Polymorphic form II of 2-methyl-4-(4-methyl-1-piperazinyl)-10H-thieno[2,3-b][1,5]benzodiazepine

Acta Cryst. (2004). E60, o66–o68 [doi:10.1107/S160053680302806X]

The title compound, generic name olanzapine, is one of the newer generation atypical antipsychotic agents. Approved pharmaceutical formulations contain stable polymorphic form II of olanzapine, which is one of five known and patented forms. Crystalline unsolvated form II was obtained from solutions in anhydrous toluene and esters of acetic acid. The main building block of this crystal net is a molecular dimer. The centrosymmetric olanzapine dimer is stabilized by multiple C-H...π contacts which occur between the aliphatic (methyl or methylene groups) and aromatic (thiophene or phenyl rings) parts of the molecules. Similar dimers have been found also in the crystal structure of olanzapine solvates.

I. Wawrzycka-Gorczyca, A. E. Koziol, M. Glice and J. Cybulski