121-43-7Relevant articles and documents
Infrared spectra of B(OMe)3, ClB(OMe)2 and Cl2BOMe species, isolated CH streching frequencies and bond strengths
McKean, D. C.,Coats, A. M.
, p. 409 - 420 (1989)
Infrared spectra in the gas phase are reported over the range 3100-500 cm-1 for species of B(OMe)3, ClB(OMe)2 and Cl2BOMe, with CH3, CD3 and CHD2 substitution.A detailed analysis of νCH and νCD data in all three species of Cl2BOMe yields strong evidence for the presence of three kinds of CH bond, two of them weak and one of them strong.The methyl group is then twisted, probably through 10-20 deg, out of the eclipsed or staggered conformation.The CHD2 spectra of the di and trimethoxy compounds are less susceptible to analysis, but suggest also the presence of two weak and strong bonds, the former increasing in weakness as the number of methoxy groups increases.This is as expected from the increased competition likely between the lone pair electrons for the empty boron orbital.The spectra of the CD3 species permit a clear assignment of νBO, δsCH3, δsCD3 and δasCD3 modes.In Cl(COCH3)2, νsBO lies at 1278 cm-1.
Rehydrogenation of aminoboranes to amine-boranes using H2O: Reaction scope and mechanism
Leitao, Erin M.,Manners, Ian
, p. 2199 - 2205 (2015)
Water has been successfully employed as a reagent with which to rehydrogenate aminoboranes (e.g., iPr2N=BH2, 2,2,6,6-Me4C5H6N=BH2, and also transient Me2N=BH2 derived from 1/2[Me2N-BH2]2) to amine-boranes (e.g., iPr2NH·BH3, 2,2,6,6-Me4C5H6NH·BH3, Me2NH·BH3) in approximately 30 yield. The conversion to amine-boranes from the corresponding aminoboranes using this method represents an example of a metal-free, single-step route for the hydrogenation of the B=N bond. Deuterium labeling studies indicated that the protic hydrogen (N-H) on the rehydrogenated amine-borane was derived from H2O, whereas the third hydridic hydrogen (B-H) on the amine-borane was generated from the formation of a postulated hydride-bridged intermediate H2B(μ-H)(μ-NR2)B(OH)H (R2 = Me2, iPr2, 2,2,6,6-Me4C5H6), which requires a second equivalent of the starting aminoborane, thus explaining the low yield. Formation of insoluble borates (BxOyHz) provides a driving force for the reaction. Significantly, the yield can be increased by adding a sacrificial source of BH3 (e.g., to ca. 53% for BH3·THF) or by adding a separate source of H- (e.g., to ca. 95% for LiBH4) to complement the H+ (from H2O) in a more atom-efficient reaction.
Study of the reaction between boron trifluoride methanol complex and sodium methoxide
Wuke, Lang,Weijiang, Zhang,Jiao, Xu,Lei, Zhang
, p. 1530 - 1540 (2014)
The reaction between boron trifluoride methanol complex and sodium methoxide in methanol solution was investigated using conductivity as the reaction indicator. The reaction conditions were examined and a mechanism of this reaction was proposed. Moreover, proper reaction conditions were proposed for boric acid preparation using this reaction. 2014
Preparation of energetic poly(azolyl)borates as new environmentally benign green-light-emitting species for pyrotechnics
Klapoetke, Thomas M.,Rusan, Magdalena,Sproll, Veronique
, p. 2433 - 2443 (2013)
Three different energetic poly(azolyl)borates, potassium dihydridobis(4-nitroimidazolyl)borate, sodium dihydridobis(4, 5-dinitroimidazolyl)borate, and sodium dihydridobis(3, 4,5-trinitropyrazolyl) borate, were synthesized as starting materials for metal-f
Pseudo Halide Chemistry in Ionic Liquids with Decomposable Anions
Harloff, J?rg,Schulz, Axel,Stoer, Philip,Villinger, Alexander
, p. 835 - 839 (2019)
Several pseudohalide containing ionic liquids with quarternary ammonium counter cations of the general formula [R3MeN]X [R = ethyl (1X), n-butyl (2X) with X– = CN–, N3 –, OCN–, and SCN–] were synthesized by decomposition of the corresponding trialkylammonium methylcarbonate in the reaction with Me3Si–X. We also treated 2CN with OP(OMe)3, yielding [nBu3MeN][O2P(OMe)2] and acetonitrile (Me-CN). The double salt [nBu3MeN]2{[B(OMe)3(CN)](CN)} was obtained from the reaction of 2CN with B(OMe)3, featuring the formation of the monocyanotrimethoxyborate anion, [B(OMe)3(CN)]–, co-crystallized with [nBu3MeN]CN. [nBu3MeN]2{[B(OMe)3(CN)](CN)} was fully characterized including structure elucidation.
