On the Gallanyls R*3Ga2· and R*4Ga3· As Well As Gallanides R*3Ga2− and R*4Ga3− (R* = SitBu3) − Syntheses, Characterization, Structures

Abstract

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*]−.

Synthesis and Structures of Polyhedral Hexa‐ and Octagallium Cluster Compounds

“…This is the longest gallium–gallium bond in digallane(4) derivatives, known, which can be as short as 233.1 pm in a tetraamino derivative . With the even more bulky supersilyl group R 2 no digallane(4) was accessible, one R 2 was lost forming the radical Ga 2 (R 2 ) 3 …”

Supersilyltrielane R nEHal3-n (E = Triel, R = SitBu3): Synthesen, Charakterisierung, Reaktionen, Strukturen [1] / Supersilyltrielanes R nEHal3-n (E = Triel, R = SitBu3): Syntheses, Characterization, Reactions, Structures [1]

“…(17) auf dem Wege über Radikale R*2E* zu Ditrielanen R*4E2 um [2,10]. (R*2B* kann -sterisch bedingt -nicht dimeriseren und wird offensichtlich weiter zu R*2B " reduziert; s. oben):…”

“…R%EHal + 2Na^f R f E a :-2Rt ■ R*2E-ER*2 (E = Al, Ga, In, TI) (17) Die betreffenden Ditrielane lassen sich ihrerseits thermisch oder mit NaR* in andere Trielclusterverbindungen umwandeln (bei erhöhter Temperatur oder in Anwesenheit von NaR* entstehen letztere Verbindungen naturgemäß direkt aus R*2EHal). So zerfällt R*4A12 bei 100 °C in Heptan in R*3A1~,*, R*4A13* und R*4A14 [17], R*4Ga2 in Alkanen be reits bei sehr tiefen Temperaturen in R*3Ga2* und dann bei 100 °C in R*4Ga4 [17], sowie R*4In, in Heptan bei 100 °C in R*8In12 [18].…”

“…So zerfällt R*4A12 bei 100 °C in Heptan in R*3A1~,*, R*4A13* und R*4A14 [17], R*4Ga2 in Alkanen be reits bei sehr tiefen Temperaturen in R*3Ga2* und dann bei 100 °C in R*4Ga4 [17], sowie R*4In, in Heptan bei 100 °C in R*8In12 [18]. Auch wandelt sich R*3Ga2* mit NaR* in ein THF-Addukt von NaGa2R *3 um, das in Gegenwart von R*Br in das -unter Bildung von R*4Ga4 und R*6Ga8 thermolysierende [19] -Radikal R*4Ga3* übergeht [17].…”

Synthese und Struktur von N,N′‐Diisopropylamidinat‐substituierten Oligogallanen GanRnI2 (n ≤ 4)

“…In unserer Arbeitsgruppe konnte das erste anionische, lineare [(Ph 3 Ge) 3 Ga–Ga–Ga(GePh 3 ) 3 ] – durch Reaktion von Li(thf) 3 GePh 3 mit „GaI“ hergestellt werden 8. Weniger substituierte Trigallane können Ringe bilden, wie Ga 3 ( t Bu 3 Si) 4 9 oder K 2 Ga 3 Aryl 3 10 (Aryl = 2, 6‐Dimesitylphenyl). Durch die Verwendung von zweizähnigen Substituenten können alkanartige Trigallane erhalten werden: [{CHNdipp} 2 Ga–GaH 2 –Ga{CHNdipp} 2 ] – 11 (dipp = 2, 6‐Diisopropylphenyl), [(nacnac)ClGa–GaCl–GaCl(nacnac)]12 [nacnac = {(dipp)NC(CH 3 )} 2 CH] oder [(nacnac)MeGa–GaMe–GaMe(nacnac)]12.…”