Polymorphic form IV of olanzapine

Abstract

2-Methyl-4-(4-methyl-piperazin-1-yl)-10H-thieno[2,3-b][1,5]benzodiazepine, C 17H 20N 4S, commonly known as olanzapine, is a psychotropic agent that belongs to the thienobenzodi-azepine class of drugs. A new polymorph form IV was obtained upon attempted cocrystallization with nicotinamide in a 1:1 ratio from an ethyl acetate solution. Two butterfly-like mol-ecules form centrosymmetric dimers stabilized by weak C-H⋯π inter-actions between the 4-methyl-piperazin-1-yl fragment and the benzene/thio-phene aromatic system. Form IV consists of a herringbone arrangement of dimers, whereas the previously reported form II has parallel dimers. Both crystal structures are sustained by an N-H⋯N hydrogen bond. © 2011 International Union of Crystallography.