Reaction of a 14-vertex carborane with nucleophiles: Formation of nido-C2B12, nido-C2B11, and closo-CB11 carborane anions
Zhang, Jian,Zheng, Fangrui,Chan, Hoi-Shan,Xie, Zuowei
, p. 9786 - 9791 (2009)
Nucleophilic reactions of a 14-vertex closo-carborane are reported. 2, 3-(CH2)3-2,3-C2B12H12 (1) reacts with MeOH at 70 °C to give closo-CB11 anions [1,2-(CH2)3CH(OMe)-1-CB11, H10] - ([2a]-), [1,2-(CH2)3CH(OMe)-1- CB11, H10]- ([2b]- ), and [1,2-(CH2)2CH=CH-1-CB11H10] - ([2c]- ). It is suggested that [2c]- is an intermediate for the isomerizatlon from [2a]- to [2b]- . Treatment of 1 with MeOH/Me3N, 'BuOK or LINMe2 affords nido-C2B12 species [8,9-(CH2) 3-μ-11, 12-(Nu)BH-8,9-C2B11H 11]-(Nu = MeO ([3a]-), BuO ([3b]-), and Me2N ([3c]-)). In the presence of acid such as HCl, anions [3]- are converted to 1. However, [3] undergo deboration reaction, in the presence of bases, to generate a nidO-C2B 11 anion [8, 9-(CH2)38,9-C2B 11H12]- ([4]-) that can also be formed directly from the reaction of 1 with excess CsF or piperidine. Mechanistic studies show that [3a]- is the first intermediate in the reaction of 1 with MeOH and [4]- Is unlikely an intermediate.
Aluminum-Hydride-Catalyzed Hydroboration of Carbon Dioxide
Chia, Cher-Chiek,Teo, Yeow-Chuan,Cham, Ning,Ho, Samuel Ying-Fu,Ng, Zhe-Hua,Toh, Hui-Min,Mézailles, Nicolas,So, Cheuk-Wai
supporting information, p. 4569 - 4577 (2021/04/09)
This study describes the first use of a bis(phosphoranyl)methanido aluminum hydride, [ClC(PPh2NMes)2AlH2] (2, Mes = Me3C6H2), for the catalytic hydroboration of CO2. Complex 2 was synthesized by the reaction of a lithium carbenoid [Li(Cl)C(PPh2NMes)2] with 2 equiv of AlH3·NEtMe2 in toluene at -78 °C. 2 (10 mol %) was able to catalyze the reduction of CO2 with HBpin in C6D6 at 110 °C for 2 days to afford a mixture of methoxyborane [MeOBpin] (3a; yield: 78%, TOF: 0.16 h-1) and bis(boryl)oxide [pinBOBpin] (3b). When more potent [BH3·SMe2] was used instead of HBpin, the catalytic reaction was extremely pure, resulting in the formation of trimethyl borate [B(OMe)3] (3e) [catalytic loading: 1 mol % (10 mol %); reaction time: 60 min (5 min); yield: 97.6% (>99%); TOF: 292.8 h-1 (356.4 h-1)] and B2O3 (3f). Mechanistic studies show that the Al-H bond in complex 2 activated CO2 to form [ClC(PPh2NMes)2Al(H){OC(O)H}] (4), which was subsequently reacted with BH3·SMe2 to form 3e and 3f, along with the regeneration of complex 2. Complex 2 also shows good catalytic activity toward the hydroboration of carbonyl, nitrile, and alkyne derivatives.
Acetate-catalyzed hydroboration of CO2 for the selective formation of methanol-equivalent products
Dagorne, Samuel,Dos Santos, Jo?o H. Z.,Jacques, Béatrice,López, Carlos Silva,Nieto Faza, Olalla,Schrekker, Henri S.,Sokolovicz, Yuri C. A.,Specklin, David
, p. 2407 - 2414 (2020/05/13)
The present study details the use of the acetate anion, an inexpensive and robust anion, as a CO2 hydroboration catalyst for the selective formation, in most cases, of methanol-equivalent borane products. Thus, upon heating (90 °C, PhBr), tetrabutylammonium, sodium and potassium acetate (1, 2 and 3, respectively) effectively catalyze CO2 hydroboration by pinacolborane (pinB-H) to afford CO2 reduction products HOCOBpin (A), pinBOCH2OBpin (B) and methoxyborane (C). In most cases, high selectivity for product C with higher borane loading and longer reaction time with a TON of up to 970 was observed. The reduction catalysis remains efficient at low catalyst loading (down to 0.1 mol%) and may also be performed under solvent-free conditions using salt 1 as a catalyst, reflecting the excellent robustness and stability of the acetate anion. In control experiments, a 1/1 1/pinB-H mixture was found to react fast with CO2 at room temperature to produce formate species [pinB(O2CH)(OAc)][N(nBu)4] (5) through CO2 insertion into the B-H bond. DFT calculations were also performed to gain insight into the acetate-mediated CO2 hydroboration catalysis, which further supported the crucial role of acetate as a Lewis base in CO2 functionalization catalysis by pinB-H. The DFT-estimated mechanism is in line with experimental data and rationalizes the formation of the most thermodynamically stable reduction product C through acetate catalysis.
