Duplicate crystal structures were removed by first clustering within space groups, comparing any pair of structures with nearly identical lattice energies and densities (within 1 kJ/mol and 0.05 g/cm 3 ) using dynamic time-warping comparisons 67 of simulated X-ray diffraction patterns calculated using PLATON . Structures were then clustered further within space groups using the COMPACK algorithm, where arrays of interatomic distances within finite clusters of 30 molecules from each crystal structure were compared ; structures were identified as duplicates if all 30 molecules matched, and the 30-molecule clusters could be overlaid with an RMSD in atomic positions of below 0.3 Å. A third clustering was performed between space groups using the dynamic time-warping comparison of X-ray diffraction patterns, to obtain a final data set.