• Journal of the Korean Chemical Society
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• v.25 no.6
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• pp.351-360
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• 1981

Ultraviolet spectrophotometric investigations have been carried out on the system of durene with iodine, bromine, iodine monochloride and iodine monobromide in carbon tetrachloride. The results reveal the formation of the charge transfer complexes of the type, $C_6H_2(CH_3)_4{\cdot}X_2$ or $C_6H_2(CH_3)_4{\cdot}IX$(X denotes halogen atoms). The equilibrium constant were obtained in consideration of that absorption maxima due to the formation of the charge transfer complexes shift to blue with the increasing temperatures. The thermodynamic parameters, ${\Delta}H,\;{\Delta}G\;and\;{\Delta}S$ for the formation of the charge transfer complexes were calculated from these values. These results indicate that the relative stabilities of the durene complexes at each temperature decrease in the order, $ICl>IBr>I_2>Br_2$. This order may be a measure of their relative acidities toward durene, which is explained in terms of the relative polarizabilities of halogen molecules and the relative electronegativities of halogen atoms. These results combined with previous study of this series indicated that the relative stabilities of the polymethylbenzene complexes with iodine increase in the order; Benzene

• Journal of the Korean Chemical Society
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• v.25 no.2
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• pp.75-84
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• 1981

Ultraviolet spectrophotometric investigations have been carried out on the systems of mesitylene with iodine, bromine, iodine monochloride and iodine monobromide in carbon tetrachloride. The results reveal the formation of the charge transfer complexes of the type, $C_6H_3(CH_3)_3{\cdot}X_2$ or $C_6H_3(CH_3)_3{\cdot}IX$ (X denotes halogen atoms). The equilibrium constants were obtained in consideration of that absorption maxima due to the formation of the charge transfer complexes shift to blue with the increasing temperatures. Thermodynamic parameters, ${\Delta}H$, ${\Delta}G$ and ${\Delta}S$ for the formation of the charge transfer complexes were calculated from these values. These results indicate that the relative stabilities of the mesitylene complexes at each temperature decrease in the order, ICl > IBr > $I_2$ > $Br_2$. This order may be a measure of their relative acidities toward mesitylene, which is explaned in terms of the relative polarizabilities of halogen molecules and the relative electronegativities of halogen atoms. These results combined with previous study of this series indicated that the relative stabilities of the polymethylbenzene complexes with iodine increase in the order Benzene < Toluene < Xylene < Mesitylene Thus, analysis of these findings is discussed.

• Journal of the Korean Chemical Society
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• v.9 no.4
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• pp.161-168
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• 1965

The effect of solvents on the stabilities of the $C_6H_6{\cdot}I_2$ complex and the $C_6H_6{\cdot}ICl$ complex has been investigated through ultraviolet spectrophotometric measurements. The equilibrium constants obtained at room temperature for the formation of $C_6H_6{\cdot}I_2$ 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 $C_6H_6{\cdot}ICl$ 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 $C_6H_6{\cdot}ICl$ complex than in the $C_6H_6{\cdot}I_2$ complex. This may support the conclusion that the dative ionic structures, $C_6H_6^+{\cdots}I_2^-$ and/or ($C_6H_6I)^+{\cdots}Cl^-,$ play important roles on the reasonance stabilization of both the $C_6H_6{\cdot}I_2$ complex and the $C_6H_6{\cdot}ICl$ complex, the roles being more important in the latter complex than in the former complex.