The rearrangement of cyclopropylsilylene C3H5SiH have been studied by ab initio molecular orbital theory at 3-21G and 6-31G* levels. Correlation energy corrections were computed with using second-order Moller-Plesset perturbation theory (MP2). The enthalpy △H, free energy △G, equilibrium constant K, and reaction rate constant k(T) in Eyring transition state theory of cyclopropylsilylene C3H5SiH have also been calculated. These results show that the ring expansion of cyclopropylsilylene C3H5SiH to silacyclobutene is easy to occur with a barrier of 113.4kJ/mol, while the 1,2-H shift is not competitive to the ring expansion for its much higher barrier. The rearrangement is divided into several steps and each step can be explained with Woodward-Hoffmann rule.

Key words: REACTION MECHANISM, REARRANGEMENT REACTION, KINETIC ANALYSIS, TRANSITION STATE THEORY