The Role of Halogen Bonding in Crystal Structures of 3-Halogeno Cytisine Derivatives

The Author(s) 2012. This article is published with open access at Springerlink.com Abstract The crystal structures of three 3-halogeno derivatives of 13N-substituted cytisine have been deter- mined by X-ray diffraction. The two 13-acetyl substituted compounds, 3-bromo (1) and 3-iodo (2) are isostructural, with the isostructurality index as high as 99%. They both crystallize in monoclinic P21 space group, with unit cell parameters of a = 8.4709(10) A ˚ , b = 9.2266(12) A ˚ , c = 8.6051(10) A ˚ , b = 98.528(11)8 (1) and a = 8.2322(6) A ˚ ,