The insertion reactions of the silylenoid H2C＝SiLiBr to RH (R＝F, OH, NH2) were studied by using the DFT B3LYP and QCISD methods. The geometries of the stationary points on the potential energy surfaces of the reactions were optimized at the B3LYP/6-311＋G (d,p) level of theory. The calculated results indicate that the mechanisms of the insertion reactions of H2C＝SiLiBr to HF, H2O, and NH3 are identical to each other. The QCISD/6-311＋＋G(d,p)//B3LYP/6-311＋G(d,p) calculated potential energy barriers of the three reactions are 148.62, 164.42, and 165.07 kJ/mol, and the reaction energies for the three reactions are －69.63, －43.02, and －28.27 kJ/mol, respectively. Under the same situation, the insertion reactions should occur easily in the following order H—F＞H—OH＞H—NH2.

Key words: silylenoid H2C＝SiLiBr, RH (R＝F, OH, NH2), insertion reaction, DFT, QCISD