Tetraalkylhydrido‐und Tetraalkylmethyldialuminat(5) mit Aluminium – Aluminium‐Bindung: [R2Al – AlXR2]− {RCH(SiMe3)2; XH, Me}

Tetraalkylhydrido‐and Tetraalkylmethyldialuminate(5) with Aluminium – Aluminium Bond: [R2Al – AlXR2]– {RCH(SiMe3)2; XH, Me} Tetrakis[bis(trimethylsilyl)methyl]dialuminium(4) (1) with an aluminium – aluminium bond reacts with tert1‐butyllithium in the presence of the chelating tetramethylethylenediamine (TMEDA) to give a hydridodialuminate(5) 2 [R2Al – AlHR2]− {RCH(SiMe3)2} by β1‐elimination and addition of the hydride anion to one aluminium atom. By treatment of 1 with methyllithium a similar product is formed containing a methyl group bound to aluminium: [R2A1 – AlMeR2]– 3. As shown by crystal structure determination the aluminium – aluminium bond of both molecules is not bridged. Instead, the compounds contain a saturated, four‐coordinated aluminium neighbouring an unsaturated, threefold coordinated aluminium atom. While in the hydrogen compound 2 the aluminium – aluminium bond length [266.7(3) pm] remains unaffected in comparison to the neutral starting compound 1, it is lengthened in the methyl derivative 3 by 9 pm to 275.2(3) pm probably due to the higher sterical demand of the methyl group.