An unsolvated lithium trihydroaluminate and the correponding trialkynylaluminates supported by an anionic triazacyclononane ligand

Abstract

Reaction of the anionic tacn ligand ((tacn)H = 1,4-diisopropyl-1,4,7-triazacyclononane) with LiAlH4 in THF afforded a dimeric, unsolvated lithium trihydroaluminate, which upon treatment with terminal acetylenes HCCR (R = Ph, SiMe3) yielded the corresponding monomeric trialkynylaluminates in which one acetylide ligand bridges the Li and Al atom at the Cα atom while the two terminal acetylide ligands are coordinated to the Al atom.