4731-36-6Relevant academic research and scientific papers
Crystal structures of tris(tert-butyl)boron, -aluminum, -gallium, and -indium: Nonplanarity of the AlC3 skeleton and evidence of inter- and intramolecular agostic or hyperconjugative interactions
Cowley, Andrew R.,Downs, Anthony J.,Marchant, Sarah,Macrae, Victoria A.,Taylor, Russell A.,Parsons, Simon
, p. 5702 - 5709 (2005)
X-ray crystal structures determined at low temperatures (150-220 K) for the tris(tert-butyl) derivatives of boron, aluminum, gallium, and indium (M) reveal essentially monomeric molecular units throughout with consistently longer M-C bonds than in the corresponding monomeric trimethyl derivatives. Comparison of the three structures shows a significant strengthening of intermolecular M...β-CH3 binding in the order M = B ～ Ga a distinctly nonplanar MC3 skeleton with the M atom displaced 0.25 A above the plane of the quaternary C atoms in the case where M = Al. Tilting of the tert-butyl groups about the M-C bonds, which is concerted when M = B or Al, appears to reflect the influence of intramolecular hyperconjugation or agostic bonding.
Exceptionally thermally stable, hydrocarbon soluble Ziegler-type Ir(0) n nanoparticle catalysts made from [Ir(1,5-COD)(μ-O 2C8H15)]2 plus AlEt3: Tests of key hypotheses for their unusual stabilization
Hamdemir, Isil K.,?zkar, Saim,Finke, Richard G.
, p. 333 - 343 (2013)
In recent work we showed that Ziegler-type nanoparticles made from [Ir(1,5-COD)(μ-O2C8H15)]2 plus AlEt3 are an unusually thermally stable (≥30 min at 200 C), hydrocarbon-solvent soluble, high catalytic activity nanoparticle catalyst (I.K. Hamdemir, S. O?zkar, K.-H. Yih, J.E. Mondloch, R.G. Finke, ACS Catal. 2 (2012) 632-641). As such, they are analogous to - and currently the cleanest and best characterized model system for - Ziegler-type nanoparticles made from Co or Ni precatalysts plus AlEt3 which are used industrially to hydrogenate ～1.7 × 105 metric tons of styrenic block copolymers per year (for a review of the area, see W.M. Alley, I.K. Hamdemir, K.A. Johnson, R.G. Finke, J. Mol. Catal.: A Chem. 315 (2010) 1-27). The key question addressed in the present paper is What is the nature of the AlEt3-derived stabilizer species? for the unusually stable and active Ziegler-nanoparticles formed from [Ir(1,5-COD)(μ-O2C 8H15)]2 plus AlEt3. Specifically tested herein are four primary hypotheses for the AlEt3-derived stabilizer(s) in the Ir(0)n Ziegler-nanoparticle system: (i) that the key stabilizer is neutral (i.e., uncharged) aluminum alkyl carboxylates following precedent from the work of Shmidt and Bo?nnemann; (ii) that the key stabilizer is anionic [AlEt3(O2C8H 15)]-; (iii) that a key stabilizer is the AlEt3 (or its derivatives) reacting with the Ir(0)n nanoparticle surface; or (iv) that an important AlEt3-derived stabilizer is AlOAl containing alkylalumoxanes formed from any water present. The results obtained rule out (ii), but provide strong evidence for (iii), as well as evidence consistent with (i) and (iv), as stabilizers in Ziegler-nanoparticles. A pictorial scheme (Scheme 2) is provided as a working hypothesis for the stabilization mode(s) of Ziegler-nanoparticles and as a way to focus and expedite the needed additional composition and structural studies of Ziegler-nanoparticle stabilizers.
Hydroaluinination and hydrogallation of 1,2-bis(trimethylsilylethynyl) benzene: Formation of molecular capsules and C-C bond activation
Uhl, Werner,Hepp, Alexander,Westenberg, Hauke,Zemke, Sarina,Wuerthwein, Ernst-Ulrich,Hellmann, Johannes
, p. 1406 - 1412 (2010/05/01)
Treatment of l,2-bis(trimethylsilylethynyl)benzene with di-tert-butylaluminum and di-tert-butylgallium hydrides afforded the simple addition products 1,2-[(Me3Si)(R2E)C-C(H)] 2C6H4 (R = CMe3; E = Al (1), Ga (2)), which could, not be isolated in a pure crystalline form but have been characterized unambiguously by spectroscopic methods. Addition of the Lewis base ethyldimethylamine initiated condensation reactions which gave cage compounds (3 and 4) by the release of the corresponding tri-tert-butyl element derivatives. These cages contain two aluminum or gallium atoms which are bridged by three l,2-bis(trimethylsilylethenyi)benzene spacers to form molecular capsules. The metal atoms are further coordinated by terminal amino groups. The amino ligands could not be removed from the dialuminum compound 4 without decomposition, but the ligand-free gallium, compound 5 was obtained upon heating of 3 (E = Ga) to 80 °C under vacuum. Thermolysis of the aluminum compound 1 in boiling n-hexane gave a unique reaction by the release of tri-tert-butylaluminum and the formal elimination of trimethylsilylethyne (decarbalumination). The product 6 is dimeric in the solid, state via Al-C-Al bridges and has a pentacyclic molecular structure.
Hydrazine adducts of tri(tert-butyl)aluminum, -gallium and -indium - A systematic approach
Uhl, Werner,Abel, Thomas,Koesters, Jutta,Rogel, Friedhelm
, p. 117 - 123 (2008/10/09)
Treatment of the monomeric trialkylelement compounds Al(CMe 3)3, Ga(CMe3)3, and In(CMe 3)3 with different hydrazines H2N-N(H)R (R = Me, CMe3, C6H5) yielded the corresponding adducts (Me3C)3E ←- NH2-N(H)R, 1 to 9, in almost quantitative yields. All products were characterized by crystal structure determinations and shown to have the NH2 group of the hydrazine ligands attached to the central Group 13 atom. These adducts are excellent starting compounds for the generation of hydrazides by thermolysis with release of butane.
Aluminium and gallium compounds of salicylic and anthranilic acids: Examples of weak intra-molecular hydrogen bonding
Branch,Lewinski,Justyniak,Bott,Lipkowski,Barron
, p. 1253 - 1258 (2007/10/03)
Reaction of M(tBu)3 with anthranilic, salicylic and ortho-toluic acids yields [(tBu)2M(μ-O2CC6 H4-2-NH2)]2, M = Al (1), Ga (2), [(tBu)2Ga(μ-O2CC6 H4-2-OH)]2 (3), and [(tBu)2Ga(μ-O2CC6 H4-2-Me)]2 (4), respectively. Reaction of anthranilic acid with two equivalents of Al(tBu)3 allows for the isolation of (tBu)2Al(μ-O2CC6 H4-2-NH2)Al(tBu)3 (5). Compounds 1-5 have been characterized by NMR and IR spectroscopy, mass spectrometry, and X-ray crystallography. The presence of intra-molecular hydrogen bonding, in compounds 1-3, is probed by the orientation of the aromatic rings. Compound 5 is proposed to be a Lewis acid stabilized complex of the intermediate in the synthesis of compound 1.
