Synthesis of organoaluminum chalcogenides [RAl(mu-E)](2) (R = N(SiMe3)C(Ph)C(SiMe3)(2), E = Se, Te) from aluminum dihydride [RAlH(mu-H)](2)

1-Azaallylaluminum dihydride [RAlH(mu-H)](2) (1) (R = N(SiMe3)C(Ph)C(SiMe3) (2)) has been prepared in nearly quantitative yield from the reduction of R AlBr2 with an excess of LiAlH4 in diethyl ether. Reaction of 1 with element al Se or Te in toluene afforded the novel organoaluminum chalcogenide [RAl( mu-E)](2) (E = Se (2); Te (3)) in good yield. The structures of compounds 1 , 2, and 3 in the solid state have been characterized by X-ray diffraction analyses. Compounds 2 and 3 have a dimeric structure featuring three novel fused planar four-membered ring systems with a central Al2E2 core. Based on H-1 and Si-29 NMR data and crystal structural analysis of 2 and 3, an equi librium of the trans and cis isomers in solution is proposed for the two co mpounds due to the relative orientation of the two chelating rings of the b identate R ligands.