Superacidic aluminum azido species: precursors to triazolyl dimers, trimers and tetramers

Abstract

The aluminum-azido species (Me₃SiN₃)Al(C₆F₅)₃ thermally converts to [(C₆F₅)₂Al(μ-N₃)]₂ 2. Further reactions with Me₃SiN₃ afford [(C₆F₅)₂Al(μ-N₃)₂]₃Al which contains unique four Al centers bound to six bridging azides. Compound 2 is shown to be a Lewis superacid both experimentally and theoretically, forming dimeric products in reactions with diphenylphosphine oxide or tetrahydrofuran and a monomeric adduct with an NHC donor. Compound 2 also undergoes “click” reactions with alkynes to give dimeric, trimeric and tetrameric products depending on the nature of the substitution on the alkyne, which demonstrates the ability of the reagent to control the nature of aggregation.