Comparison of the Four Anhydrous Polymorphs of Carbamazepine and the Crystal Structure of Form I**Supplementary material: X‐ray crystallographic information file (CIF) of triclinic CBZ (form I) is available.

For decades, carbamazepine (CBZ) has served as a model compound for groups engaged in the study of crystal polymorphism. Despite considerable effort, crystal structures for only three of its four anhydrous forms have previously been determined. Herein, we report the first single crystal X-ray structure of the high temperature modification of CBZ (form I). Form I crystallizes in a triclinic cell (P-1) having four inequivalent molecules with the...