21793-61-3Relevant articles and documents
Heterogeneous dehydrocoupling of amine-borane adducts by skeletal nickel catalysts
Robertson, Alasdair P. M.,Suter, Riccardo,Chabanne, Laurent,Whittell, George R.,Manners, Ian
, p. 12680 - 12691 (2011)
Skeletal Ni, produced by the selective leaching of Al from a Ni/Al alloy, has been successfully employed in the catalytic dehydrogenation of various amineborane adducts. The combination of low cost and facile single-step synthesis make this system a potentially attractive alternative to the previously described precious metal and other first-row metal catalysts. The heterogeneous nature of the catalyst facilitates convenient product purification, and this is the first such system to be based on a first-row transition metal. Catalytic dehydrocoupling of Me2NH·BH3 (1) and Et2NH3 BH3 (5) was demonstrated using 5 mol % skeletal Ni catalyst at 20 °C and produced [Me2N·BH2]2 (2) and [Et2N-BH2]2/Et2NdBH2 (6), respectively. The related adduct iPr2NH3 BH 3 (7) was also dehydrogenated to afford iPr2NdBH2 (8) but with significant catalyst deactivation. Catalytic dehydrocoupling of MeNH2 3 BH3 (9) was found to yield the cyclic triborazane [MeNH-BH 2]3 (10) as the major product, whereas high molecular weight poly- (methylaminoborane) [MeNH-BH2]n (11) (Mw = 78 000 Da, PDI = 1.52) was formed when stoichiometric quantities of Ni were used. Similar reactivity was also observed with NH3 3 BH3 (12), which produced cyclic oligomers and insoluble polymers, [NH2-BH2] xx (14), under catalytic and stoichiometric Ni loadings, respectively. Catalyst recycling was hindered by gradual poisoning. A study of possible catalyst poisons suggested that BH3 was the most likely surface poison, in line with previous work on colloidal Rh catalysts. Catalytic borane adducts using skeletal Cu and Fe was also explored. Skeletal Cu was found to be a less active dehydrogenation catalyst for amine-borane adducts but also yielded poly(methylaminoborane) under stoichiometric conditions on reaction with MeNH2 · BH3 (9). Skeletal Fe was found to be completely inactive towardamine-borane dehydrogenationr
Dehydropolymerisation of Methylamine Borane and an N-Substituted Primary Amine Borane Using a PNP Fe Catalyst
Anke, Felix,Boye, Susanne,Spannenberg, Anke,Lederer, Albena,Heller, Detlef,Beweries, Torsten
supporting information, p. 7889 - 7899 (2020/06/02)
Dehydropolymerisation of methylamine borane (H3B?NMeH2) using the well-known iron amido complex [(PNP)Fe(H)(CO)] (PNP=N(CH2CH2PiPr2)2) (1) gives poly(aminoborane)s by a chain-growth mechanism. In toluene, rapid dehydrogenation of H3B?NMeH2 following first-order behaviour as a limiting case of a more general underlying Michaelis–Menten kinetics is observed, forming aminoborane H2B=NMeH, which selectively couples to give high-molecular-weight poly(aminoborane)s (H2BNMeH)n and only traces of borazine (HBNMe)3 by depolymerisation after full conversion. Based on a series of comparative experiments using structurally related Fe catalysts and dimethylamine borane (H3B?NMe2H) polymer formation is proposed to occur by nucleophilic chain growth as reported earlier computationally and experimentally. A silyl functionalised primary borane H3B?N(CH2SiMe3)H2 was studied in homo- and co-dehydropolymerisation reactions to give the first examples for Si containing poly(aminoborane)s.
Catalytic dehydrogenation of dimethylamine borane by group 4 metallocene alkyne complexes and homoleptic amido compounds
Beweries, Torsten,Hansen, Sven,Kessler, Monty,Klahn, Marcus,Rosenthal, Uwe
, p. 7689 - 7692 (2011/09/20)
Dehydrogenation of Me2NH·BH3 (1) by group 4 metallocene alkyne complexes of the type Cp2M(L)(η2- Me3SiC2SiMe3) [Cp = η5- cyclopentadienyl; M = Ti, no L (2Ti); M = Zr, L = pyridine (2Zr)] and group 4 metal amido complexes of the type M(NMe2)4 [M = Ti (8Ti), Zr (8Zr)] is presented.
