Reactivity of dianionic hexacoordinated silicon complexes toward nucleophiles: a new route to organosilanes from silica

Abstract

A general route for the preparation of organosilanes from silica is described. Depolymerization of silica is easily performed by chelating agents such as catechol in the presence of a base such as sodium methoxide with formation of a monomeric hexacoordinated complex [ S~( O -O~C~H~)~]~-~M + (I). The reaction of an excess of Grignard or organolithium reagent leads to the formation of R4Si or R3SiO-CBH4-(o-OH) depending on the nature of the reagent. Functional organosilanes R3SiX can be prepared in a one-pot reaction from 1. Silane (SiH4) is obtained in quantitative yield under very mild conditions from 1. Interestingly, hypervalent anionic silicon species 1 react efficiently with strong nucleophiles, the products obtained corresponding to the result of a nucleophilic displacement at silicon.

The extension of the mechanistic concept of the nucleophilic catalysis in the silicon chemistry to some reactions of the P(III) center: Analogies between silylation and phosphorylation

“…There is accordingly a full analogy to the formation of the phosphorus-silicon complex 1 of Equation 9. One might speculate that the formation of this complex could give rise to the exchange of substituents between two phosphorus atoms of the complex in analogy to the reaction of Equation 9.…”

Alkaline Earth Metal Template (Cross‐)Coupling Reactions with Hybrid Disila‐Crown Ether Analogues

“…From the perspective of Si−O bond activation, weakening of Si−O bonds is of considerable significance regarding the conversion of silicates to silanes. Especially dicatecholato‐silicate(IV) complexes are frequently used as precursors for either silane synthesis or functionalization of various organic molecules . Most recently, a collaborative research of Ollivier and co‐workers together with Fensterbank and co‐workers demonstrated a new synthesis for ketones, in this context employing acyl chlorides …”

“…Especially dicatecholato-silicate(IV) complexes are frequently used as precursors for either silane synthesis or functionalization of various organic molecules. [35][36][37][38][39][40][41][42][43] Most recently,acollaborative research of Ollivier and co-workerst ogether with Fensterbank and co-workers demonstrated an ew synthesis for ketones,i nt his context employinga cyl chlorides. [44]…”

Synthesis and Linear Optical Properties of Tris(catecholato)metal(III,IV) Complexes with Acceptor‐Substituted Ligands

“…In order to gain thermodynamic stability, we used ligands based on catecholate rather than on phenolate as in Brooker's dye. The metal ions are Al III , [24] Ti IV , [25][26][27] and Si IV [28,29] because these ions are known to form stable complexes with catecholate. The ions also form highly polar bonds to oxygen atoms, which will allow the catecholate to retain most of its anionic electronic structure, which is important in order to serve as a good electron donor in the ligand chromophores.…”