Studies on 1, 3-Dithiolium Cations. III. Stability and Electronic Structure of 4-p-Substituted Phenyl Derivatives

Abstract

Investigation of substituent effect of 4-p-substituted phenyl-1, 3-dithiolium cations was undertaken. Determination of pK_R⁺ values for a series of cations has been carried out and it was found that the electron-donating groups stabilized the cations, while the electron-withdrawing groups destabilized the cations. An excellent correlation between pK_R⁺ and Hammett's σ_p constants was established. Determination of pK_R'SH has also revealed that there was a linear correlation between pK_R'SH and Hammett's σ_p values. The electronic structures and the molecular diagrams of these cations were given by HMO calculation, and pK_R⁺ values were linearly related to the π-electron densities at C-2 positions of these cations.