The transition state theory approach to cis-trans isomerization in substituted disilenes is presented. The activation entropy of the isomerization and corresponding Arrhenius A-factor for these substituted disilenes such as 1,2-di-tert-butyl-1,2-dimesityldisilene, 1,2-bis[bis(trimethylsilyl)amino]-1,2-dimesityldisilene and 1,2-dimethyl-1,2-diphenyldisilene have been calculated The results of the first two compounds are in good agreement with those found experimental (M. J. Michalczyk et al., 1985). No experimental result was available for the third one. The structure-entropy for such kinds of compounds is important.

Key words: DYNAMICS, CALCULATION, QUANTUM CHEMISTRY, PARAMETER, ENTROPY, ISOMERIZATION REACTION, TRANSITION STATE THEORY, REACTION RATE, CONFIGURATION, SILYLENE