Trimethylamine Borane Research Articles

Characterization of Boron Carbonitride (BCN) Thin Films Deposited by Radiofrequency and Microwave Plasma Enhanced Chemical Vapor Deposition

Boron carbonitride (BCN) thin films with a thickness of ~4 µm were synthesized on Si (100) substrate by radiofrequency and microwave plasma enhanced chemical vapor deposition using trimethylamine borane [(CH3)3N.BH3)] as a molecular precursor. The microstructures of the films were evaluated using field emission scanning electron microscopy (FE-SEM) and X-ray diffractometry (XRD). Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were used to analyze the chemical bonding state and composition of the films. It has been observed that the films were adhered well to the silicon substrate even after being broken mechanically. XRD and FESEM results showed that the films were x-ray amorphous, rough surface with inhomogeneous microstructure. The micro hardness was measured by nano-indentation tester and was found to be approximately 2~7 GPa. FT-IR suggested the formation of the hexagonal boron carbonitride (h-BCN) phase in the films. Broadening of the XPS peaks revealed that B, C and N atoms have different chemical bonds such as B-N, B-C and C-N. The impurity oxygen was detected (13~15 at.%) as B-O and/or N-O.

Catalytic performance of plate-type Pd/Zn-based catalysts for steam reforming of methanol, prepared by electroless plating

Abstract It has been reported that a Pd/ZnO catalyst, which consists of palladium and zinc oxide, shows high performance in steam reforming of methanol. By processing this granular catalyst into a plate-type catalyst, a hybrid wall-type methanol reformer with high heat resistance and high reforming performance would be constructed. In this study, such a plate-type Pd-ZnO catalyst was prepared on an aluminum substrate by electroless plating, which consisted of a displacement plating of zinc and a chemical reduction plating of palladium. The catalytic properties of the prepared Pd-ZnO catalyst for steam reforming of methanol were then investigated. The reforming properties of the prepared catalyst varied depending on the reducing agent used in the palladium plating. The plate-type catalyst prepared with a trimethylamine-borane (TMBA) as the reducing agent exhibited high reforming properties. The measurements of physicochemical properties for such plated layer proved that a PdZn alloy was formed on the surface layer. The PdZn alloy, which was thought to be the active-site of methanol reforming, formed in the plated layer when a continuous treatment of hydrogen reduction followed by oxidation was carried out prior to the reaction. In contrast, when either reduction or oxidation treatments individually were carried out prior to the reaction, little PdZn alloy was formed. The continuous treatment of hydrogen reduction followed by oxidation was thought to be an important operation in proceeding the reforming activity. In addition, the durability in reforming properties of the prepared Pd-ZnO catalyst was examined at 350 °C. The prepared catalyst was less prone to deterioration, and restored and progressed its initial performance when a reoxidation treatment was carried out on the deteriorated surface.

Chemical bonding in carbonitride nanolayers

First results are presented for the identification of chemical bonds and structures (speciation) in boron and silicon carbonitrides, produced as layers of some hundred nm. The boron carbonitride (BC x N y ) films are synthesized by low-pressure chemical vapor deposition (LPCVD) using the precursor substance trimethylamine borane. The samples of silicon carbonitride (SiC x N y ) films are synthesized by plasma-enhanced chemical vapor deposition (PECVD) using hexamethyl disilazane. The measurements were performed by total reflection X-ray fluorescence analysis combined with near-edge X-ray absorption fine structure investigations (TXRF-NEXAFS) and by X-ray photo-electron spectroscopy (XPS). The results are compared with those obtained for standard samples boron carbide (B 4C), boron nitride (e.g., h-BN, c-BN), silicon carbide (SiC), and silicon nitride (Si 3N 4).

NMR Relaxation Time Simulation for Different Models of Motion in (CH3)3NBH3

Monte Carlo simulations of complex rotation of single −CH3 groups, −(CH3)3 groups and −BH3 groups were performed for trimethylamine borane (CH3)3NBH3. In the course of these simulations the correlation functions for different models of rotation were determined. Knowledge of these functions and of some data extracted from NMR experiments allowed for the calculation of the longitudinal magnetic relaxation time T1 as a function of temperature. The values of relaxation times obtained from Monte Carlo simulations are compared to experimental results published by other authors. There is a clear relation between the assumed model of rotation and the shape of the T1 curve versus temperature.

