Molecular and crystal structure, and stability of 4-bromobenzyltriphenylphosphonium diiodobromide

Abstract

Complexation in system 4-bromobenzyltriphenylphosphonium bromide–molecular iodine in chloroform has been studied. The limit number of iodine molecules coordinated by 4-bromobenzyltriphenylphosphonium bromide in solution and the stability constant of the complex have been determined by a spectrophotometric method using iodine average number functions. According to the X-ray diffraction data, the crystal structure of the charge transfer complex is formed by anion BrI₂⁻ and cation [(C₆H₅)₃PCH₂C₆H₄Br]⁺. In a crystal, translationally identical cations C₂₅H₂₁BrP⁺ form stacks along the y axis. Diiodobromide anions dimerized due to the I–I shortened contacts are located between the stacks.