Molecular complexes bromine-dioxane

The structure of ra-complexes has been examined by the X-ray crystallographic studies of solid samples and by the spectral measurement of heterocycle-halogen equilibria in solution. By the former approach the structure of the solid 1 2 pyridine-molecular iodine complex has been shown to consist principally of two pyridine molecules collinearly bonded to an iodine atom and of linear triiodide units. Moreover, in the 1 1 complex of dioxane and bromine, the heterocyclic oxygen-bromine-bromine linkages are also collinear.4 In the latter type of study, interest in the well-known phenomenon of brown iodine solutions has occasioned the measurement of the stability constants for many complexes of halogen and heterocycles.25, 29 Information concerning their structure in solution comes from a consideration of the relative size of such constants as a function of heterocycle structure. Thus, the fact that bromine complexes of both 8-bromo- and 8-methylquinolines possess stability constants (K = 1.1 and 4.8 liters/mole) much smaller than that of quinoline itself... 

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