Molecular reorientation in sodium hydrosulfide: a deuterium nmr study

1981 ◽  
Vol 59 (11) ◽  
pp. 1585-1591 ◽  
Author(s):  
Kenneth R. Jeffrey ◽  
Roderick E. Wasylishen
Keyword(s):  
Molecular Motion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Trigonal Axis ◽  
Cubic Phase ◽  
Deuterium Nmr ◽  
Molecular Reorientation ◽  
Sodium Hydrosulfide ◽  
Nmr Study

Deuterium nmr provides a unique opportunity to verify that the molecular motion in sodium hydrosulfide, NaSH, in the trigonal phase is the flipping of the SH− ion between two positions parallel and antiparallel to the trigonal axis. Measurements of the spin–lattice relaxation time show that motion of the hydrosulfide ion is not influenced substantially by deuteration. Measurements of the deuterium nuclear quadrupole splitting, ΔνQ, over the range of temperatures where the correlation time, τc, describing the motion changes from [Formula: see text] show little change. The molecular motion of the SD− ions must, therefore, not change the deuterium quadrupolar interaction and 180° flipping of the SD− ion is the only reasonable model which fits this criterion.Spin–lattice relaxation times have also been measured in the high temperature cubic phase. At 376 K, τc was found to be 0.40 ps in agreement with neutron quasielastic scattering measurements.

A 2D deuterium NMR study of molecular reorientation in (CH3)3E+X- onium salts

2000 ◽  
Vol 78 (1) ◽  
pp. 46-50
Author(s):  
Andrew M Wachner ◽  
Kenneth R Jeffrey ◽  
Glenn H Penner
Keyword(s):  
Rotation Axis ◽  
General Structure ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Deuterium Nmr ◽  
Two Dimensional ◽  
Molecular Reorientation ◽  
Nmr Study ◽  
Onium Salts

Two dimensional deuterium NMR measurements are reported for three different onium salts (CH3)3SeNO3-d3, (CH3)3TeI-d3, and (CH3)3SI-d9. In these molecular solids with the general structure (CH3)3E+X-, three methyl groups are attached to the E atom. There is the possibility of reorientation of the methyls about their C3 axes and reorientation of the whole tri-methyl group about the C'3 axis. From an analysis of the 2D NMR exchange spectra the angle between the E-C bonds and the rotation axis for trimethyl reorientation were determined. Exchange rates and spin lattice relaxation times are given for several temperatures, to show how the mixing times for the experiments were selected. The data presented for (CH3)3TeI-d3, demonstrate that 2D techniques are sensitive to motions on a time scale an order of magnitude slower than that accessible using 1D line shape techniques.Key words: deuterium NMR, molecular motion, onium salts, two dimensional spectra.

Proton NMR Study of the Molecular Reorientation in the Trigonal Phase of Sodium Hydrosulfide

1974 ◽  
Vol 52 (23) ◽  
pp. 2370-2378 ◽  
Author(s):  
Kenneth R. Jeffrey
Keyword(s):  
Resonance Line ◽  
Relaxation Times ◽  
Spin Lattice Relaxation ◽  
Proton Nuclear Magnetic Resonance ◽  
Trigonal Axis ◽  
Molecular Reorientation ◽  
Sodium Hydrosulfide ◽  
Second Moment ◽  
Nmr Study ◽  
Trigonal Phase

The second moment of the proton nuclear magnetic resonance line and the spin–lattice relaxation time were measured as functions of temperature throughout the trigonal phase of NaSH. Motional narrowing of the resonance line occurs at about 120 K. A T1 minimum was also observed indicating molecular reorientation of the SH− ion. The second moment and the relaxation times were calculated using several models for possible SH− ion motion. The best agreement with experimental results was obtained when the proton was considered to move between two positions either side of the sulfur atom along the trigonal axis.

Molecular Dynamics in the Solid Trimethylamine-Borane Complex: A Deuterium NMR Study

1995 ◽  
Vol 50 (1) ◽  
pp. 81-89 ◽  
Author(s):  
Glenn H. Penner ◽  
Baiyi Zhao ◽  
Kenneth R. Jeffrey
Keyword(s):  
Molecular Dynamics ◽  
Variable Temperature ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Activation Energies ◽  
Spin Lattice Relaxation ◽  
Deuterium Nmr ◽  
Molecular Orbital Calculations ◽  
Spin Lattice ◽  
Nmr Study

Abstract The molecular dynamics of solid (CH3)3NBH3 is investigated by deuterium NMR spectroscopy. Variable temperature lineshape analyses yield activation energies of 27 ± 3, 19 ± 2, and 12.5 ± 2 kJ/mol for -CH3, -N(CH3)3 and -BH3 rotation, respectively. Analysis of the temperature depen­ dence of the spin-lattice relaxation times, T1 , gives activation energies of 33 ± 3, 15 ± 1.5, and 14 ± 1.5 kJ/mol, respectively. Direct comparison of rotational exchange rates (from lineshape simu­ lations) an of rotational correlation times (from T1 analyses) for -N(CH3)3 and -BH3 rotation indicate that the two motions are correlated in solid (CH3)3NBH3 and together constitute a whole molecule reorientation about the N-B bond. This is supported by an internal rotational barrier of 18.0 kJ/mol for-BH3 rotation, obtained from ab initio molecular orbital calculations at the MP2/6-31G* level.