Ph2PCH2CH2B(C8H14) and Its Formaldehyde Adduct as Catalysts for the Reduction of CO2with Hydroboranes
Ramos, Alberto,Anti?olo, Antonio,Carrillo-Hermosilla, Fernando,Fernández-Galán, Rafael
supporting information, p. 9998 - 10012 (2020/07/24)
We study two metal-free catalysts for the reduction of CO2 with four different hydroboranes and try to identify mechanistically relevant intermediate species. The catalysts are the phosphinoborane Ph2P(CH2)2BBN (1), easily accessible in a one-step synthesis from diphenyl(vinyl)phosphine and 9-borabicyclo[3.3.1]nonane (H-BBN), and its formaldehyde adduct Ph2P(CH2)2BBN(CH2O) (2), detected in the catalytic reduction of CO2 with 1 as the catalyst but properly prepared from compound 1 and p-formaldehyde. Reduction of CO2 with H-BBN gave mixtures of CH2(OBBN)2 (A) and CH3OBBN (B) using both catalysts. Stoichiometric and kinetic studies allowed us to unveil the key role played in this reaction by the formaldehyde adduct 2 and other formaldehyde-formate species, such as the polymeric BBN(CH2)2(Ph2P)(CH2O)BBN(HCO2) (3) and the bisformate macrocycle BBN(CH2)2(Ph2P)(CH2O)BBN(HCO2)BBN(HCO2) (4), whose structures were confirmed by diffractometric analysis. Reduction of CO2 with catecholborane (HBcat) led to MeOBcat (C) exclusively. Another key intermediate was identified in the reaction of 2 with the borane and CO2, this being the bisformaldehyde-formate macrocycle (HCO2){BBN(CH2)2(Ph2P)(CH2O)}2Bcat (5), which was also structurally characterized by X-ray analysis. In contrast, using pinacolborane (HBpin) as the reductant with catalysts 1 and 2 usually led to mixtures of mono-, di-, and trihydroboration products HCO2Bpin (D), CH2(OBpin)2 (E), and CH3OBpin (F). Stoichiometric studies allowed us to detect another formaldehyde-formate species, (HCO2)BBN(CH2)2(Ph2P)(CH2O)Bpin (6), which may play an important role in the catalytic reaction. Finally, only the formaldehyde adduct 2 turned out to be active in the catalytic hydroboration of CO2 using BH3·SMe2 as the reductant, yielding a mixture of two methanol-level products, [(OMe)BO]3 (G, major product) and B(OMe)3 (H, minor product). In this transformation, the Lewis adduct (BH3)Ph2P(CH2)2BBN was identified as the resting state of the catalyst, whereas an intermediate tentatively formulated as the Lewis adduct of compound 2 and BH3 was detected in solution in a stoichiometric experiment and is likely to be mechanistically relevant for the catalytic reaction.
A Versatile NHC-Parent Silyliumylidene Cation for Catalytic Chemo- And Regioselective Hydroboration
Leong, Bi-Xiang,Lee, Jiawen,Li, Yan,Yang, Ming-Chung,Siu, Chi-Kit,Su, Ming-Der,So, Cheuk-Wai
supporting information, p. 17629 - 17636 (2019/11/11)
This study describes the first use of a silicon(II) complex, NHC-parent silyliumylidene cation complex [(IMe)2SiH]I (1, IMe =:C{N(Me)C(Me)}2) as a versatile catalyst in organic synthesis. Complex 1 (loading: 10 mol %) was shown to act as an efficient catalyst (reaction time: 0.08 h, yield: 94%, TOF = 113.2 h-1 reaction time: 0.17 h, yield: 98%, TOF = 58.7 h-1) for the selective reduction of CO2 with pinacolborane (HBpin) to form the primarily reduced formoxyborane [pinBOC(-O)H]. The activity is better than the currently available base-metal catalysts used for this reaction. It also catalyzed the chemo- and regioselective hydroboration of carbonyl compounds and pyridine derivatives to form borate esters and N-boryl-1,4-dihydropyridine derivatives with quantitative conversions, respectively. Mechanistic studies show that the silicon(II) center in complex 1 activated the substrates and then mediated the catalytic hydroboration. In addition, complex 1 was slightly converted into the NHC-borylsilyliumylidene complex [(IMe)2SiBpin]I (3) in the catalysis, which was also able to mediate the catalytic hydroboration.
