The control and modulation of crystallographic structure and molecular dynamics are central to the fields of crystal engineering and molecular machines. One avenue for achieving such control is via judicious use of non-covalent bonding interactions including hydrogen bonds, halogen bonds, and chalcogen bonds, for example. We report here the results of a systematic study of the influence of halogen bonding to the nitrogen atoms of the model 2,3,5,6-tetramethylpyrazine molecule on the resulting cocrystalline architectures and rotational dynamics of its methyl groups. Using variable-temperature deuterium NMR relaxation measurements combined with single-crystal X-ray diffraction, we show how different halogen bond donors influence the crystal packing as well as the activation energy associated with methyl rotation. Building on previous work1 which identified an electronic component that contributes to a halogen-bond-induced reduction in the rotational barrier, the current work elucidates the structural and steric features which explain the observed trends in rotational activation energies across a range of halogen-bonded cocrystals. Several possible explanations for the experimental trends are also ruled out. Overall, this work sheds light on the various subtle and competing effects which can influence molecular dynamics in these systems.