- Rhodium-Catalyzed B-H Bond Insertion Reactions of Unstabilized Diazo Compounds Generated in Situ from Tosylhydrazones
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Although transition-metal-catalyzed B-H bond insertion of carbenes into stable borane adducts has emerged as a promising method for organoborane synthesis, all the diazo compounds used to date as carbene precursors have had an electron-withdrawing group to stabilize them. Herein, we report a protocol for rhodium-catalyzed B-H bond insertion reactions of unstabilized diazo compounds generated in situ from tosylhydrazones. In addition, by using chiral dirhodium catalysts, we also achieved an asymmetric version of the reaction with good to excellent enantioselectivities (up to 98:2 e.r.). This is the first enantioselective heteroatom-hydrogen bond insertion reaction to use unstabilized diazo compounds as carbene precursors. The protocol exhibited good functional group tolerance and could be carried out on a gram scale. It also enabled one-pot transformation of a carbonyl group to a boryl group enantioselectively. The B-H bond insertion products could be easily transformed into chiral alcohols and other widely used organoboron reagents with enantiomeric fidelity.
- Pang, Yue,He, Qiao,Li, Zi-Qi,Yang, Ji-Min,Yu, Jin-Han,Zhu, Shou-Fei,Zhou, Qi-Lin
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supporting information
p. 10663 - 10668
(2018/09/06)
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- Method for the production of amine borane complex (by machine translation)
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The invention belongs to the technical field of material preparation, in particular relates to a method for the production of amine borane complex. This invention adopts the borane amine of the direct reaction of an inert gas stream, by regulating the ratio of the two, the need for further post-processing, to make the final product amine complex and offer. In the reaction process such impurity is introduced into the salt-free, does not use an organic solvent; the use of borohydride such as the reagent to produce the borane, for now the current system, can avoid direct operation of toxic gas borane. The method of the invention is simple in operation, the product has high purity, low cost, and can be continuous large-scale production. At the same time, the method and other way to produce the amine borane complex equipment compatible, production equipment by simple method can be used to adjust the production. (by machine translation)
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Paragraph 0039; 0040
(2017/12/05)
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- Amine-boranes bearing borane-incompatible functionalities: Application to selective amine protection and surface functionalization
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The first general open-flask synthesis of amine-boranes with inexpensive and readily available reagents, such as sodium borohydride, sodium bicarbonate, water, and the desired amines is described. Even amines bearing borane-reactive functionalities, such as alkene, alkyne, hydroxyl, thiol, ester, amide, nitrile, and nitro are well tolerated. Some of these novel amine-boranes represent stable molecules containing potentially incompatible electrophilic and nucleophilic centers in proximity. This convenient scalable synthesis provides a novel class of organic ligands for surface functionalization, as demonstrated by the formation of self-assembled layers of thiol- and alkoxysilane-bearing amine-boranes on gold and silica surfaces, respectively.
- Veeraraghavan Ramachandran,Kulkarni, Ameya S.,Zhao, Yan,Mei, Jianguo
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supporting information
p. 11885 - 11888
(2016/10/09)
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- Electrophilic C-H borylation and related reactions of B-H boron cations
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Catalytic procedures are described for the amine-directed borylation of aliphatic and aromatic tertiary amine-boranes. Sequential double borylation is observed in cases where two or more C-H bonds are available that allow 5-center or 6-center intramolecular borylation. The HNTf2-catalyzed borylation of benzylamine-boranes provides a practical means for the synthesis of ortho-substituted arylboronic acid derivatives, suitable for Suzuki-Miyaura cross-coupling applications.
