Reduction of silicon halides and alkoxides with diisobutylaluminum hydride. Stereochemistry-rate law correlations for the SNiSi and SN2Si mechanisms

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)

“…family systems or for the same period systems. Consequently, our theoretical results are in complete accord with the Hammond postulate [50], which associates a reactant-like transition state with a smaller barrier.…”

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

“…The process from transition state to intermediate is also that of inversion of the triangular cone ''umbrella'' formed by Si atom and three H atoms, and that of X atom reacting with Si from back of F atom with the departing of F from Si. As a whole, this process is similar to S N 2-Si type nucleophilic substitution mechanism [28]. In XIM1, the Si-X distance has greatly shortened to 1.896 Å (CIM1), 1.761 Å (NIM1), 1.708 Å (OIM1), 1.655 Å (FIM1), and 2.368 Å (SiIM1), 2.303 Å (PIM1), 2.213 Å (SIM1), respectively, which is almost equal to that in corresponding product H 3 SiXH n À 1 , respectively.…”

“…In the region from s = À0.50 to 2.50 (amu) 1/2 bohr, the charges of H 2 Si moiety have increased from À0.002 (s = À0.50) to 0.836 (s = 2.50), and the Si-H* and Si-F* bonds formed with the inversion of configuration of F*SiH 3 moiety. It is reasonable to say that the insertion process involves a S N 2-Si type reaction mechanism [28].…”

Dual Role of Doubly Reduced Arylboranes as Dihydrogen- and Hydride-Transfer Catalysts

“…It has been proposed that the reduction of chlorosilanes with aluminum hydrides involves four-membered Al-H-Si-Cl rings in the transition state . A similar scenario is also conceivable for [ 4 -H 2 ] 2– as the reducing agent.…”