Iodine, iodine monochloride and bromine interaction with 1,3,5-triazine in chloroform solution

Abstract

The interaction between 1,3,5-triazine as n-donor, with I2, ICl and Br2 as σ-acceptor have been studied spectrophotometrically in chloroform at 25 °C. The results obtained for iodine indicate that of the complex [triazineIδ+-Iδ-] is formed through an equilibrium step which is followed by slow conversion to [triazineI +I-] and a fast reaction with iodine to produce [triazineI+I3-], through nonequilibrium steps. The equilibrium and rate constants of the recent reactions were measured. In the case of ICl the formation of [(triazine)2I+ICl 2-] by an equilibrium step is confirmed. The stability constant of the resulting complex was evaluated from the computer fitting of the absorbance vs. mole ratio data. The interaction with bromine involves only partial charge transfer which results in a blue-shift and an increase in the molar absorptivity (ε) of Br2. Based on the comparison of the results, it has been concluded that the interactions vary in the order ICl ≫ I2 > Br2.