3. RESULTS AND DISCUSSION The experimental data presented in Figures and appears sufficiently distinctive to be interpreted; there are significant changes in both 2 H lineshapes (Figure ) and in T1 (Figure ) with temperature. Indeed, the spectrum of the acetone solvate, Figure , can be modelled in simple terms; the spectra are relatively narrow at all temperatures, consistent with fast dynamics of the CD3 groups, and the changes of the spectrum with temperature can be reproduced by a simple two-state Markov model corresponding to "intermediate timescale" C2 jumps about the C=O axis (see Figure of the Supplementary Information). As shown by the molecular dynamics results, however, this naïve model is incorrect and the jump rates obtained from this widely used analysis are essentially meaningless.