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.

Bernstein, 1999, Concomitant polymorphs, Angew Chem Int Ed Engl, 38, 3441, 10.1002/(SICI)1521-3773(19991203)38:23<3440::AID-ANIE3440>3.0.CO;2-# Kariuki, 2000, Polymorphism in p‐hydroxybenzoic acid: The effect of intermolecular hydrogen bonding in controlling proton order versus disorder in the carboxylic acid dimer motif, Angew Chem Int Ed Engl, 39, 4485, 10.1002/1521-3773(20001215)39:24<4485::AID-ANIE4485>3.0.CO;2-T Gavezzotti, 1995, Polymorphic forms of organic crystals at room conditions: Thermodynamic and structural implications, J Am Chem Soc, 117, 12299, 10.1021/ja00154a032 Dunitz, 1995, Disappearing polymorphs, Acc Chem Res, 28, 193, 10.1021/ar00052a005 Steiner, 1997, Unrolling the hydrogen bond properties of C–H···O interactions, Chem Commun, 727, 10.1039/a603049a Brittain, 1999 Brock, 1996, Investigations of the systematics of crystal packing using the Cambridge Structural Database, J Res Natl Inst Stand Technol, 101, 321, 10.6028/jres.101.033 Henck, 1997, Polymorphism of drug substances: An economic challenge, Pharm Ind, 59, 165 McCrone, 1957 Desiraju, 1991, The C–H···O hydrogen‐bond in crystals: What is it?, Acc Chem Res, 24, 290, 10.1021/ar00010a002 Desiraju, 1997, Designer crystals: Intermolecular interactions, network structures, and supramolecular synthons, Chem Commun, 1475, 10.1039/a607149j Yu, 2000, Crystallization and polymorphism of conformationally flexible molecules: Problems, patterns, and strategies, Org Process Res Dev, 4, 396, 10.1021/op000028v Kuhnert‐Brandstätter, 1968, Beitrag zur mikroskopischen Charakterisierung und Identifizierung von Arzneimitteln unter Einbeziehung der UV‐Spektrophotometrie, Sci Pharm, 36, 164 Pohlmann, 1975, Polymorphism, particle‐size and blood level values of carbamazepine, Pharmazie, 30, 709 Reboul, 1981, 5H‐5‐Dibenz[b,f]azepinecarboxamide‐5 (carbamazepine), Acta Crystallogr Sect B, 37, 1844, 10.1107/S0567740881007383 Himes, 1981, Structure of carbamazepine: 5H‐Dibenz[b,f]azepine‐5‐carboxamide, Acta Crystallogr Sect B, 37, 2242, 10.1107/S0567740881008522 Kaneniwa, 1984, Hygroscopicity of carbamazepine crystalline powders, Yakugaku Zasshi, 104, 184, 10.1248/yakushi1947.104.2_184 Umeda, 1984, Kinetics of the thermal transition of carbamazepine polymorphic forms in the solid state, Yakugaku Zasshi, 104, 786, 10.1248/yakushi1947.104.7_786 Kala, 1986, Zur Polymorphie des Carbamazepins, Acta Pharm Technol, 32, 72 Lefebvre, 1986, Polymorphic transitions of carbamazepine during grinding and compression, Drug Dev Ind Pharm, 12, 1913, 10.3109/03639048609042617 Krahn, 1987, Relations between several polymorphic forms and the dihydrate of carbamazepine, Pharm Acta Helv, 62, 247 Lowes, 1987, Physicochemical properties and X‐Ray structural studies of the trigonal polymorph of carbamazepine, J Pharm Sci, 76, 744, 10.1002/jps.2600760914 Lisgarten, 1989, Crystal and molecular structure of 5‐carbamyl‐5H‐dibenzo[b,f]azepine, J Crystallogr Spectrosc Res, 19, 641, 10.1007/BF01179836 Behme, 1991, Heat of fusion measurement of a low melting polymorph of carbamazepine that undergoes multiple‐phase changes during differential scanning calorimetry analysis, J Pharm Sci, 80, 986, 10.1002/jps.2600801016 Dugué, 1991, Polymorphism of carbamazepine: Solid‐state studies on carbamazepine dihydrate, Pharm Acta Helv, 66, 307 Borka, 1992, Semiquantitative IR spectroscopy of the crystal polymorphs of carbamazepine: A special case in the Ph. Eur. and USP, Pharm Acta Helv, 67, 231 McMahon, 1996, Characterization of dihydrates prepared from carbamazepine polymorphs, J Pharm Sci, 85, 1064, 10.1021/js960117e Céolin, 1997, X‐ray characterization of the triclinic polymorph of carbamazepine, J Pharm Sci, 86, 1062, 10.1021/js960338k Roberts, 2000, Mechanical property predictions for polymorphs of sulphathiazole and carbamazepine, Eur J Pharm Sci, 9, 277, 10.1016/S0928-0987(99)00065-2 Kobayashi, 2000, Physicochemical properties and bioavailability of carbamazepine polymorphs and dihydrate, Int J Pharm, 193, 137, 10.1016/S0378-5173(99)00315-4 Rustichelli, 2000, Solid‐state study of polymorphic drugs: Carbamazepine, J Pharm Biomed Anal, 23, 41, 10.1016/S0731-7085(00)00262-4 Lang, 2002, Form IV of carbamazepine, J Pharm Sci, 91, 1186, 10.1002/jps.10093 Nakata, 1987, Crystal structure of 2‐pyrazinecarboxamide, C5H5N3O, Memoirs of Osaka Kyoiku University, Series III, 36, 93 Bar, 1985, Conformational polymorphism. IV. The crystal and molecular structures of form II, form III, and form V of 4‐amino‐N‐2‐pyridinylbenzenesulfonamide (sulfapyridine), J Pharm Sci, 74, 255, 10.1002/jps.2600740307 Yu, 2000, Thermochemistry and conformational polymorphism of a hexamorphic crystal system, J Am Chem Soc, 122, 585, 10.1021/ja9930622 Hughes, 1999, A new polymorph of sulfathiazole, Acta Crystallogr Sect C, 55, 1831, 10.1107/S0108270199010112 Lang, 2002, The use of polymer heteronuclei for crystalline polymorph selection, J Am Chem Soc, 124, 14834, 10.1021/ja0286526 Bernstein, 1995, Patterns in hydrogen bonding: Functionality and graph set analysis in crystals, Angew Chem Int Ed Engl, 34, 1555, 10.1002/anie.199515551 Etter, 1990, Encoding and decoding hydrogen‐bond patterns of organic compounds, Acc Chem Res, 23, 120, 10.1021/ar00172a005 Burger, 1979, On the polymorphism of pharmaceuticals and other organic molecular crystals. I. Theory of thermodynamic rules, Mikrochim Acta, II, 259, 10.1007/BF01197379 Lommerse, 2000, A test of crystal structure prediction of small organic molecules, Acta Crystallogr Sect B, 56, 697, 10.1107/S0108768100004584