Cocrystals and Salts:\nThe Structural Landscape of\nMulticomponent Solids of Chalcogenadiazoles

To explore the structural landscape of a variety of 1,3,4-chalcogenadiazoles,\nmore than 150 cocrystallization reactions with carboxylic acids as\npotential coformers were attempted, and the outcome of each was characterized\nand classified using FTIR. The results from the FTIR screen were subsequently\nconfirmed using single-crystal X-ray diffraction of products (12 were\nfound to be salts, and the remaining 5 were cocrystals). It was noted\nthat the common Δp<i>K</i><sub>a</sub> “rule”\ndid not provide reliable information on salt vs cocrystal formation\nin these systems, whereas the use of calculated interaction energies\nfor neutral vs salt-based heteromeric dimers identified a noticeable\nseparation between the two, indicating that such calculations can\noffer a useful predictor for the outcome of cocrystallization reactions.