Simulation of the NMR Second Moment as a Function of Temperature in the Presence of Molecular Motion. Application to (CH3)3NBH3

The method for simulating the second moment of the NMR absorption spectrum as a function of temperature is presented. The second moment is first calculated as a function of the number of jumps of rotating molecules or their parts (like methyl groups). This number of jumps is rescaled into the frequency of internal rotation and these frequencies are recalculated into equivalent temperatures. The relation between frequency of rotation, and temperature is established on the basis of the Arrhenius relation υc= υo exp (-Ea/RT). The described method is then applied to the analysis of molecular motion in trimethylamine borane (CH3)3NBH3. The proposed method is especially useful in the case of complex structures, where combined motions are possible, because the NMR second moment is much more sensitive to the geometry of motion than the magnetic relaxation times T1 or T1p usualy used in studies of the internal dynamics of solids.

The structure study of boron carbonitride films obtained by use of trimethylamine borane complex

Diffraction of synchrotron radiation (SR) was used to investigate crystalline structure and phase composition of thin films (1500–5000 Å) of boron carbonitride. These films were synthesized by plasma-enhanced chemical vapor deposition using nontraditional volatile single source precursor trimethylamine borane complex (CH3)3N·BH3 and its mixture with ammonia. The effect of the gas ratio and substrate temperature on chemical and phase composition as well as the structure of the films were investigated. The XRD peculiarities of texture films and ways of increasing sensibility of measurements were considered. A possibility of the information density rise of the thin film XRD was shown due to application of different methods for recording diffraction patterns.

ＣｏＮｉＦｅ電析膜の磁気特性

The magnetic properties of electroplated CoNiFe films were investigated. Anomalous codeposition (suppression of Ni deposition) was observed in the CoNiFe electroplating process. Co74Ni17Fe9 films showed high saturation magnetization (1.8 T), low coercivity (< 1.0 Oe), and low magnetostriction (+4 × 10-6). The coercivity of CoNiFe films was decreased by addition of trimethylamine-borane (TMAB) to the bath, because this decreased their grain size. Co74Ni21Fe5 films with lower magnetostriction (+1 × 10-6) and low coercivity (< 1.0 Oe) were obtained by addition of TMAB to the bath. The resistivity and coercivity was unchanged after annealing at 300°C. The corrosion rates of CoNiFe films and TMAB-CoNiFe in a saturated NaCl solution were also investigated.

Preparation of a new thermo‐responsive adsorbent with maltose as a ligand and its application to affinity precipitation

A thermo-responsive polymer on which maltose was covalently immobilized as an affinity ligand was newly synthesized for purification of thermolabile proteins from the crude solution by affinity precipitation. Among the thermo-responsive polymers synthesized as carriers for adsorbent, poly(N-acryloylpiperidine)–cysteamine (pAP) has a lower critical solution temperature (LCST) of around 4°C, at which its solubility exhibits a sharp change. Adsorbent for affinity precipitation was prepared by combining pAP with maltose using trimethylamine–borane as a reducing reagent. This adsorbent (pAPM) obtained showed a good solubility response: pAPM in the basal buffer (pH 7.0) became soluble below 4°C and was completely insoluble above 8°C. The affinity precipitation method using pAPM consisted of the following four steps: adsorption at 4°C, precipitation of the complex at 10°C, desorption by adding the desorption reagent at 4°C, and recovery of a target protein at 10°C. In the affinity precipitation of Con A from the crude extract of jack bean meal, 82% of Con A added was recovered with 80% purity by addition of 0.2 M methyl-α-D-mannopyranoside as a desorption reagent. In the repeated purification of Con A from the crude extract, pAPM could be satisfactorily reused without decrease in the affinity performance. Moreover, when pAPM was used for the purification of thermolabile α-glucosidase from the cell-free extract of Saccharomyces cerevisiae, 68% of total activity added was recovered and the specific activity per amount of protein of the purified solution was enhanced 206-fold higher than that of the cell-free extract without thermal deactivation of the enzyme. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 568–579, 1998.

