Preparation and Crystal Structures of Two Polymorphic Forms of Bupropion Hydrobromide

Two polymorphic forms (forms I and IV) of antidepressant bupropion hydrobromides were prepared and characterized by powder X-ray single-crystal diffractometer. Lots of commercial substances may consist of form I. Form I crystallizes in the triclinic system, space group P (1) over bar with Z = 2, a = 7.6943(8), b = 7.9347(9), c = 13.8558(15) angstrom, a = 85.971(3), beta = 85.619(2), gamma = 65.974(3), V = 769.66(14) angstrom(3), D(c) = 1.384 g/cm(3), formula C(13)H(19)ClNOBr, F(000) = 328, mu = 2.83 mm(-1), the final R = 0.0579 and wR = 0.1282 for 1756 observed reflections with I > 2 sigma(I). Another polymorphic form,., belongs to the orthorhombic system, space group Pbca with a = 8.6365(3), b = 12.4167(4), c = 27.7299(9) angstrom, Z = 8, V = 2973.67(17) angstrom(3), D(c) = 1.432 g/cm(3), formula C(13)H(19)ClNOBr, F(000) = 1312, mu = 2.93 mm(-1), the final R = 0.044 and wR = 0.1093 for 2018 observed reflections with I > 2 sigma(I). In the crystal structure of the two polymorphic forms, expected proton transfer from HBr to amino group of bupropion molecule occurs and intramolecular and intermolecular hydrogen bonds N-H center dot center dot center dot Br are formed. These interactions result in hydrogen-bond dimers in these two forms. The bupropion molecule adopts different conformations in the two investigated solid state modifications.