ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 9, Number 4
JKCSEZ 9(4)
August 20, 1965 

The effect of solvents on the stabilities of the C6H6·I2 complex and the C6H6·ICl complex has been investigated through ultraviolet spectrophotometric measurements. The equilibrium constants obtained at room temperature for the formation of C6H6·I2 complex are 0.090, 0.216 and 0.328 lmole-1 in chloroform, cyclohexane and n-hexane, respectively. The corresponding equilibrium constants at room temperature for C6H6·ICl complex are 0.125, 0.676 and 0.689 lmole-1. These results indicate that the stabilities of the two complexes increase with decreasing dielectric constants of the solvents used, the increase in stability being more rapid in the C6H6·ICl complex than in the C6H6·I2 complex. This may support the conclusion that the dative ionic structures, C6H6+…I2- and/or (C6H6I)+…Cl-, play important roles on the reasonance stabilization of both the C6H6·I2 complex and the C6H6·ICl complex, the roles being more important in the latter complex than in the former complex.