Sheldon Shore, Small Boranes, and Ammonia

Although trimethylamine [(CH3)3N] and ammonia [H3N] are both recognized as classic Lewis bases, their reactions with classic Lewis acid borane [BH3 from diborane] was very different. Trimethylamine gave expected trimethylamine borane [(CH3)3NBH3] while ammonia gave a product called the diammoniate of diborane. Its structure was shown to be [H2B(NH3)2]+[BH4]- in late nineteen fifties. The Compound [H2B(NH3)2]+[BH4]- can be viewed as a classic coordination compound in which four-coordinate boron +3 ions are coordinated to hydride ion and ammonia molecule as ligands. It is noted that CoCl2 reacts with (CH3)3N and with NH3 in different ways. The anomaly is in bases, not borane acid. The paper discusses early studies on the diammoniate of diborane and emphasizes how continuing work done by Sheldon Shore at Ohio State University extended work on boranes and answered here-to-fore vexing structural problems on intermediates in borane and borane-ammonia system. His work made major contributions to synthesis. He worked out techniques to prepare significant quantities of pure [H2B(NH3)2][BH4] and of pure H3NBH3. He also prepared fascinating, theoretically anticipated compounds K2BH3 and K2B2H6. The story, as told, shows how a brilliant, imaginative, and thoughtful person, using superb experimental techniques, has been able to develop a difficult experimental system from black art to sound science. Note: This article was prepared from a talk given by author at a Symposium (8/23/95) honoring Sheldon G. Shore on his sixty-fifth birthday. Dr. Shore is Charles H. Kimberly Professor of Chemistry at Ohio State University.

Hydrolysis of trimethylamine borane in the presence of liquid and solid (polymeric) acids

The mechanism of trimethylamine borane (TMAB) hydrolysis in the presence of sulfonate cation exchanger in H +-form, H 2SO 4 and trimethylamine deuterosulfate has been established. The hydrolytic reaction is first order in TMAB when carried out in the presence of polymeric acid. The rate of TMAB hydrolysis is directly proportional to the cation exchange capacity of the resin. It was also established that the resin phase acts as a suppressor of TMAB hydrolysis. For the first time, it was noted that TMAB hydrolysis may be carried out when trimethylamine (TMA) is applied as a hydrolyzing agent. The initial effective rate of hydrolytic reaction in this case is much higher than that observed in sulfuric acid solution. Most importantly, the complete absence of isotope exchange between nitrogen-bound deuterium ions of TMA and hydride hydrogens of TMAB in alkaline and neutral media has been observed.

Hydrolysis of trimethylamine borane in the presence of liquid and solid (polymeric) acids

The mechanism of trimethylamine borane (TMAB) hydrolysis in the presence of sulfonate cation exchanger in H +-form, H 4S0 4 and trimethylamine deuterosulfate has been established. The hydrolytic reaction is of the first order in TMAB when carried out in the presence of polymeric acid. The rate of TMAB hydrolysis is directly proportional to the cation exchange capacity of the resin. It was also established that the resin phase acts as a suppressor towards TMAB hydrolysis. For the first time, it was noted that TMAB hydrolysis may be carried out when trimethylamine (TMA) is applied as a hydrolyzing agent. The initial effective rate of hydrolytic reaction in this case is much higher than that observed in sulfuric acid solution. Most importantly, the complete absence of isotope exchange between nitrogen-bound deuterium ions of TMA and hydride hydrogens of TMAB in alkaline and neutral media has been observed.

Dopant incorporation mechanisms during the growth of thin film diamond

The reactions of boron trichloride and a trimethylamine borane complex have been studied on polycrystalline diamond surfaces. BCl3 is seen to reversibly adsorb with no thermal route for the formation of atomic boron on the diamond surface being apparent; it does, however, have an appreciable surface lifetime (100 ms at 1000 K) allowing bombardment from electrons, ions or atomic hydrogen to cause decomposition. Conversely, the novel precursor compound (CH3)NBH3 is seen to thermally dissociate giving rise to fully volatile reaction by-products and hence offers the potential for low contamination in-situ diamond doping.

トルメチルアミンボランを還元剤とする無電解パラジウムめっき皮膜の結晶構造

This report describes the crystal structure of and heat-induced structural changes in electroless palladium plating films deposited from an ethylenediamine complex bath using trimethylamine borane as a reducing agent. The boron content of the films and their crystallinity were proportional to the concentration of trimethylamine borane in the bath. X-ray diffraction data showed a diffused pattern, in as-plated films (before heat-treatment), which changed into the sharp crystalline features of PdH0.706 at 400°C, and the sharp crystalline features of the Pd phase after heat-treatment at 600°C. The diffraction angle of the Pd phase shifted to a slightly lower angle following an increase in boron content.

