scholarly journals NMR study of Li distribution in Li7−xHxLa3Zr2O12 garnets

2015 ◽  
Vol 3 (10) ◽  
pp. 5683-5691 ◽  
Author(s):  
G. Larraz ◽  
A. Orera ◽  
J. Sanz ◽  
I. Sobrados ◽  
V. Diez-Gómez ◽  
...  
Keyword(s):  
Variable Temperature ◽  
Temperature Measurements ◽  
Dynamic Processes ◽  
Relative Population ◽  
Nmr Study

We present a NMR investigation of 6Li7−xHxLa3Zr2O12 (0 ≤ x ≤ 5) garnets to study the distribution of Li ions. The facile H+/Li+ exchange alters the relative population of Li sites, and allows the identification of 3 different bands ascribed to Li in different environments. Variable temperature measurements indicated the presence of dynamic processes between octahedral and tetrahedral Li sites.

Dynamic Behaviour of Tetramethylethylene Diamine (TMEDA) Ligands in Solid Organolithium Compounds: A Variable Temperature 13C and I5N CP/MAS NMR Study

1995 ◽  
Vol 50 (4-5) ◽  
pp. 429-438 ◽  
Author(s):  
Wolfgang Baumann ◽  
Yuri Oprunenko ◽  
Harald Günther
Keyword(s):  
Nmr Spectroscopy ◽  
Energy Barrier ◽  
Dynamic Behaviour ◽  
Variable Temperature ◽  
Mas Nmr ◽  
Organometallic Complexes ◽  
Dynamic Processes ◽  
Ring Inversion ◽  
Nmr Study ◽  
Cp Mas Nmr

Abstract The dynamic behaviour of tetramethylethylene diamine (TMEDA) ligands in three organometallic complexes, dimeric phenyllithium, [Li(tmeda)μ-Ph]2 (1), lithium cyclopentadienide, [Li(tmeda)]C5H5 (2), and dilithium naphthalendiide, trans-[Li(tmeda)]2C10H8 (3), has been studied by CP/MAS 13C and 15N as well as 7Li MAS NMR spectroscopy of powdered samples. Two dynamic processes with free activation enthalpies of 40 and 68 kJ mol-1, respectively, were detected for 1. The first one can be assigned to ring inversion of the five-membered Li-TMEDA rings, while the second is caused by a complete rotation of the TMEDA ligands or a ring inversion of the central four-membered C-Li-C-Li metallacycle. Fast rotation of the ligands on the NMR time scale was found for 2, while 3 shows 180° ring flips of the Li-TMEDA groups, which are characterized by an energy barrier ΔG" (317) of 64 kJ mol-1

scholarly journals Variable-Temperature Multinuclear Solid-State NMR Study of Oxide Ion Dynamics in Fluorite-Type Bismuth Vanadate and Phosphate Solid Electrolytes

2019 ◽  
Vol 31 (5) ◽  
pp. 1704-1714 ◽  
Author(s):  
Matthew T. Dunstan ◽  
David M. Halat ◽  
Matthew L. Tate ◽  
Ivana Radosavljevic Evans ◽  
Clare P. Grey
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Solid Electrolytes ◽  
Variable Temperature ◽  
Bismuth Vanadate ◽  
Ion Dynamics ◽  
Nmr Study ◽  
Fluorite Type ◽  
Oxide Ion

ChemInform Abstract: A VARIABLE TEMPERATURE NMR STUDY OF CARBONYLDIPHENYLACETYLENE TRIS(PI-CYCLOPENTADIENYLRHODIUM) AND ITS BIS(PENTAFLUOROPHENYL)DERIVATIVE

1973 ◽  
Vol 4 (48) ◽  
pp. no-no
Author(s):  
T. YAMAMOTO ◽  
A. R. GARBER ◽  
G. M. BODNER ◽  
L. J. TODD ◽  
M. D. RAUSCH ◽  
...  
Keyword(s):  
Variable Temperature ◽  
Nmr Study

scholarly journals Cation effects on dynamics of ligand-benzylated formazanate boron and aluminium complexes

2020 ◽  
Vol 49 (26) ◽  
pp. 9094-9098
Author(s):  
Ranajit Mondol ◽  
Edwin Otten
Keyword(s):  
Variable Temperature ◽  
Dynamic Processes ◽  
Cation Effects

The dynamic processes present in ligand-benzylated formazanate boron and aluminium complexes are investigated using variable temperature NMR experiments and lineshape analyses.