- Prokofjevs, Aleksandrs,Jermaks, Janis,Borovika, Alina,Kampf, Jeff W.,Vedejs, Edwin
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p. 6701 - 6711
(2014/01/06)
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- Mechanisms of the thermal and catalytic redistributions, oligomerizations, and polymerizations of linear diborazanes
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Linear diborazanes R3N-BH2-NR2-BH 3 (R = alkyl or H) are often implicated as key intermediates in the dehydrocoupling/dehydrogenation of amine-boranes to form oligo- and polyaminoboranes. Here we report detailed studies of the reactivity of three related examples: Me3N-BH2-NMe2-BH3 (1), Me3N-BH2-NHMe-BH3 (2), and MeNH 2-BH2-NHMe-BH3 (3). The mechanisms of the thermal and catalytic redistributions of 1 were investigated in depth using temporal-concentration studies, deuterium labeling, and DFT calculations. The results indicated that, although the products formed under both thermal and catalytic regimes are identical (Me3N·BH3 (8) and [Me2N-BH2]2 (9a)), the mechanisms of their formation differ significantly. The thermal pathway was found to involve the dissociation of the terminal amine to form [H2B(μ-H)(μ-NMe 2)BH2] (5) and NMe3 as intermediates, with the former operating as a catalyst and accelerating the redistribution of 1. Intermediate 5 was then transformed to amine-borane 8 and the cyclic diborazane 9a by two different mechanisms. In contrast, under catalytic conditions (0.3-2 mol % IrH2POCOP (POCOP = κ3-1,3-(OPtBu 2)2C6H3)), 8 was found to inhibit the redistribution of 1 by coordination to the Ir-center. Furthermore, the catalytic pathway involved direct formation of 8 and Me2Ni - BH2 (9b), which spontaneously dimerizes to give 9a, with the absence of 5 and BH3 as intermediates. The mechanisms elucidated for 1 are also likely to be applicable to other diborazanes, for example, 2 and 3, for which detailed mechanistic studies are impaired by complex post-redistribution chemistry. This includes both metal-free and metal-mediated oligomerization of MeNHi - BH2 (10) to form oligoaminoborane [MeNH-BH 2]x (11) or polyaminoborane [MeNH-BH2] n (16) following the initial redistribution reaction.
- Robertson, Alasdair P. M.,Leitao, Erin M.,Jurca, Titel,Haddow, Mairi F.,Helten, Holger,Lloyd-Jones, Guy C.,Manners, Ian
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supporting information
p. 12670 - 12683
(2013/09/23)
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- Catalytic redistribution and polymerization of diborazanes: Unexpected observation of metal-free hydrogen transfer between aminoboranes and amine-boranes
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Ir-catalyzed (20 °C) or thermal (70 °C) dehydrocoupling of the linear diborazane MeNH2-BH2-NHMe-BH3 led to the formation of poly- or oligoaminoboranes [MeNH-BH2]x (x = 3 to >1000) via an initial redistribution process that forms MeNH 2?BH3 and also transient MeNH=BH2, which exists in the predominantly metal-bound and free forms, respectively. Studies of analogous chemistry led to the discovery of metal-free hydrogenation of the B=N bond in the "model" aminoborane iPr2N=BH2 to give iPr2NH?BH3 upon treatment with the diborazane Me3N-BH2-NHMe-BH3 or amine-boranes RR′NH?BH3 (R, R′ = H or Me).
- Robertson, Alasdair P. M.,Leitao, Erin M.,Manners, Ian
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p. 19322 - 19325
(2012/01/13)
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- Structures and aggregation of the methylamine-borane molecules, Me nH3-nN BH3 (n = 1-3), studied by X-ray diffraction, gas-phase electron diffraction, and quantum chemical calculations
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The structures of the molecules methylamine-borane, MeH2 ? BH3, and dimethylamine-borane, Me2HN? BH3, have been investigated by gas-phase electron diffraction (GED) and quantum chemical calculations. The crystal structures have also been determined for methylamine-, dimethylamine-, and trimethylamine-borane, MenH 3-nN ? BH3 (n = 1-3); these are noteworthy for what they reveal about the intermolecular interactions and, particularly, the N-H...H-B dihydrogen bonding in the cases where n = 1 or 2. Hence, structures are now known for all the members of the ammonia- and amine-borane series MenH3-nN?BH3 (n = 0-3) in both the gas and solid phases. The structur al variations and energetics of formation of the gaseous adducts are discussed in relation to the basicity of the Me nH3-nN fragment. The relative importance of secondary interactions in the solid adducts with n = 0-3 has been assessed by the semi-classical density sums (SCDS-PIXEL) approach.
