For a given window, the neighbouring cage has a choice of three different positions in which to slip to adopt the lowest energy dimer configuration (Fig. )). The energy of each of these configurations is equivalent, but once one cage dimer is formed, its placement determines which positions neighbouring cages can sit at the other windows of the cage. This is because in order for there to be maximum π -π overlap, the arene rings in the vertices twist towards the neighbouring cage, which limits the orientations in which the arenes can form π -π interactions at neighbouring windows. Therefore, the choice of slip direction of one neighbouring cage influences the slip direction of the next. For a given slip direction, there are then two different arrangements the second cage can take around the central cage to maximise the number of slipped window-to-window interactions, indicated by the red arrows in Figure (c). When the slip direction of the second cage is chosen, there is only one window and slip direction accessible for a third cage to take to form 4 π -π interactions, represented as the cyan arrows in Figure (c). There is then no way to place another cage by the final window facet that would result in the same number of π -π interactions and as such the maximum number of cages in a slipped window-to-window fashion around a cage is three. As the initial choice of slip direction of the first cage is equivalent by rotation, the choice of placement by the second cage leads to two different arrangements of neighbouring cages around each cage that are mirror images of each other (Fig. ).