1‐Sila‐3‐alumina‐4‐aluminatacyclopentan mit Al–Al‐Bindung und C 2 Al 2 Si‐Heterocyclus

1‐Sila‐3‐alumina‐4‐aluminatacyclopentane with an Al–Al Bond and a C 2 Al 2 Si Heterocycle Tetrakis[bis(trimethylsilyl)methyl]dialuminium(4) ( 1 ) with an aluminium–aluminium bond reacts in the presence of tetramethylethylenediamine (TMEDA) with the sterically highly shielded bases bis(trimethylsilyl)methyllithium or bis(dimethylphosphanyl)methyllithium to yield under deprotonation of a methyl group a carbanionic species, which is stabilized by an interaction with one of the coordinatively unsaturated Al atoms. The five‐membered heterocycle 5 is formed containing two Al, one Si and two C atoms. The Al–Al bond remains uncleaved. Interestingly, 5 crystallizes in different crystals with and without crystal ether, which were both characterized by crystal‐structure determinations. The Al–Al bond length in 5 [264.1(2) and 266.5(3) pm, respectively] is only slightly changed in comparison to the neutral starting compound 1 (266.0 pm). Under similar conditions the sterically less demanding ethyllithium leads to a β‐elimination and addition of the thereby formed LiH to one of the two Al atoms to give the recently published hydridodialuminate(5) Li(TMEDA) 2 + [R 2 Al–AlHR 2 ] – ( 2 ).