- Aldridge, Simon,Downs, Anthony J.,Tang, Christina Y.,Parsons, Simon,Clarke, Michael C.,et al.
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p. 2231 - 2243
(2009/07/30)
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- Real-time evaluation of aluminum borohydride trimethylamine for aluminum chemical vapor deposition
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The chemical species in gas phase and on the surface of aluminum borohydride trimethylamine (ABHTMA) for aluminum chemical vapor deposition as a function of the hot-wall temperature and the chamber pressure were studied using two kinds of Fourier transfor
- Kang, Sang-Woo,Park, Young-Jae,Kim, Yong-Sung,Shin, Yong-Hyeon,Yun, Ju-Young
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p. H333-H339
(2009/05/30)
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- Molecular structure and dynamics in the low temperature (orthorhombic) phase of NH3BH3
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Variable temperature 2H NMR experiments on the orthorhombic phase of selectively deuterated NH3BH3 spanning the static to fast exchange limits of the borane and amine motions are reported. New values of the electric field gradient (EFG) tensor parameters have been obtained from the static 2H spectra of Vzz = 1.652 (±0.082) × 1021 V/m2 and η = 0.00 ± 0.05 for the borane hydrogens and Vzz = 2.883 (±0.144) × 10 21 V/m2 and η = 0.00 ± 0.05 for the amine hydrogens. The molecular symmetry inferred from the observation of equal EFG tensors for the three borane hydrogens and likewise for the three amine hydrogens is in sharp contrast with the Cs symmetry derived from diffraction studies. The origin of the apparent discrepancy has been investigated using molecular dynamics methods in combination with electronic structure calculations of NMR parameters, bond lengths, and bond angles. The computation of parameters from a statistical ensemble rather than from a single set of atomic Cartesian coordinates gives values that are in close quantitative agreement with the 2H NMR electric field gradient tensor measurements and are more consistent with the molecular symmetry revealed by the NMR spectra.
- Cho, Herman,Shaw, Wendy J.,Parvanov, Vencislav,Schenter, Gregory K.,Karkamkar, Abhijeet,Hess, Nancy J.,Mundy, Chris,Kathmann, Shawn,Sears, Jesse,Lipton, Andrew S.,Ellis, Paul D.,Thomas Autrey
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p. 4277 - 4283
(2009/02/01)
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- Heterogeneous or homogeneous catalysis? Mechanistic studies of the rhodium-catalyzed dehydrocoupling of amine-borane and phosphine-borane adducts
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In depth, comparative studies on the catalytic dehydrocoupling of the amine-borane adduct Me2NH-BH3 (to form [Me 2N-BH2]2) and the phosphine-borane adduct Ph2PH·BH3 (to form Ph2PH-BH 2-PPh2-BH3) with a variety of Rh (pre)catalysts such as [{Rh(1,5-cod)(μ-Cl)}2], Rh/Al2O3, Rhcolloid/[Oc4N]Cl, and [Rh(1,5-cOd)2]OTf have been performed in order to determine whether the dehydrocoupling proceeds by a homogeneous or heterogeneous mechanism. The results obtained suggest that the catalytic dehydrocoupling of Me2NH·BH3 is heterogeneous in nature involving Rh(0) colloids, while that of Ph 2PH·BH3 proceeds by a homogeneous mechanism even when starting with Rh(0) precursors such as Rh/Al2O3. The catalytic dehydrocoupling reactions are thought to proceed by different mechanisms due to a combination of factors such as (i) the greater reducing strength of amine-borane adducts, (ii) the increased ease of dissociation of phosphine-borane adducts, and (iii) phosphine ligation and/or poisoning of active catalytic sites on metal colloids.
