The crystal structures of compounds 1-3 were relaxed using the PBE+D3 functional to obtain the ground state geometry. The resultant PBE+D3 optimized lattice parameters are given in Table . Overall, PBE+D3 performs very well at replicating the experimental parameters at 150K, with all parameters remaining within 1% of experiment. To demonstrate the effect that inclusion of van de Waals corrections to the structure, we also include PBEsol for the chloride compound -while it performs similarly to PBE+D3 in two dimensions, it severely overestimates the packing in the crystallographic b direction -predominantly corresponding to the π-π stacking direction within the crystal -demonstrating the importance of dispersion interactions in correctly describing the crystal structures of these complexes.