New hypersilanides of the earth metals aluminium, gallium, and indium

The dialkylaluminiumchlorides R2AlCl (with R = Me, Et; Me = CH3, Et = C2H5) react with base-free lithium-tris(trimethylsilyl)silanide (Li-Hsi; Hsi = - Si(SiMe3)(3)), forming the pyrophoric dialkyl aluminiumhypersilanides R2Al- Hsi. The methyl compound is dimeric in solid state (triclinic space group P (1) over bar, Z = 1 dimer), as in Al2Me6 the association takes place by tw o Al-Me-Al bridges, forming a centrosymmetric molecule of approximately C-2 h point-symmetry. Contrary to this (Me2GaCl)(2) and Li-Hsi form a mixture o f (MeGa(Hsi)Cl)(2) and [Me3Ga-Hsi]Li. The monochloride again is a centrosym metric, chlorine-bridged dimer (monoclinic space group P2(1)/n, Z = 2 dimer s). The extremely air sensitive gallate can be prepared from GaMe3 and Li-H si (1:1 ratio), as well as the homologous [Me3Ga-Hsi]Na and [Me3Ga-Hsi]K fr om GaMe3 and the corresponding alkalimetal hypersilanides. The 1:1 toluene- solvat of the sodium salt crystallizes in the orthorhombic space group Pbca (Z = 8) with polymeric zig-zag-chains, in which the toluene-capped Na-ions act as GaMe ... Na ... Me2Ga-bridges between [Me3Ga-Hsi](-) anions. The reaction of InCl3 with Li-Hsi (1:3 ratio) mainly gives LiCl, metallic I n and the "dihypersilyl" Hsi-Hsi. Ruby-red (Hsi)(2)In-In(Hsi)(2) could also be obtained in low yield and characterized by X-ray structure elucidation (space group P2(1)/c, Z = 4). The H-1, C-13, Si-29 and Li-7 NMR- and the vibrational spectra of the hyper silanides have been measured and discussed.