トリメチルアミンボランを還元剤とする無電解パラジウムめっきの物質収支および析出機構

The deposition mechanism in palladium electroless plating from ethylenediamine complex solutions containing trimethylamine borane (TMAB) as a reducing agent was investigated.The TMAB utilization factor was found to be 68% to 86% for palladium deposition and 25% to 32% for boron deposition. The deposition mechanism can be explained by the electrochemical mechanism, based on the following reactions.Local anodic reaction(CH3)3NBH3+2H2O→(CH3)3N+BO2-+7H+6e-Local cathodic reactionPd2++2e-→PdmPd2++(CH3)3NBH3+(2m-3)e-→PdmB+(CH3)3N+3H+

Facile Preparation of 1,6-Anhydro-2-azido-3-O-benzyl-2-deoxy-β-d-glucopyranose and Its 4-O-Substituted Derivatives

Abstract Treatment of 1,6-anhydro-2,3-O-endo-benzylidene-β-d-mannopyranose derivatives with trimethylamine–borane (1/1)–aluminium chloride resulted in highly regioselective fission of the cyclic acetals to give the corresponding 2-O-unprotected-3-O-benzyl derivatives. Trifluoromethanesulfonylation of these, followed by nucleophilic substitution, afforded 2-azido-2-deoxy derivatives in good yields.

Aqua-impregnated resins: hydrogen-deuterium exchange on trimethylamine borane in an ion-exchange column

The hydrogen-deuterium (H-D) exchange reaction between trimethylamine borane (TMAB) and deuterium oxide taken up by a sulfonate cation exchanger, Dowex 50-X2 in the D + form, was carried out in columns under dynamic conditions. A first pass of a 0.1 M solution of TMAB through a Dowex 50-X2 ion exchanger, swollen in D 2O, gives > 90% conversion into TMAB-d 3. A second pass of the enriched solution through a fresh resin produces 100% pure deuterated product zone. Kinetic studies of consequential deuteration of 0.1 M TMAB solutions in CCl 4 with Dowex 50-X2 in the D + form under batch conditions show that the effective rate of isotope exchange is directly proportional to the relative amount of D 2O in the resin phase.

Hydrolysis of (trimethylamine)borane with ion-exchange resins: effect of ionic surfactants

The hydrolysis of (trimethylamine)borane (TB) with the D + form of ion-exchange resin suspended in organic solvent was studied. The hydrolysis retardation is observed in two cases: (i) due to inhibition by the hydrolysis side product, trimethylammonium, or (ii) due to resin pretreatment by long-chain cationic surfactants. The effect of hydrolysis inhibition is attributed to adsorption of surfactants on the resin which lowered the concentration of exchangeable deuterons in the reaction zone

Membrane-assisted deuterium-hydrogen exchange reaction on (trimethylamine)borane

The kinetic mechanism of the D-H exchange reaction between (trimethylamine)borane (TMAB) and a cation - exchange membrane in the D + form has been studied. The results obtained indicate that the reaction is first order in TMAB and pseudo first order with increasing D 2 SO 4 concentrations in the membrane. The reaction was shown to be followed by the hydrolysis side reactions of TMAB and its deuteratcd product (TMAB-d 3 ). The hydrolysis resulted in the formation of trimethylammonium, which inhibits the D-H exchange reaction

Trimethylamine–borane bromide as alternative reagent for reductive bromation of aromatic carbonyl compounds

The reaction of bromine with aromatic carbonyl compounds and trimethylamine–borane in chloroform leads to benzyl bromides.

The Molecular Structure of Trimethylamine-Borane as Studied from Gas Electron Diffraction and Spectroscopic Data

Abstract The molecular structure of trimethylamine–borane (CH3)3N·BH3 has been determined from gas electron-diffraction data with spectroscopic data. The molecular parameter values and their uncertainties are rg(B–H)=1.261±0.006 Å, rg(N–B)=1.656±0.002 Å, rg(C–N)=1.485±0.001 Å, rg(C–H)=1.108±0.002 Å, ∠HBH=112.8±0.4°, and ∠CNC=109.2±0.2°. The potential barrier around the N–B bond has been estimated to be larger than 5 kcal mol−1 (1 cal=4.183 J). The isotope effects on the B–D bond distance and the DBD angle have also been estimated to be −0.006 Å and 0.4°, respectively, in rα0 parameters.