Ligand rotations can occur freely in the clusters we are studying, but as the size of the clusters increases, approaching bulk-like systems, they would be hindered by long-range interactions. This observation provides another reason why the SOD structure of ZIF-8 is the preferred crystal formed with mIm -ligands, since the rotated ligands can point their methyl groups into the larger cavities that, in periodic structures, would be placed at the left and right of the clusters shown, thus avoiding close contacts. The influence of ligand rotation on the stabilities of the different topologies is a complex subject. A controlled rotation of ligands permits the synthesis of new topologies, but more research is needed to obtain a detailed understanding of the relation between ligand rotation and crystal structure stability, something that is out of the scope of this study.