scholarly journals Dynamic NMR Study of Bond Rotational Activation Parameters in Micelles

2000 ◽  
Author(s):  
Dietmar Leitner
Keyword(s):  
Activation Parameters ◽  
Dynamic Nmr ◽  
Nmr Study

Phenylfluorophosphoranes: axial–equatorial fluorine exchange in RC6H4PF3H and intermolecular exchange in the PhPF2(H)OMe–MeOH–base system

1990 ◽  
Vol 68 (3) ◽  
pp. 488-491 ◽  
Author(s):  
Leonard J. Kruczynski ◽  
Alberta E. Lemire ◽  
Kirk Marat ◽  
Alexander F. Janzen
Keyword(s):  
Shape Analysis ◽  
Ligand Exchange ◽  
Activation Parameters ◽  
Base System ◽  
Dynamic Nmr ◽  
Nmr Spectrum ◽  
First Order ◽  
H Nmr ◽  
Line Shape Analysis ◽  
Nmr Study

Activation parameters for axial–equatorial fluorine exchange in arylfluorophosphoranes RC6H4PF3H, where R = o-CF3, m-CF3, p-CF3, m-CH3, were studied by the dynamic nmr technique: [Formula: see text] varied between 53 and 56 kJ mol−1.The synthesis of difluoromethoxyphenylphosphorane, PhPF2(H)OMe, from PhPF2 and MeOH is catalyzed by small amounts of Et3N, pyridine, PhPF3H, or HF. Rapid intermolecular ligand exchange occurs in PhPF2(H)OMe after addition of methanol and a base such as triethylamine or pyridine. Under these conditions, exchange of fluorine, hydrogen, and methoxy ligands occurs, as shown by 1H, 19F, and 31P nmr. From a line shape analysis of the 31P{1H} nmr spectrum, the rate of P—F cleavage was found to be first order (1.17 ± 0.2) in Et3N concentration, with [Formula: see text] = 50 kJ mol−1 and ΔS# = −67 J mol−1 deg−1.An equilibrium constant of 1.8 at 25 °C was found for the reaction of PhPF2(H)OMe with PhPF2.Keywords: axial–equatorial fluorine exchange in RC6H4PF3H intermolecular exchange in the PhPF2(H)OMe–MeOH–base system; 31P and 19F nmr study of ligand exchange in phosphoranes.

Conformational studies by dynamic NMR. IX. Activation parameters for the barrier to C-N rotation in N,N-dimethylbenzamidine : a correction

1977 ◽  
Vol 18 (12) ◽  
pp. 1079-1080 ◽  
Author(s):  
Lodovico Lunazzi ◽  
Alessandro Dondoni ◽  
Gaetano Barbaro ◽  
Dante Macciantelli
Keyword(s):  
Activation Parameters ◽  
Dynamic Nmr ◽  
Conformational Studies

Novel tetracyclic imidazole derivatives: Synthesis, dynamic NMR study, and anti-inflammatory evaluation

2010 ◽  
pp. n/a-n/a
Author(s):  
Renata Rupčić ◽  
Marina Modrić ◽  
Antun Hutinec ◽  
Ana Čikoš ◽  
Barbara Stanić ◽  
...  
Keyword(s):  
Dynamic Nmr ◽  
Imidazole Derivatives ◽  
Nmr Study ◽  
Anti Inflammatory

Dynamic NMR Study of the Tautomerism of Bicyclic Oxalamidines: Kinetic HH/HD/DD Isotope and Solvent Effects

1994 ◽  
Vol 116 (4) ◽  
pp. 1230-1239 ◽  
Author(s):  
Gerd Scherer ◽  
Hans-Heinrich Limbach
Keyword(s):  
Solvent Effects ◽  
Dynamic Nmr ◽  
Nmr Study

Gas-Phase Dynamic NMR Study of the Internal Rotation inN-Trifluoroacetylpyrrolidine

2003 ◽  
Vol 107 (17) ◽  
pp. 3024-3029 ◽  
Author(s):  
Cristina Suarez ◽  
Elisabeth J. Nicholas ◽  
Molly R. Bowman
Keyword(s):  
Gas Phase ◽  
Internal Rotation ◽  
Dynamic Nmr ◽  
Phase Dynamic ◽  
Nmr Study

1H NMR Study of Molecular Motions in Thiourea Pyridinium Halide Inclusion Compounds

2003 ◽  
Vol 58 (11) ◽  
pp. 638-644 ◽  
Author(s):  
M. Grottel ◽  
A. Pajzderska ◽  
J. Wasicki
Keyword(s):  
Inclusion Compounds ◽  
Symmetry Axis ◽  
Activation Parameters ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Hindered Rotation ◽  
Pyridinium Cation ◽  
Spin Lattice ◽  
Nmr Study

The proton NMR second moment and spin-lattice relaxation time have been studied for polycrystalline inclusion compounds of thiourea pyridinium chloride, bromide, iodide and their perdeuterated analogues in a wide temperature range. The pyridinium cation reorientation around the pseudohexagonal C6’ symmetry axis over inequivalent barriers and hindered rotation of the thiourea molecule around its C=S bond have been revealed. The activation parameters of the both motions have been found.

ChemInform Abstract: Dynamic NMR Study of the Electronic State of Heteroaromatics. Part 8. The Influence of the Exo- and Endocyclic Heteroatoms.

ChemInform ◽  
2010 ◽  
Vol 22 (38) ◽  
pp. no-no
Author(s):  
E. KLEINPETER ◽  
R. SPITZNER ◽  
W. SCHROTH ◽  
K. PIHLAJA
Keyword(s):  
Electronic State ◽  
Dynamic Nmr ◽  
Nmr Study

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.

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