Tetrasupersilyl-tetrahedro-tetragallan ((Bu3Si)-Bu-t)(4)Ga-4 - A tetrahedrane with a very compact Ga-4-tetrahedral skeleton

Reaction of R-2*GaX (R* = Supersilyl Si'Bu-3, X = Cl, Br) with R*Na leads i n heptane at room temperature to the dark blue radical R-2(*.)-GaR* which t ransforms at 100 degrees C in heptane into (Bu3Si.)-Bu-t and dark violet R- 4*Ga-4 (1). According to X-ray structure analysis. 1 contains a very compac t Ga-4 tetrahedron (average Ga-Ga bond length 2.572 Angstrom). With oxygen, the thermo- and water-stable compound 1 reacts under formation of colorles s R-4*Ga4O4 = [R*GaO](4), which after X-ray structure analysis contains a G a4O4 heterocubane. By hydrolysis, tetrameric oxogallane R*GaO transforms in to a tetrameric dihydrooxogallane R*Ga(OH)(2) which, according to X-ray str ucture analysis, forms chains of molecules [R*Ga(OH)(2)](4), held together by water molecules. (C) 1999 Elsevier Science S.A. All rights reserved.