Insertion of the p-complex structure of silylenoid H2SiLiF into X–H bonds (X = C, Si, N, P, O, S, and F)

The insertion reactions of the p-complex structure (A) of silylenoid H2SiLiF into XHn molecules (X = C, Si, N, P, O, S, and F; n = 1–4) have been studied by ab initio calculations at the G3(MP2) level. The results indicate that the insertion reactions of A into X–H bonds proceed via three reaction paths, I, II, and III, forming the same products, substituted silanes H3SiXHn − 1 with dissociation of LiF, respectively, and all insertion reactions are exothermic. All the seven X–H bonds can undergo insertion reactions with A via path I and II, but only four of them, C–H, Si–H, P–H, and S–H, undergo insertion reactions via path III. The following conclusions emerge from this work: (i) the X–H insertion reactions of A occur in a concerted manner via a three-membered ring transition state; (ii) for path I and II, the stabilization energies of the A–XHn complexes decrease in the order HF > H2O > H2S > NH3 > SiH4 > CH4; (iii) for path I and II, the greater the atomic number of heteroatom (X) in a given row, the easier the insertion reaction of XHn hydrides and the larger the exothermicity, and for the second-row hydrides, the reaction barriers are lower than for the first-row hydrides; (iv) The barriers of path I are lowest in those of three pathways with the exception of A + SiH4 system, which barrier of path III is lowest. Moreover, the present study demonstrates that both electronic and steric effects play major roles in the course of insertion reactions of A into X–H bonds.

The insertion reactions of the p-complex structure of silylenoid H2SiLiF into X–H bonds proceed via three reaction pathways forming the same products, substituted silanes H3SiXHn − 1 with dissociation of LiF, respectively, and all insertion reactions are exothermic.Figure optionsDownload as PowerPoint slide