Aluminium Hydrazides: Dimeric Bis(tert-butyl)aluminium Hydrazides withSix-Membered Al2N4 and Five-Membered Al2N3 Heterocycles

Abstract

Treatment of the hydrazine adduct (Me3C)2AlCl·NH2NHSiMe3 (2) with n-butyllithium afforded the colorless dialkylaluminium hydrazide (Me3C)2AlN(SiMe3)NH2 (3) by the release of butane and the precipitation of LiCl. Hydrazide 3 gave a dimer in solution and in the solid state. As shown by a crystal structure determination, a six-membered Al2N4 heterocycle with two intact endocyclic N−N bonds was formed by a head-to-tail dimerization. Upon sublimation of 3 in vacuum, a rearrangement was observed which gave an isomeric compound 4 after the migration of a hydrogen atom of a hydrazido ligand. The molecular core of 4 comprises a five-membered Al2N3 heterocycle, in which the Al atoms are bridged by one hydrazido ligand similar to 3. The second ligand, however, has only one nitrogen atom in a bridging position with an exocyclic N−N bond. A similar compound (5) was obtained by the reaction of bis(tert-butyl)aluminium chloride with phenylhydrazine and n-butyllithium.