Synthesis and Structures of Solvent-Separated Lithium Zincates of the Type [Li(tmeda)2]+[Me3 - n Zn{CH(SiMe3)Ph} n ]- (n = 1−3, tmeda = 1,2-Bis(dimethylamino)ethane)

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]+[Me3 - n Zn{CH(SiMe3}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.