No abstract

Deep violet (tBu3Si)4In2 (1) and black‐green (tBu3Si)4Tl2 (2) are formed from MBr and tBu3SiNa in THF at −78 °C [Eq. (a)]. The M atoms of 1 (decomp. 125 °C) and 2 (decomp. 52 °C) are each coordinated by two Si atoms and one M atom in a trigonal‐planar fashion, and the two Si2MM planes are orthogonal.

Reaction of AlX3 (X = Cl, Br) with R*Na (R* = supersilyl, Si(t-Bu)3) in heptane at room temperature gave the ruby dialane R*2Al−AlR*2 (1). X-ray structure analysis showed it to contain a Si2Al−AlSi2 skeleton with D 2 d symmetry and the longest Al−Al bond to date (2.751(2) Å). Water- and air-sensitive 1 reacts with iodine or hydrogen to form R*2AlI or R*2AlH, respectively. Thermolysis and photolysis transform 1, via [R*2Al−AlR*]•, into the tetraalatetrahedrane Al4R*4.

The reduction of black‐blue tris(supersilyl)digallanyl [R*2Ga−GaR*]· (R* = SitBu3 = supersilyl) in organic solvents with Na, NaC10H8, or NaR* leads to deep‐red sodium tris(supersilyl)digallanide−THF(1/3) NaGa2R*3×3THF = [R*2Ga−GaR*Na(THF)3], which transforms in the presence of 18‐crown‐6 into deep‐blue sodium tetrakis(supersilyl)trigallanide−18‐crown‐6(1/1)−THF(1/2) [Na(18‐C‐6)(THF)2]+[R*2Ga−GaR*−GaR*]−.The oxidation of the latter anion with R*Br or TCNE as well as the reaction of the digallanyl R*3Ga2· with R*Br leads to deep‐green tetra(supersilyl)cyclotrigallanyl [···R*Ga−GaR*2−GaR*···]·. The latter radical thermolizes at 100 °C to dark‐violet tetrakis(supersilyl)‐tetrahedro‐tetragallane R*4Ga4 besides the digallanyl R*3Ga2·. This is also prepared from NaR* and GaCl3 or R*2GaCl, as well as by oxidation of R*3Ga2−, and itself thermolizes with formation of the tetrahedrane R*4Ga4. According to X‐ray structure analyses of the mentioned compounds, the Ga−Ga bond of the digallanide NaGa2R*3×3THF (NMR spectroscopically observed) is comparably short (2.380 Å), approaching a bond order of 2. In fact, it is distinctly shorter than the Ga−Ga bond (2.420 Å) in the digallanyl R*3Ga2· (EPR spectroscopically observed). The Ga atoms of the trigallanyl R*4Ga3· (EPR spectroscopically observed) are located at the corners of a triangle with two shorter R*2Ga−GaR* sides (2.527 Å) and a comparably longer R*Ga−GaR* basis (2.879 Å). The mean value of the two Ga−Ga bonds in the trigallanide R*4Ga3− (NMR spectroscopically observed) is as long (2.53 Å) as the short Ga−Ga bonds in R*4Ga3·. The anion shows an intramolecular CH3···Ga contact (C−Ga 2.10 Å) between one peripheral methyl group of the R*2Ga entity and the anionic Ga atom in [R*2Ga−GaR*−GaR*]−.

3 SiCl. According to X-ray structure analyses, the ditrielanes contain two planar groups R 2 EE which are orthogonal to each other (R = R*; angle REER ca. 90°) or nearly orthogonal (R = RЈ; angle REER ca. 80°). All compounds are deeply colored. The λ max value of the visible absorption shifts with increasing atomic number of E and with the increasing angle between the R 2 EE planes to longer wavelengths (ruby R− besides the mentioned ditrielanes − are presented.In fact, except for the compounds dealt with in this publication, only three other examples of silyl-ditrielanes, namely [(Me 3 Si) 3 Si] 4 E 2 with E ϭ Ga, [9] In, [10] Tl [11] have been published to date. On the other hand, some organyland aminyl-ditrielanes R 4 E 2 are known with R ϭ

The reaction of (AlI·NEt3)4 with donor-free t-Bu3SiNa in toluene at −78 °C leads to the generation and crystallization of Al4[Si(t-Bu)3]4, whichafter Al4Cp*4 is the second structurally characterized Al4R4 compound. The obtained experimental data were compared with results of ab initio calculations.

