Synthesis and structures of some silylallyl-lithium or -potassium complexes

The eta(3)-1,3-bis(silyl)allyllithium [Li{eta(3)-CH(CHSiMe2But)(CHSiMe2R)}( tmen)](R = Bu-t or Me) and 1,3-bis(trimethylsilyl)cyclohexenyllithium [Li{C (SiMe3)CHC(SIMe3)(CH2)(2)CH2}(tmen)] complexes were obtained by lithiation of the appropriate 1,3-bis(silyl)propene or 1,3-bis(trimethylsilyl)cyclohex ene. The lithium complexes were transformed into the potassium complexes [K {CH(CHSiMe2Bu(t))(2)}] or [K{C(SiMe3)CHC(SiMe3)(CH2)(2)CH2}]by reaction wit h KOBut. A dimethylsilyl ansa-bridged bis(cyclohexenyl)dipotassium complex [{K-2{(eta(3)-C6H4SiMe3-6)(2)SiMe2}(thf)(3)}(infinity)] was obtained by a s imilar route. Single crystal structures of three complexes have been determ ined.