On the question of hypoiodite ion formation in the aqueous solution of iodine: Theoretical and experimental study of H₂OI₂ complex

The possibility of hypoiodite ion formation by the hydrolysis of iodine has been examined by experimental as well as theoretical studies. The aqueous solution of iodine shows absorbance maxima near 205 nm (most intense band), 285 nm (weaker band), and 355 nm (weakest). The band at 355 nm had previously been attributed to OI^- ions. INDO CI calculations on OI^- do not give an absorbance band near any of the above wavelengths. Also, our experimental observations suggest that OI^- ions do not form in the aqueous solution. The theoretical calculations predict a H₂OI₂ complex in which two iodine atoms are arranged along the C_2v axis of H₂O and which has absorbance bands at 181 nm (most intense), 277 nm (weaker), and 365 nm (weakest). The shifts in wavelengths of maximum absorbance are explained in terms of solvation of the highly polar H₂OI₂ complex.