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

The η3-1,3-bis(silyl)allyllithium [Li{η3-CH(CHSiMe2But)(CHSiMe2R)}(tmen)] (R = But or Me) and 1,3-bis(trimethylsilyl)cyclohexenyllithium [Li{C(SiMe3)CHC(SiMe3)(CH2)2CH2}(tmen)] complexes were obtained by lithiation of the appropriate 1,3-bis(silyl)propene or 1,3-bis(trimethylsilyl)cyclohexene. The lithium complexes were transformed into the potassium complexes [K{CH(CHSiMe2But)2}] or [K{C(SiMe3)CHC(SiMe3)(CH2)2CH2}] by reaction with KOBut. A dimethylsilyl ansa-bridged bis(cyclohexenyl)dipotassium complex [{K2{(η3-C6H4SiMe3-6)2SiMe2}(thf)3}∞] was obtained by a similar route. Single crystal structures of three complexes have been determined.