Theoretical study on the substitution and insertion reactions of silylenoid H2SiLiF with CH3XHn−1 (X = F, Cl, Br, O, N; n = 1, 1, 1, 2, 3)

The substitution and insertion reactions of H2SiLiF (A) with CH3XHn−1 (X = F, Cl, Br, O, N; n = 1, 1, 1, 2, 3) have been studied using density functional theory. The results indicate that the substitution reactions of A with CH3XHn−1 proceed via two reaction paths, I and II, forming the same product H2SiFCH3. The insertion reactions of A with CH3XHn−1 form H2SiXHn−1CH3. The following conclusions emerge from this work. (i) The substitution reactions of A with CH3XHn−1 occur in a concerted manner. The substitution barriers of A with CH3XHn−1 for both pathways decrease with the increase of the atomic number of the element X for the same family systems or for the same row systems. Path I is more favorable than path II. (ii) A inserts into a C–X bond via a concerted manner, and the reaction barriers increase for the same-row element X from right to left in the periodic table, whereas change very little for the systems of the same-family element X. (iii) The substitution reactions occur more readily than the insertion reactions for A with CH3XHn−1 systems. (iv) All substitution and insertion reactions of A with CH3XHn−1 are exothermic. (v) In solvents, the substitution reaction process of A with CH3XHn−1 is similar to that in vacuum. The barrier heights in solvents increase in the order CH3F < CH3Cl < CH3Br < CH3OH < CH3NH2. The solvent polarity has little effects on the substitution barriers. The calculations are in agreement with experiments.