An alkylzinc bromide and a lithium alkyldibromozincate containing tris(organosilyl)methyl groups

The lithium reagent (3) reacts with a molar equivalent of anhydrous zinc bromide to give the dimeric compound (2a), in which zinc is four-coordinate. The product from a similar reaction with Li{C(SiMe3)2(SiMe2NPhMe)} is the lithium zincate [Li(THF)2(?-Br)2Zn{C(SiMe3)2(SiMe2NPhMe)}] (4), in which the zinc is only three-coordinate. The crystal structures of 2a and 4 have been determined.