Predicting the paramagnet-enhanced NMR relaxation of H2encapsulated in endofullerene nitroxides by density-functional theory calculations
Open Access
- 13 September 2013
- journal article
- Published by The Royal Society in Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
- Vol. 371 (1998) , 20110634
Abstract
We have investigated the structure and nuclear magnetic resonance (NMR) spectroscopic properties of some dihydrogen endofullerene nitroxides by means of density-functional theory (DFT) calculations. Quantum versus classical roto-translational dynamics of H2have been characterized and compared. Geometrical parameters and hyperfine couplings calculated by DFT have been input to the Solomon–Bloembergen equations to predict the enhancement of the NMR longitudinal relaxation of H2due to coupling with the unpaired electron. Estimating the rotational correlation time via computed molecular volumes leads to a fair agreement with experiment for the simplest derivative; the estimate is considerably improved by recourse to the calculation of the diffusion tensor. For the other more flexible congeners, the agreement is less good, which may be due to an insufficient sampling of the conformational space. In all cases, relaxation by Fermi contact and Curie mechanisms is predicted to be negligible.Keywords
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