Homo‐ und Hetero‐Metall‐Amide des Tris( tert ‐butylamino)methylsilans – Polycyclen und Cluster mit Li, Na, Mg, Al und Tl

Homo and Hetero Metal Amides of Tris( tert ‐butylamino)methylsilane – Polycycles and Clusters with Li, Na, Mg, Al and Tl The hydrogen atoms attached to nitrogen in tris( tert ‐butyl‐amino)methylsilane ( 1 ) can be substituted by metallic main‐group elements in a quite general way. If 1 is treated with trimethylaluminium apart from the monosubstituted product MeSi( t BuNH) 2 ( t BuNAlMe 2 ) ( 2 ) the trisamide MeSi( t BuNAlMe 2 ) 3 ( 3 ) is obtained. In similar ways complete substitution of the amino hydrogen atoms in 1 yields the compounds MeSi[ t BuNMgN(SiMe 3 ) 2 ] 3 ( 6 ), [MeSi( t BuNLi) 3 ] 2 ( 10 ), and [MeSi( t BuNTl) 3 ] 2 ( 11 ), the later two being dimeric. If methyl‐magnesium iodide is allowed to react with 1 the intermediate MeSi( t BuNMgI) 3 ( 4 ) in some instances can be isolated as the THF adduct or may react with a further equivalent of the Grignard compound to generate the complex [MgI‐(THF) 5 ] + [MeSi( t BuNMgI) 3 CH 3 · THF] – ( 5 ). The aluminium compound 2 has been used to access to heterometallic amides combining aluminium and sodium as in MeSi( t BuNAlMe 2 )( t BuNNa)( t BuNH) ( 7 ) or magnesium and aluminium as in the dimeric compounds [MeSi( t BuNAlMe 2 )( t BuNH)( t BuNMgI)] 2 ( 8 ) and [MeSi( t BuNAlMe 2 )( t BuNH)( t BuNMgMe)] 2 ( 9 ). X‐ray structure analyses reveal 3 (tricyclic SiN 3 Al 3 skeleton with Al – N distances from 2.014 to 2.025 Å), 6 (tricyclic Si‐N 3 Mg 3 skeleton), and 7 [bicyclic SiN 3 AlNa skeleton with Na – N distances of 2.47(1) and 2.52(1) Å] to be monomeric even in the solid state. The compounds 8 and 9 (both pentacyclic with spiro magnesium atoms) form centrosymmetric dimers by Mg – I – Mg and Mg – (CH 3 ) – Mg bridges, respectively. The dimers 10 and 11 are completely different in terms of chemical bonding: while in the lithium compound 10 a centrosymmetric polycycle is formed by principly ionic interactions of the lithium atoms with corresponding nitrogen atoms, the centrosymmetric dimer in 11 is held together by Tl – Tl bonds. The X‐ray structure analysis of 5 reveals the anion containing a Mg‐coordinated CH 3 – .