component failure and degradation kinetics necessary for preliminary lifetime assessments of these materials as well as into the structure-property relationships of the polymers. NMR and magnetic resonance imaging (MRI) results obtained both from high resolution NMR spectrometers as well as low resolution benchtop NMR screening tools will be presented.

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.

Spektroskopische Untersuchungen in der Festkörperchemie, XII* Re-NQR-und 1H-Breitlinien-NMR -Studien an Rhenium(YII)- Sauerstoffverbindungen / Spectroscopic Investigations in Solid State Chemistry, XII* Re NQR and 1H Wideline NMR Studies on Rhenium(VII) Oxygen Compounds

1978 ◽  
Vol 33 (8) ◽  
pp. 896-898 ◽  
Author(s):  
Paul K. Burkert ◽  
Frank M. Hutter
Keyword(s):  
Solid State ◽  
Crystal Field ◽  
Coupling Constants ◽  
Solid State Chemistry ◽  
Nmr Studies ◽  
Electrical Field ◽  
Spectroscopic Investigations ◽  
Octahedral Environment ◽  
Octahedral Crystal Field

The first Re NQR spectra of rhenium oxygen compounds with rhenium atoms in the pseudo-octahedral environment of Re2O7(H2O)2 and Re2O7(H2O)2 · 2(1,4)-dioxane were found. The values of the Re NQR coupling constants of these rhenium atoms are the highest measured until now. They show, that the gradient of the electrical field is much more sensitive to distortions of an octahedral crystal field than to distortions of a tetrahedral field.

scholarly journals Temperature Dependence of the 127I Quadrupole Coupling in Periodates with Alkyl- or Aryl-Substituted Cations of Main Group V

1986 ◽  
Vol 41 (1-2) ◽  
pp. 330-334 ◽  
Author(s):  
Dagmar G. Klobasa ◽  
Paul K. Burkert ◽  
Gerhard Müller
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Main Group ◽  
Coupling Constants ◽  
Positive Temperature ◽  
Nmr Studies ◽  
Group V ◽  
Temperature Coefficients ◽  
Quadrupole Coupling ◽  
Temperature Dependences

127I solid state NMR studies of metaperiodates with alkyl- or aryl-substituted cations of main group V revealed second order quadrupole effects with quadrupole coupling constants in the range of 2 - 7 MHz.In (C2H5)4PIO4 and (C2H5)4AsIO4 the 127I quadrupole coupling constants show normal temperature coefficients ᾱ in the order of -10-4 K-1 for 186 K < T < 300 K.For the metaperiodates with aryl-substituted cations (C6H5)4P+, (C6H5)4As+ and (C6H5)4Sb+ complicated temperature dependences of the 127I quadrupole interaction with phase transitions and anomalous positive temperature coefficients +0.2 · 10-2K-1 ≦ ᾱ ≦ +0.8 · 10-2K-1 were observed.The relevance of possible mechanisms for the anomalous temperature coefficients, like breakdown of dη - pη backbonding, negative pressure coefficients, charge transfer, orientational change of the EFG-tensor axes system and influence of reorientational motions is discussed for these compounds, including results from an X-ray investigation of (C6H5)4AsIO4 and 1H-solid state NMR measurements.

Synthesis, solid state 31P CP-MAS NMR infrared and Raman studies of mercury(II) complexes of 1,3,5-triaza-7-phosphaadamantane (PTA)

1989 ◽  
Vol 67 (8) ◽  
pp. 1319-1323 ◽  
Author(s):  
Elmer C. Alyea ◽  
Keith J. Fisher ◽  
Steve Johnson
Keyword(s):  
Solid State ◽  
Chemical Shifts ◽  
Mas Nmr ◽  
Water Soluble ◽  
Coupling Constants ◽  
Nitrate Complex ◽  
Nmr Studies ◽  
Phosphine Complexes ◽  
Water Soluble Phosphine ◽  
Cp Mas Nmr

Insoluble mercury(II) complexes of a water-soluble phosphine, 1,3,5-triaza-7-phosphaadamantane (PTA), have been studied by solid state 31P CP-MAS NMR, infrared and Raman spectroscopies. Complexes of the type (PTA)HgX2 show larger coordination chemical shifts but similar J(31P—199Hg) coupling constants to those previously observed for similar trialkylphosphine complexes. These complexes all appear to be dimeric or polymeric. The nitrate complex of the form (PTA)2Hg(NO3)2 has also been isolated and complexes of the type (PTA)4Hg2+ are shown to exist. Keywords: mercury(II) phosphine complexes, solid state 31P NMR studies.

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