Synthese eines funktionalen Aluminiumalkinids, Me3C-C≡C-AlBr2, und dessen Reaktionen mit der sperrigen Lithiumverbindung LiCH(SiMe3)2†

Synthesis of a Functional Aluminium Alkynide, Me3C-C≡C-AlBr2, and its Reactions with the Bulky Lithium Compound LiCH(SiMe3)2 Treatment of aluminium tribromide with the lithium alkynide (Li)C≡C-CMe3 afforded the aluminium alkynide Me3C-C≡C-AlBr2 (1) in an almost quantitative yield. 1 crystallizes with trimeric formula units possessing Al3C3 heterocycles and the anionic carbon atoms of the alkynido groups in the bridging positions. A dynamic equilibrium was determined in solution which probably comprises trimeric and dimeric formula units. Reaction of 1 with one equivalent of LiCH(SiMe3)2 yielded the compound [Me3C-C≡C-Al(Br)-CH(SiMe3)2]2 (2), which is a dimer via Al-C-Al bridges. Two equivalents of the lithium compound gave a mixture of four main-products, which could be identified as 2, Li[Me3C-C≡C-Al{CH(SiMe3)2}3] (3), Me3C-C≡C-Al[CH(SiMe3)2]2 (4), and Al[CH(SiMe3)2]3. The lithium atom of 3 is coordinated by the C≡C triple bond and an inner carbon atom of one bis(trimethylsilyl)methyl group. Further interactions were observed to C-H bonds of methyl groups.