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Hydrogen deuterium isotope effect on exchange rates in eta(2) bond transition metal dihydrogen complexes revealed by H-2 solid state NMR spectroscopy

Wehrmann, F. and Albrecht, J. and Gedat, E. and Kubas, G. J. and Eckert, J. and Limbach, H. H. and Buntkowsky, G. (2002):
Hydrogen deuterium isotope effect on exchange rates in eta(2) bond transition metal dihydrogen complexes revealed by H-2 solid state NMR spectroscopy.
In: Journal of Physical Chemistry A, pp. 2855-2861, 106, (12), [Online-Edition: http://apps.webofknowledge.com/full_record.do?product=WOS&se...],
[Article]

Abstract

A selectively eta(2)-D-2 labeled isotopomer of the complex W(PCy3)(2) (CO)(3)) (eta(2)-D-2) has been synthesized and the H-2 NMR spectra and spin lattice relaxation rates of this complex have been measured in the temperature regime of 50 K to 300 K. The spectra have been analyzed employing a model of a combination of homonuclear dipolar D-D interaction and deuterium quadrupolar interaction and a D-D distance of 0.89 +/- 0.1 Angstrom. The line width of the spectra exhibits a weak temperature dependence at temperatures above 150 K. This temperature dependence is interpreted as a slight decrease of the quadrupolar coupling with increasing temperature, which is an indication of a change of the M-D-2 distance with changing temperatures. The spin lattice relaxation data of the complex exhibit pronounced deviations from a simple Arrhenius behavior at lower temperatures, indicating the presence of a quantum mechanical tunneling process. This process is analyzed in terms of a simple one-dimensional Bell tunnel model. A comparison with INS data from the H-2 complex reveals a strong isotope effect of 2 x 10(3) for the exchange rates of the deuterons.

Item Type: Article
Erschienen: 2002
Creators: Wehrmann, F. and Albrecht, J. and Gedat, E. and Kubas, G. J. and Eckert, J. and Limbach, H. H. and Buntkowsky, G.
Title: Hydrogen deuterium isotope effect on exchange rates in eta(2) bond transition metal dihydrogen complexes revealed by H-2 solid state NMR spectroscopy
Language: English
Abstract:

A selectively eta(2)-D-2 labeled isotopomer of the complex W(PCy3)(2) (CO)(3)) (eta(2)-D-2) has been synthesized and the H-2 NMR spectra and spin lattice relaxation rates of this complex have been measured in the temperature regime of 50 K to 300 K. The spectra have been analyzed employing a model of a combination of homonuclear dipolar D-D interaction and deuterium quadrupolar interaction and a D-D distance of 0.89 +/- 0.1 Angstrom. The line width of the spectra exhibits a weak temperature dependence at temperatures above 150 K. This temperature dependence is interpreted as a slight decrease of the quadrupolar coupling with increasing temperature, which is an indication of a change of the M-D-2 distance with changing temperatures. The spin lattice relaxation data of the complex exhibit pronounced deviations from a simple Arrhenius behavior at lower temperatures, indicating the presence of a quantum mechanical tunneling process. This process is analyzed in terms of a simple one-dimensional Bell tunnel model. A comparison with INS data from the H-2 complex reveals a strong isotope effect of 2 x 10(3) for the exchange rates of the deuterons.

Journal or Publication Title: Journal of Physical Chemistry A
Volume: 106
Number: 12
Uncontrolled Keywords: quantum-mechanical exchange h-h bond molecular-hydrogen single-crystal nuclear-dynamics methyl-groups cd3 groups ligand coherent hydride
Divisions: 07 Department of Chemistry
07 Department of Chemistry > Physical Chemistry
Date Deposited: 27 Oct 2014 20:52
Official URL: http://apps.webofknowledge.com/full_record.do?product=WOS&se...
Additional Information:

534LU Times Cited:18 Cited References Count:70

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