Monomeric lithium and sodium silylbenzyl complexes: syntheses, structures, and CO bond olefination.

Herein we report the syntheses, structures and reactivity studies of two new monomeric alkali metal silylbenzyl complexes stabilised by a tetradentate amine ligand, tris[2-(dimethylamino)ethyl]amine (Me6Tren). The two complexes, namely [MR'(Me6Tren)] (R': CH(Ph)(SiMe3)) (2-Li: M = Li; 2-Na: M = Na), exhibit significant different coordination modes according to their metal identity (Li: σ-coordination; Na: π-coordination). Reactivity studies of 2-Li and 2-Na reveal that they are efficient in promoting a widely-used class of organic functional group interconversion: CO bond olefination of ketones, aldehydes and amides, to produce tri-substituted internal alkenes.