Synthesis,Structure,and Reactions of Heptacoordinate Silicon Compounds Bearing a Novel Tetradentate Ligand

摘要

A trichlorosilane bearing a tetradentate ligand with three coordinating arms was synthesized by the reaction of triarylmethyllithium with tetrachlorosilane.Its heptacoordinate structure around the central silicon atom has been revealed by X-ray crystallographic analysis.Three methoxy oxygen atoms are located at the opposite side to chlorine atoms,and average Si...O interatomic distance is 2.807 A,shorter than the sum of van der Waals radii(Si...O:3.40 A).Chlorine atoms on the central silicon atom were not replaced by any nucleophiles such as alkyllithium,hydride anion,and alcohols.Effective suppression of nucleophilic attack is attr1buted to the intramolecular interactions of lone pairs of oxygen atoms with sigma_(Si-Cl)* anti-bonding orbital as well as steric hindrance.