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)

Abstract

Abstract The substitution and insertion reactions of H 2 SiLiF ( A ) with CH 3 XH n −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 CH 3 XH n −1 proceed via two reaction paths, I and II, forming the same product H 2 SiFCH 3 . The insertion reactions of A with CH 3 XH n −1 form H 2 SiXH n −1 CH 3 . The following conclusions emerge from this work. (i) The substitution reactions of A with CH 3 XH n −1 occur in a concerted manner. The substitution barriers of A with CH 3 XH n −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 CH 3 XH n −1 systems. (iv) All substitution and insertion reactions of A with CH 3 XH n −1 are exothermic. (v) In solvents, the substitution reaction process of A with CH 3 XH n −1 is similar to that in vacuum. The barrier heights in solvents increase in the order CH 3 F 3 Cl 3 Br 3 OH 3 NH 2 . The solvent polarity has little effects on the substitution barriers. The calculations are in agreement with experiments.