- Jaska, Cory A.,Manners, Ian
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p. 9776 - 9785
(2007/10/03)
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- Crown-ether-catalysed synthesis of amine borane and amine trideuterioborane adducts from NaBH4-NaBD4 in ether
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Amine borane and amine trideuterioborane adducts have been obtained in good yield by the crown-ether-catalysed reaction of R3N*HCl with NaBH4 and NaBD4 in ether.The absence of isotopic exchange in the reaction with NaBD4 is demonstrated by IR and 11B and
- Kampel, V.,Warshawsky, A.
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- Metal Tetrahydroborates and Tetrahydroborato Metalates, 15. An 11B and 113Cd NMR Study of MBH4-CdCl2 Systems in Dimethylformamide and the X-Ray Structure of CdCl2 * 2 DMF
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CdCl2 dissociates in dimethylformamide into the species Cd(DMF)62+, CdCl(DMF)5+ and CdCl3- as determined by 113Cd NMR spectroscopy. 11B and 113Cd NMR spectra of MBH4/CdCl2 solutions in this solvent show the presence of complexes - with rapid exchange of BH4- and Cl- at ambient temperature.There is no evidence that Cd(BH4)2 is formed in a metathetical reaction.The crystal structure of CdCl2 * 2 DMF has been determined.It is a coordination polymer containing hexacoordinated Cd atoms with the DMF molecules in cis-position.Coordination of DMF occurs via the carbonyl oxygen atoms.
- Linti, Gerald,Noeth, Heinrich,Thomann, Martina
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p. 1463 - 1471
(2007/10/02)
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- 13C nuclear magnetic resonance studies of aromatic amine-borane adducts
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13C NMR measurements are reported for 22 aromatic amine-borane, 7 aliphatic amine-borane, and 3 aliphatic amine-trimethylborane adducts.Additivity of the substituent effects on the δ 13C values of the aromatic carbon atoms is observed.The δ 13C values are compared with those of the arylamines of arylammonium salts and of corresponding alkyl-substituted benzenes.The δ 13C values for the borane adducts, ammonium salts and hydrocarbons exhibit the same trends.However, in the borane adducts similar to the ammonium salts, part of the shielding of the ortho-carbon atoms is attributed to electric field effects which are much less pronounced in the hydrocarbon analogues.The comparison of δ 13C values of aliphatic amine-borane adducts with those of corresponding hydrocarbons indicates the importance of steric effects.
- Paz-Sandoval, M. A.,Camacho, C.,Contreras, R.,Wrackmeyer, B.
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p. 1331 - 1336
(2007/10/02)
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- Molecular addition compounds. 9. Effect of structure on the reactivities of representative borane-amine complexes in typical reactions such as hydrolysis, hydroboration, and reduction
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A number of borane-amine complexes with widely different structural features in the amine portion was prepared and their reactivities toward typical B-H reactions, such as hydrolysis, hydroboration of 1-octene, and reduction of cyclohexanone, were studied. BH3-amine complexes containing an N-phenyl group are hydrolyzed by neutral hydroxylic solvents, while others require a strong acid medium for the hydrolysis. In hydroboration, BH3-N-phenylamine complexes react rapidly with 1-octene in THF at 25°C, while all other types require refluxing THF or toluene for reaction. Again, BH3-N-phenylamine complexes reduce cyclohexanone in THF at 25°C at reasonable rates, while others require acetic acid solvent or mineral or Lewis acids to achieve the desired reduction. Thus, among such borane-amine addition compounds, the BH3-N-phenylamines emerge as unique hydroborating and reducing agents. The results of the present study provide insights into the mechanisms of the hydroboration and reduction reactions. The rates of hydroboration of alkenes with BH3-amine complexes are inversely related to the stability of the adduct, arguing for a prior dissociation of the adduct, followed by the reaction of BH3 with the alkene. The reduction of cyclohexanone with BH3-amine complex in THF proceeds by an analogous dissociation mechanism. In acetic acid or in the presence of mineral or Lewis acids, a bimolecular attack of the BH3-amine complex on the protonated carbonyl group has been considered to be the most viable mechanistic pathway. However, this does not account for the effect of acids on hydrolytic behavior. Consequently, caution is urged in considering possible interpretation of the acid-enhanced reactions of amine-boranes.
