Acta Crystallographica Section C

Crystal Structure Communications

Volume 64, Part 3 (March 2008)

organic compounds

tr3031 scheme

Acta Cryst. (2008). C64, o105-o108 [ doi:10.1107/S0108270107066279 ]

Polymorphs of gabapentin

H. A. Reece and D. C. Levendis

Abstract: Gabapentin [or 1-(aminomethyl)cyclohexaneacetic acid], C₉H₁₇NO₂, exists as a zwitterion [1-(ammoniomethyl)cyclohexaneacetate] in the solid state. The crystal structures and bonding networks of two new monoclinic polymorphs ( [beta] -gabapentin and [gamma] -gabapentin) are studied and compared with a previously reported gabapentin polymorph [ [alpha] -gabapentin: Ibers (2001). Acta Cryst. C57, 641-643]. All three polymorphs have extensive networks of hydrogen bonds between the NH₃⁺ and COO^- groups of neighbouring molecules. In [beta] -gabapentin, there is an additional weak intramolecular hydrogen bond.

Formula: C₉H₁₇NO₂