Synthesis and characterization of tris(trimethylsilyl)methylaluminum chalcogenides [RAl(mu(3)-E)](4) (R = (Me3Si)(3)C; E = Se, Te) and 1-azaallylgallium chalcogenides [R ' Ga(mu(2)-E)](2) (R ' = (Me3Si)(2)C(Ph)C(Me3Si)N; E =S, Se, Te)

Tris(trimethylsilyl)methylaluminum dihydride, (Me3Si)(3)CAlH2. THF (1), has been prepared by the reaction of RLi . 2THF (R = (Me3Si)(3)C) with H3Al . NMe3. The reaction of 1 with elemental Se or Te in toluene afforded the nov el organoaluminum chalcogenide heterocubane [RAl-(mu3-E)](4) (E = Se (2), T e (3)) in good yield. [R ' GaH(mu -H)](2) (4) (R ' = (Me3Si)(2)C(Ph)C( Me3S i)N) was obtained by the reaction of R ' Li . THF with H3Ga . NMe3 and comp ounds 5-7 by the reaction of [R ' GaH(mu -H)](2) with S (5) and RGaCl2 with (Me3Si)(2)E (E = Se (6), Te (7)). The structures of 6 and 7 have been esta blished by X-ray crystallography. Compounds 6 and 7 have a dimeric structur e featuring fused planar four-membered ring systems with a central Ga2E2 co re. On the basis of H-1 and Si-29 NMR data of 6 and 7, the trans and cis is omers could not be confirmed due to the formation of several species in sol ution.