Water- and oxygen-sensitive compounds R*EHal2•D, R*EHal2 and R*2EHal (R* = SitBu3; E = B, Al, Ga, In, TI; Hal = F, Cl, Br, I; D = OR2, NR3) have been synthesized by reaction of EHal3 with NaR* in the absence or presence of donors as well as by substitution of D, Hal or R* by other substituents, or by reaction of R*2E-ER*2 (E = Al, In) with I2, H2, AgF2 or HBr. Thermal decomposition of the compounds in solution or in the gas phase leads to elimination of D from R*EHal2•D, or of R*Hal from R*EHal2 and R*2EHal, respectively. The dihalides R*EHal2 act as Lewis acids with respect to donors OR2 or NR3 (formation of adducts R*EHal2•D), the monohalides R*2EHal as Lewis bases with respect to acceptors EHal3 (formation of R*2E+ EHal4-). Dehalogenations of R*2EHal and R*EHal2 with alkali metals or NaR* leads to compounds R*4E2 (E = AI, In, Tl), R*3E2• (E = AI, Ga), R*4E3• (E = Al, Ga), R*4E4 (E = AI, Ga), R*6Ga8, R*8In12, (R*2B- ), R*2A- , R*3Ga2-, R*4Ga3-, R*4Ga42-, R*4Tl3Cl, or R*6Tl6Cl2. The structures of R*BBr2•Py, R*AlBr2•NEtMe2, (R*AlClOBu)2, R*2BF as well as R*2ECl (E = B, Al, Ga, Tl) have been determined by X-ray structure analyses.

Disupersilylmetalle (tBu3Si)2Zn (farblos), (tBu3Si)2Cd (blaßgelb), (tBu3Si)2Hg (blaßgelb) und Supersilylmetallhalogenide tBu3SiZnCl(THF) (farblos), tBu3SiCdI (farblos), tBu3SiHgCl (farblos) bilden sich in THF durch Einwirkung von tBu3SiNa auf ZnCl2, CdI2, HgCl2 im Molverhältnis 2 : 1 bzw. 1 : 1. THF läßt sich durch TMEDA unter Bildung von tBu3SiZnCl(TMEDA) (farblos) ersetzen, (tBu3Si)2Zn durch Einwirkung von BiCl3 oder BBr3 in tBu3SiZnCl (farblos) oder tBu3SiZnBr (farblos) umwandeln. Gemäß Röntgenstrukturanalysen sind die Verbindungen (tBu3Si)2M monomer mit linearen SiMSi‐Gerüsten, wogegen tBu3SiZnBr und tBu3SiHgCl tetramer sind, und zwar in ersterem Falle mit regulärem, in letzterem mit ausgeprägt irregulärem kubischem M4X4‐Gerüst. Die Verbindungen sind bis 200°C thermostabil (Ausnahme (tBu3Si)2Cd), photolabil und vergleichsweise stabil gegen Wasser und Sauerstoff. Die Disupersilylmetalle wirken als Quellen für Supersilylradikale tBu3Si (bei Bestrahlung) sowie als milde Supersilanidierungsmittel (z. B. (tBu3Si)2Zn/BBr3 → tBu3SiZnBr/tBu3SiBBr2), die Supersilylmetallhalogenide als Lewis‐Säuren (Bildung von tBu3SiMX · Donor) und Elektrophile (z. B. tBu3SiHgCl/RLi → tBu3SiHgR/LiCl).