Studies of aminoboranes. Part II. Pyrolysis of monoalkylamine-boranes: some aminoborane trimers (1,3,5-trialkylcyclotriborazanes) and dimers

Brown, Michael P.; Heseltine, R. W.; Sutcliffe, L. H.

doi:10.1039/j19680000612

Cited by 17 publications

(5 citation statements)

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“…The values observed do not match with the values reported for tert -butyl-borazole ( 1 H, δ 1.36; 11 B, δ 31.0), indicating the possibility of hydrolysis (Supporting Information). , …”

Section: Methodsmentioning

confidence: 69%

Homogeneous Catalytic Reduction of Dioxygen Using Transfer Hydrogenation Catalysts

2007

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Solutions of Cp*IrH(rac-TsDPEN) (TsDPEN = H2NCHPhCHPhN(SO2C6H4CH3)-) (1H(H)) with O2 generate Cp*Ir(TsDPEN-H) (1) and 1 equiv of H2O. Kinetic analysis indicates a third-order rate law (second order in [1H(H)] and first order in [O2]), resulting in an overall rate constant of 0.024 +/- 0.013 M(-2) s(-1). Isotopic labeling revealed that the rate of the reaction of 1H(H) + O2 was strongly affected by deuteration at the hydride position (k(HH2)/k(DH2) = 6.0 +/- 1.3) but insensitive to deuteration of the amine (k(HH2)/k(HD2) = 1.2 +/- 0.2); these values are more disparate than for conventional transfer hydrogenation (Casey, C. P.; Johnson, J. B. J. Org. Chem. 2003, 68, 1998-2001). The temperature dependence of the reaction rate indicated DeltaH = 82.2 kJ/mol, DeltaS = 13.2 J/mol K, and a reaction barrier of 85.0 kJ/mol. A CH2Cl2 solution under 0.30 atm of H2 and 0.13 atm of O2 converted to H2O in the presence of 1 and 10 mol % of H(OEt2)2BAr(F)4 (BAr(F)4- = B(C6H3-3,5-(CF3)2)4-). The formation of water from H2 was verified by 2H NMR for the reaction of D2 + O2. Solutions of 1 slowly catalyze the oxidation of amyl alcohol to pentanal; using 1,4-benzoquinone as a cocatalyst, the conversion was faster. Complex 1 also catalyzes the reaction of O2 with RNH2BH3 (R = H, t-Bu), resulting in the formation of water and H2. The deactivation of the catalyst 1 in its reactions with O2 was traced to degradation of the Cp* ligand to a fulvene derivative. This pathway is not observed in the presence of amine-boranes, which were shown to reduce fulvenes back to Cp*. This work suggests the potential of transfer hydrogenation catalysts in reactions involving O2.

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“…The values observed do not match with the values reported for tert -butyl-borazole ( 1 H, δ 1.36; 11 B, δ 31.0), indicating the possibility of hydrolysis (Supporting Information). , …”

Section: Methodsmentioning

confidence: 69%

Homogeneous Catalytic Reduction of Dioxygen Using Transfer Hydrogenation Catalysts

2007

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“…To probe this, ideally the cyclotriborazane [H 2 BN t BuH] 3 would be reacted with H 2 B]N t BuH. Although the crystal structure of this material has recently been reported [25], it is only produced in low yields from the Al(NMe 2 ) 3 catalyzed dehydrogenation of H 3 B$N t BuH 2 or by pyrolysis of H 3 B$N t BuH 2 [21]. As an alternative [37] we instead used the sterically less encumbered methylsubstituted cyclotriborazane [H 2 BNMeH] 3 , which is readily prepared [38] (2)) [17].…”

Section: Resultsmentioning

confidence: 97%

“…Free H 2 B] N t BuH has not, to our knowledge, been isolated, and its spectroscopic data has only been briefly mentioned as an intermediate in the dehydrogenation of H 3 B$N t BuH 2[12,20]. The cyclic dimer [H 2 BNH t Bu] 2[21] can be heated to generate reactive H 2 B]N t BuH in situ[22]; while the metal-mediated dehydrocoupling of H 3 B$N t BuH 2 has been described [23e25], and in some cases the solid-state structures of the resulting amino-borane coordination…”

mentioning

confidence: 98%

A tert-butyl-substituted amino-borane bound to an iridium fragment: A latent source of free H2BNtBuH

Johnson

Weller

2012

Journal of Organometallic Chemistry

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“…Initial studies of alkylamine borane (H 2 RNBH 3 ) thermolysis (at 90-120 1C) afforded mixtures of cyclic amino-and iminoborane oligomers as well as undefined products. 87 Framery and Vaultier found that heating N-and B-substituted amine boranes (H 2 RNBH 3 or H 3 NBRH 2 ) to 200 1C gave the corresponding borazine compounds in good yield. 65 Detailed studies on the thermolysis of MeAB revealed that hydrogen is released in two stages, one at B100 1C, and the second at 190 1C.…”

Section: Solid State Thermolysismentioning

confidence: 99%

B–N compounds for chemical hydrogenstorage

et al. 2009

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Hydrogen storage for transportation applications requires high volumetric and gravimetric storage capacity. B-N compounds are well suited as storage materials due to their light weight and propensity for bearing multiple protic (N-H) and hydridic (B-H) hydrogens. This critical review briefly covers the various methods of hydrogen storage, and then concentrates on chemical hydrogen storage using B-N compounds. The simplest B-N compound, ammonia borane (H3NBH3), which has a potential 19.6 wt% hydrogen storage capacity, will be emphasised (127 references).

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Studies of aminoboranes. Part II. Pyrolysis of monoalkylamine-boranes: some aminoborane trimers (1,3,5-trialkylcyclotriborazanes) and dimers

Cited by 17 publications

References 0 publications

Homogeneous Catalytic Reduction of Dioxygen Using Transfer Hydrogenation Catalysts

Homogeneous Catalytic Reduction of Dioxygen Using Transfer Hydrogenation Catalysts

A tert-butyl-substituted amino-borane bound to an iridium fragment: A latent source of free H2BNtBuH

B–N compounds for chemical hydrogenstorage

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