Cocrystal Trimorphism as a Consequence of Orthogonality of Halogen- and Hydrogen-Bonding

True trimorphic cocrystals, i.e. multi-component molecular crystals of identical composition that exhibit three polymorphic structures, are exceedingly rare and so far no halogen-bonded cocrystal system was reported to exhibit trimorphism. Here, we describe a unique example of a trimorphic cocrystal exhibiting both hydrogen and halogen bonds in which the difference between polymorphs arises from their orthogonality evident by apparently independent variation of hydrogen- and halogen-bonded motifs.