- Brown, Herbert C.,Murray, Leo T.
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p. 2746 - 2753
(2008/10/08)
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- Reaction of tetraborane(10) with trimethylphosphine in tetrahydrofuran
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When tetraborane(10) was treated with trimethylphosphine in a 1:1 molar ratio in tetrahydrofuran at -90 to -70°C, (CH3)3P·BH3, THF·B3H7, and H2B(THF)2+B3H8 - were produced. The formation of (CH3)3P·B3H7 was minimal. The same reaction was performed in dimethyl ether, diethyl ether, and dichloromethane, and the patterns of product distribution were compared with each other. The previously proposed mechanism for the B4H10 cleavage reactions was used to explain the observed results by taking the effects of concentrations and strength of the reacting bases into consideration. This mechanistic model explained also the results of the reactions of B4H10 with trimethylamine and phosphine in tetrahydrofuran. The values of 4 ± 1 and 0.41 ± 0.02 were obtained as the equilibrium constants for (CH3)3P·BH3 + THF·B3H7 ? THF·BH3 + (CH3)3P·B3H7 at 25°C and H3P·BH3 + THF·B3H7 ? THF·BH3 + H3P·B3H7 at 0°C, respectively.
- Shimoi, Mamoru,Kodama, Goji
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p. 3300 - 3304
(2008/10/08)
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- A mechanistic model for the reactions of ammonia and the methylamines with phosphine-borane
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When H3PBH3 is dissolved in liquid ammonia at -45° and allowed to stand, the final product is the ionic solid, [NH4][H2P(BH3)2]. At temperatures above -45° increasing amounts of the covalent ammonia-borane, H3NBH3, are formed along with the ionic product, [NH4][H2P(BH3)2]. Methylamine and dimethylamine behave quite differently. At temperatures of -45° and below only the covalent amine-borane, [CH3H2NBH3] or [(CH3)2HNBH3], is obtained as a product. At temperatures above -45° increasing amounts of the ionic product, [CH3NH3][H2P(BH3)2] or [(CH3)2N-H2][H2P(BH 3)2], are found in the amineborane. It is significant that temperature effects are completely reversed in these two systems. Finally (CH3)3N gives only the covalent base addition compound, (CH3)3NBH3, under all conditions studied. A mechanistic model dealing with the anion H2PBH3- is advanced to interpret the above observations. Copyright 1976 by the American Chemical Society.
- Dietz Jr., Edward A.,Morse, Karen W.,Parry, Robert W.
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- Alkali metal reductions of some trimethylamine-haloboranes and bis(trimethylamine)dihydroboronium iodide
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Trimethylamine-bromoborane and trimethylamine-iodoborane were reduced with Na-K alloy in several solvents. The data obtained support the contention that a reactive intermediate, [(CH3)3NBH2:]-, was produced which reacts via two paths, in varying degrees of significance, depending on the solvent used. The synthesis of (CH3)3NBD2H was demonstrated. The synthesis of 1,1,3,3-tetramethyl-1,3-diazonia-2,4-diboratocyclopentane was improved. An improved synthesis for 1,1,4,4-tetramethyl-1,4-diazonia-2,5-diboratocyclohexane was also found.