Exploring Dynamics and Stereochemistry in Mechanically-Interlocked Compounds

2005 ◽  
Vol 70 (10) ◽  
pp. 1493-1576 ◽  
Author(s):  
Scott A. Vignon ◽  
J. Fraser Stoddart
Keyword(s):  
Self Assembly ◽  
Structural Changes ◽  
Variable Temperature ◽  
Molecular Switches ◽  
Dynamic Processes ◽  
Condensed Phases ◽  
H Nmr ◽  
Structural Types ◽  
Solution Dynamics ◽  
Stereochemical Properties

The advent of self-assembly and template-directed synthetic protocols has led to a tremendous surge in the number of mechanically-interlocked compounds being prepared and studied. As these investigations are being carried out, it is becoming increasingly apparent that many of these compounds, known as catenanes and rotaxanes, possess unique dynamic and stereochemical properties. In addition, the drive to create molecular switches and machines for nanotechnological applications has generated a need to understand how to control those properties in condensed phases. Here, we present an overview of the field with regard to the solution dynamics and stereochemistry of mechanically-interlocked compounds - as well as to some related structural types - and review the recent results from our own research in some detail. 1H NMR spectroscopy has proven to be a powerful tool for probing both degenerate and nondegenerate dynamic processes in these compounds, as well as for identifying stereoisomers if they are present in solution. The results of several variable temperature NMR investigations on the effects of structural changes upon the dynamic processes and stimulated relative motions of components in catenanes and rotaxanes, as well as in some self-complexes and pretzelanes, are discussed. A review with 90 references.

Nuclear magnetic resonance studies of the methylammonium hexahalotellurates

1992 ◽  
Vol 70 (3) ◽  
pp. 849-855 ◽  
Author(s):  
Mark R. MacIntosh ◽  
Marco L. H. Gruwel ◽  
Katherine N. Robertson ◽  
Roderick E. Wasylishen
Keyword(s):  
Line Shape ◽  
Nmr Spectra ◽  
Room Temperature ◽  
Solid Phase ◽  
Variable Temperature ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
H Nmr ◽  
Nmr Study ◽  
Correlated Motion

A 2H and 14N NMR study of the solid methylammonium hexahalotellurates, (MA)2TeX6 (MA = CH3ND3+ or CD3NH3+, X = Cl, Br, and I), has been undertaken to characterize the dynamics of the methylammonium (MA) ion as a function of temperature. At room temperature, the MA ion in the hexachlorotellurate (solid II) is confined to C3 jumps about the C—N axis while a small angle libration of the C—N axis is occurring. In the room temperature phase, solid I, of (MA)2TeBr6 and (MA)2TeI6 the MA ions are performing overall reorientations on the ps time scale, averaging the 2H nuclear quadrupolar interactions to zero. Variable temperature 2H NMR spin-lattice relaxation times, T1, indicate an activation energy, EA, for "isotropic" reorientations of the CH3ND3+ ion of 5.2 ± 0.5 and 2.6 ± 0.3 kJ mol−1 for X = Br and I, respectively. Deuterium T1 values for C-deuterated MA ion in the hexaiodotellurate indicate an EA for whole-ion reorientation of 3.1 ± 0.3 kJ mol−1. At any given temperature, the correlation time, τc, derived from the T1 results was found to be the same for the two deuterium-labelled hexaiodotellurates. The similarity of both the EA and the τc values implies correlated motion of the methyl and ammonium groups. The 14N T1 results for solid I of (MA)2TeI6 indicate that C—N axis motions, with an EA = 5.6 ± 0.6 kJ mol−1, are more hindered than N—D or C—D bond dynamics. The 2H NMR spectra for (MA)2TeI6 (solid II) and (MA)2TeBr6 (solids II, III, and IV) are characterized by a Pake doublet line shape. The measured peak-to-peak splittings are less than what is predicted by C3 motion about the molecular symmetry axis. It is possible to model these line shapes by postulating that C3 rotations of the methyl and ammonium groups occur as the C—N axis librates in an effective cone about the position of the static molecular axis. For (CH3ND3)2TeBr6 and (CD3NH3)3TeBr6 the peak-to-peak splittings in the 2H NMR spectra were measured as a function of temperature in solid phases II, III, and IV and were found to be similar. Finally, the 2H NMR line shape relaxation for (MA)2TeBr6 (solid III) displays an orientation dependence indicating that rotations about the C—N axis are discrete rather than diffusive in nature. For solid phase II of (MA)2TeCl6, the line shape is observed to relax isotropically, implying that continuous C3 rotations are taking place. Keywords: 2H and 14N NMR, methylammonium hexahalotellurates, molecular motion.

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