Final Published Version
Journal of Physics and Chemistry of Solids
We report proton Zeeman relaxation rates R as a function of temperature T at 8.5 and 53 MHz in polycrystalline 1,9-dimethylphenanthrene (1,9-DMP) and l-trideuteriomethyl-9-methylphenanthrene (1, 9-DMP[1-d3]). The data are interpreted using a Davidson-Cole spectral density for intramolecular reorientation and the implications of this are discussed. R vs T−1data for 1,9-DMP[1-d3] are used to determine the parameters that characterize the reorientation of the 9-methyl group. By assuming that the parameters characterizing the dynamics of the 9-methyl group are the same in 1,9-DMP and 1,9-DMP[1-d3], we subtract out the R vs T−1 contribution of the 9-methyl group in 1,9-DMP to determine the parameters that characterize the dynamics of the 1-methyl group. We find that the barrier for reorientation of the 9-methyl group is larger than the barrier for the 1-methyl group and this is discussed in terms of the various contributions to the barrier.
Mallory, F.B., C.W. Mallory, K.G. Conn, P.A. Beckmann. 1990. "Methyl reorientation in methylphenanthrenes. II. Solid-state proton spin-lattice relaxation in the 1-CH3, 9-CH3, and 1-CD3, 9-CH3 systems." Journal of Physics and Chemistry of Solids 51. 2: 129-134.