- Gragg,Ryschkewitsch
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p. 1209 - 1212
(2008/10/08)
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- Cyclic borane derivatives of amino acids
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New five- and six-member heterocycles which are formally cyclized amino acid boranes have been characterized as air-stable volatile solids. The markedly different hydrolysis rates for the two five-membered heterocycles is interpreted as arising from diffe
- Miller, Norman E.
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p. 1459 - 1467
(2008/10/08)
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- The reaction of diborane with trimethylamine-alane and dimethylaminoalane
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Diborane adds to trimethylamine-alane in toluene or diethyl ether to produce (CH3)3N · Al(BH4)3. The action of excess diborane in toluene establishes an equilibrium competition between aluminum borohydride and d
- Keller, Philip C.
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p. 256 - 258
(2007/11/06)
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- Preparation of trialuminum triboron heptakis(dimethylamino)pentahydride
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Treatment of bis(trimethylamine)-alane, [(CH3)3N]2AlH3, with tetrakis(dimethylamino)diborane(4), [(CH3)2N]4B2, results in the formation of the following known compounds: H2, (CH3)3N, [(CH3)2NBH2]2, [(CH3)2N]2BH, and (CH3)3NBH3. In addition, a new species was prepared, Al3B3[N(CH3)2]7H 5, which most likely contains three B-Al bonds. Characterization of this new compound is discussed.
- Hall,Schram
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p. 270 - 274
(2008/10/08)
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- Lewis acid-base reactions among dimethylaminoboron hydrides
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The dimethylaminoboron hydrides related to diborane form a system of Lewis acids and bases, the interconversion of which can be described as addition or removal of BH3 groups. The first-stage action of [(CH3)2N]3B to remove BH3 from (CH3)3N· BH3 is not appreciably reversible, but the second stage, in which [(CH3)2N]2BH and (CH3)3N·BH3 form 2(CH3)2NBH2 and (CH3)3N, is reversible with ΔF° = 13.95 - 0.0330T kcal. Our base·(CH3)2NB2H5 adducts show vapor-phase dissociation increasing in the order pyridine, (CH3)3P, 2-methylpyridine, (CH3)3N; and (CH3)2PH·(CH3)2NB 2H5 fails to exist in the vapor phase but forms a partially dissociated liquid. All five of these adducts on heating react further to form (CH3)2NBH2 and base·BH3, without reversal. The adducts CH3PH2·(CH3)2NB 2H5 and (CH3)2PCF3·(CH3) 2NB2H5 are still more easily dissociated, and their conversion to BH3 complexes and (CH3)2NBH2 is reversible with ΔF° = 10.61 - 0.0268T and 6.59 - 0.01943T kcal., respectively. It is quite apparent that diborane is a much stronger Lewis acid than (CH3)2NB2H5.
- Burg, Anton B.,Sandhu, Jagtar S.
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p. 1467 - 1472
(2008/10/08)
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- Chemistry of boranes. XV. Synthesis of diborane from boric oxide
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A direct synthesis of diborane from boric oxide has been achieved by hydrogenation of the oxide in the presence of aluminum and aluminum trichloride. Very pure diborane is obtained from this reaction in 40-50% conversions at temperatures above 150° and hydrogen pressures of 750 atm. This hydrogenation is believed to proceed through an aluminum chlorohydride intermediate. Amine boranes, aminoboranes, and borazines were obtained directly from boric oxide when the hydrogenation was effected in the presence of secondary or tertiary alkylamines.
- Ford,Kalb,Mcclelland,Muetterties
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p. 1032 - 1035
(2008/10/08)
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- The amine complexes of aluminum hydride. V. Hydrido aluminum borohydride derivatives
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A series of compounds H3-xAl(BH4)x·N(CH3) 3 (x = 1, 2, and 3) and H2-xAl(BH4)xN(CH3)2 (x = 1 and 2) were prepared by a metathetical reaction between LiBH4 and the corresponding chloro derivatives. Their properties and reactions with trimethylamine and mercuric chloride are discussed.
- Ruff, John K.
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p. 515 - 519
(2008/10/08)
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