Synthesis and Structures of Solvent-Separated Lithium Zincates of the Type [Li(tmeda)₂]⁺[Me₃_-<i>_n</i>Zn{CH(SiMe₃)Ph}<i>_n</i>]^- (<i>n</i> = 1−3, tmeda = 1,2-Bis(dimethylamino)ethane)

Abstract

The reaction of methyllithium with the tmeda complex of ((trimethylsilyl)benzyl)zinc chloride in the presence of 1,2-bis(dimethylamino)ethane (tmeda) in 2:1 molar ratio quantitatively yields the heteroleptic zincate [Li(tmeda) 2 ] + [Me 3 - n Zn{CH(SiMe 3 }Ph] n ] - ( n = 1, 1 ). Under similar conditions, MeLi and ((trimethylsilyl)benzyl)lithium react with bis((trimethylsilyl)benzyl)zinc to form the zincates with n = 2 ( 2 ) and 3 ( 3 ), respectively. The molecular structures of 1 and 2 show shorter Zn−C bond lengths to the methyl group than to the benzylic substituent.