A deuterium NMR study of guest molecular dynamics of acetone in two organic inclusion compounds

1995 ◽  
Vol 73 (12) ◽  
pp. 2196-2207 ◽  
Author(s):  
Paul S. Sidhu ◽  
Jason Bell ◽  
Glenn H. Penner ◽  
Kenneth R. Jeffrey
Keyword(s):  
Molecular Dynamics ◽  
Inclusion Compounds ◽  
Nmr Spectra ◽  
Guest Molecule ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Deuterium Nmr ◽  
Spin Lattice ◽  
Nmr Study

Deuterium nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation times (T1) are used to investigate the dynamics of the guest molecule, acetone, in tris(5-acetyl-3-thienyl)methane (TATM) and cyclotriveratrylene (CTV) inclusion compounds. 13C CPMAS powder NMR spectra were obtained for each clathrate, to verify inclusion. In acetone: TATM, the guest molecule is undergoing twofold reorientation about the CO bond, exchanging the two methyl groups. An activation energy of 20 (± 1.4) kJ/mol, for the two-site jump motion, was found, independently, from deuterium NMR spectra an T1 measurements. Acetone in CTV performs the same type of motion as acetone in TATM. Activation energies of 25.0 (± 3.2) kJ/mol and 24.1 (± 0.5) kJ/mol were determined using the same two techniques. both inclusion compounds, the rate of methyl rotation within the acetone molecule is greater than 108 Hz even at the lowest temperature measured (84 K). Analytical expressions for the spin-lattice relaxation time (T1), for a twofold jump, were derived. Calculated values of the effective quadrupolar coupling constant and T1min for the guests agree very well with the experimental data. The 84 K spectrum of acetone:TATM unexpectedly shows some asymmetry, the origin of which is discussed. Finally, these two clathrates are compared to the recently examined acetone: tri-ortho-thymotide inclusion compound. Key words: inclusion compounds, deuterium NMR, solid state NMR spectroscopy, molecular dynamics.

Molecular Motion in Solid Tetraethyl -and Tetrapropylammonium Tetrafluoroborates

1995 ◽  
Vol 50 (6) ◽  
pp. 584-588 ◽  
Author(s):  
Barbara Szafrańska ◽  
Zdzisław Pająk
Keyword(s):  
Molecular Motion ◽  
Solid Phase ◽  
Complex Cation ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Fluorine Nmr ◽  
Spin Lattice ◽  
Second Moments ◽  
Wide Range

Abstract Proton and fluorine NMR second moments and spin-lattice relaxation times for polycrystalline tetraethyl-and tetrapropylammonium tetrafluoroborates have been measured over a wide range of temperatures. Solid-solid phase transitions were found for both compounds and confirmed by DSC. Methyl group C3 reorientation followed by more complex cation motions was evidenced in the low temperature phases. Overall cation reorientation characterises the high temperature phases of both compounds. Isotropic anion reorientation was found in both salts in both phases.

1H and 19F NMR Study of Cation and Anion Motions in Guanidinium Fluoroantimonates

1995 ◽  
Vol 50 (8) ◽  
pp. 742-748 ◽  
Author(s):  
M. Grottel ◽  
A. Kozak ◽  
Z. Pająk
Keyword(s):  
Solid Phase ◽  
Relaxation Times ◽  
Activation Parameters ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Fluorine Nmr ◽  
Spin Lattice ◽  
Nmr Study ◽  
Guanidinium Cation

Abstract Proton and fluorine NMR linewidths, second moments, and spin-lattice relaxation times of polycrystalline [C(NH2)3]2SbF5 and C(NH2)3SbF6 were studied in a wide temperature range. For the pentafluoroantimonate, C3-reorientation of the guanidinium cation and C4-reorientation of the SbF5 anion were revealed and their activation parameters determined. The dynamical inequivalence of the two guanidinium cations was evidenced. For the hexafluoroantimonate, two solid-solid phase transitions were found. In the low temperature phase the guanidinium cation undergoes C3 reorien­ tation while the SbF6 anion reorients isotropically. The respective activation parameters were derived. At high temperatures new ionic plastic phases were evidenced.

Application of Adiabatic Rapid Passage Nuclear Magnetic Resonance Techniques to the Study of Molecular Motions in Solids

1974 ◽  
Vol 52 (2) ◽  
pp. 191-197 ◽  
Author(s):  
J. A. Ripmeester ◽  
B. A. Dunell
Keyword(s):  
Molecular Motion ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Adiabatic Rapid Passage ◽  
Spin Lattice ◽  
Second Moments ◽  
New Information ◽  
Rotating Frame Relaxation ◽  
Rapid Passage

The adiabatic rapid passage (ARP) technique was applied to the study of molecular motion in solids. Second moments and spin–lattice relaxation times for solid furan and benzene were derived using ARP methods from 77 °K to the respective melting points. Unusual variations of the ARP signal height and shape with temperature were observed for these solids. These effects were interpreted as being due to the presence of short rotating frame relaxation times. New information regarding molecular motion in solid furan, as well as acetic acid-d1, was obtained. Also some quantitative statements have been made regarding the conditions required to observe an ARP signal in the solid state.

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