Document Type
Article
Version
Author's Final Manuscript
Publication Title
Solid State Nuclear Magnetic Resonance
Volume
38
Publication Date
2010
Abstract
We have measured the solid state nuclear magnetic resonance (NMR) 1H spin-lattice relaxation rate from 93 to 340 K at NMR frequencies of 8.5 and 53 MHz in 5-t-butyl-4-hydroxy-2-methylphenyl sulfide. We have also determined the molecular and crystal structures from X-ray diffraction experiments. The relaxation is caused by methyl and t-butyl group rotation modulating the spin–spin interactions and we relate the NMR dynamical parameters to the structure. A successful fit of the data requires that the 2-methyl groups are rotating fast (on the NMR time scale) even at the lowest temperatures employed. The rotational barrier for the two out-of-plane methyl groups in the t-butyl groups is 14.3±2.7 kJ mol−1 and the rotational barrier for the t-butyl groups and their in-plane methyl groups is 24.0±4.6 kJ mol−1. The uncertainties account for the uncertainties associated with the relationship between the observed NMR activation energy and a model-independent barrier, as well as the experimental uncertainties.
Citation
Lauren C. Pope, Arnold L. Rheingold, and Peter A. Backmann. 2010. "A proton spin-lattice relaxation rate study of methyl and t-butyl group reorientation in the solid state." Solid State Nuclear Magnetic Resonance 38.1: 31-35.
DOI
http://www.sciencedirect.com/science/article/pii/S0926204010000329 - sec4