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Coherent D-2 rotational tunneling and incoherent D-2 dynamics in a solid non-classical RuD2 complex studied by H-2 solid state NMR spectroscopy

Wehrmann, F. and Fong, T. P. and Morris, R. H. and Limbach, H. H. and Buntkowsky, G. (1999):
Coherent D-2 rotational tunneling and incoherent D-2 dynamics in a solid non-classical RuD2 complex studied by H-2 solid state NMR spectroscopy.
In: Physical Chemistry Chemical Physics, pp. 4033-4041, 1, (17), [Online-Edition: http://apps.webofknowledge.com/full_record.do?product=WOS&se...],
[Article]

Abstract

The H-2 solid state NMR spectra and T-1 relaxation data of a transition metal eta(2)-dideuterium complex, namely trans-Ru(D-2)Cl(PPh2CH2CH2PPh2)(2)PF6, have been measured in the temperature regime from 5.4 to 320 K. In the Ru-D-2 sample, coherent and incoherent exchange processes on the time scale of the quadrupolar interaction have been found, leading at low temperatures to a tunnel splitting of the H-2 NMR spectrum. With increasing temperature a slight increase of the tunnel splitting is observed, in conjunction with a strong increase of the incoherent exchange process, which finally, at temperatures above 20 K, destroys the tunnel splitting and determines the spectral line shape. For the description of the experimental spectra a Liouville formulation of the Alexander-Binsch NMR line shape theory, adapted for exchanging deuterons, is employed. It is shown that the whole evaluation of the H-2 magnetization takes place in four 2D and two 4D subspaces of the 81D Liouville space, leading to a drastic simplification of the numerical efforts in the simulation of the spectral line shapes. The height of the tunnel barrier calculated from the value of the tunnel splitting is 270 meV (6.22 kcal mol(-1)). The incoherent exchange rates extracted from the spectra and from T-1 relaxation data are analyzed in terms of a Bell tunneling model, with a temperature dependent effective potential.

Item Type: Article
Erschienen: 1999
Creators: Wehrmann, F. and Fong, T. P. and Morris, R. H. and Limbach, H. H. and Buntkowsky, G.
Title: Coherent D-2 rotational tunneling and incoherent D-2 dynamics in a solid non-classical RuD2 complex studied by H-2 solid state NMR spectroscopy
Language: English
Abstract:

The H-2 solid state NMR spectra and T-1 relaxation data of a transition metal eta(2)-dideuterium complex, namely trans-Ru(D-2)Cl(PPh2CH2CH2PPh2)(2)PF6, have been measured in the temperature regime from 5.4 to 320 K. In the Ru-D-2 sample, coherent and incoherent exchange processes on the time scale of the quadrupolar interaction have been found, leading at low temperatures to a tunnel splitting of the H-2 NMR spectrum. With increasing temperature a slight increase of the tunnel splitting is observed, in conjunction with a strong increase of the incoherent exchange process, which finally, at temperatures above 20 K, destroys the tunnel splitting and determines the spectral line shape. For the description of the experimental spectra a Liouville formulation of the Alexander-Binsch NMR line shape theory, adapted for exchanging deuterons, is employed. It is shown that the whole evaluation of the H-2 magnetization takes place in four 2D and two 4D subspaces of the 81D Liouville space, leading to a drastic simplification of the numerical efforts in the simulation of the spectral line shapes. The height of the tunnel barrier calculated from the value of the tunnel splitting is 270 meV (6.22 kcal mol(-1)). The incoherent exchange rates extracted from the spectra and from T-1 relaxation data are analyzed in terms of a Bell tunneling model, with a temperature dependent effective potential.

Journal or Publication Title: Physical Chemistry Chemical Physics
Volume: 1
Number: 17
Uncontrolled Keywords: quantum-mechanical exchange nuclear-magnetic-resonance dihydrogen complexes single-crystal molecular-hydrogen metal-hydrides methyl-groups deuteron nmr cd3 groups transition
Divisions: 07 Department of Chemistry
07 Department of Chemistry > Physical Chemistry
Date Deposited: 27 Oct 2014 20:43
Official URL: http://apps.webofknowledge.com/full_record.do?product=WOS&se...
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229LZ Times Cited:31 Cited References Count:44

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