TRIALKYLHYDRIDOALANATES RXR'3-XALH CIRCLE-MINUS [R = CME3, R' = CH(SIME3)2]

The very strong base tert-butyl lithium reacts in the presence of chelating tetramethylethylendiamine with the aluminium organyls Al[CH(SiMe3)2]2CMe3 1 and AI[CH(SiMe3)2](CMe3)2 2 not under proton abstraction from the C-H acidic elementorganic substituent, but under beta-elimination and addition of the thereby formed LiH to the coordinatively unsaturated aluminium atom. Two alanates - [HAl{CH(SiMe3)2}2CMe3]- 3 and [HAl]{CH(SiMe3)2}(CMe3)2]- 4 each with Li(TMEDA)2+ as counterion - were isolated; they exhibit separate anions and cations in solid state as shown by a crystal structure determination on 3. In absence of the chelating amine tert-butyl lithium decomposes under the catalytic effect of the aluminium compound to LiH, which does not add to aluminium and precipitates in a reactive form.