Reaction Of NaBH4 Research Articles

Mechanisms involved in chemical vapor generation by aqueous tetrahydroborate(III) derivatization: Role of hexacyanoferrate(III) in plumbane generation

The role played by K 3Fe(CN) 6 (0.08 or 1.5 g l − 1 ) in producing strong enhancement factors in the generation efficiency of plumbane in the reaction of NaBH 4 (10 or 40 g l − 1 ) with Pb(II) (50 μg l − 1 ) in 0.1 M HCl solution, was investigated by using continuous flow chemical vapor generation coupled with atomic fluorescence spectrometry (CF-CVG-AFS). Different mixing sequences and reaction times of reagents were tested using different chemifold setups. Part of CF-CVG-AFS experiments were performed using the on-line, delayed addition of Pb(II) to a K 3Fe(CN) 6 + NaBH 4 reaction mixture. Kinetic calculations estimating the concentration of K 3Fe(CN) 6 remaining in the K 3Fe(CN) 6 + NaBH 4 reaction mixture before it merged with Pb(II) solution were also performed. Batch experiments measuring the amount of hydrogen evolved (pressure of H 2 vs time) and pH variation during K 3Fe(CN) 6 + NaBH 4 + HCl reaction were performed in order to have a correct estimation of the concentration of K 3Fe(CN) 6 remaining in the reaction system. The comparison of CF-CVG-AFS experiments with kinetic calculations indicates that strong enhancement factors of plumbane generation can be obtained without any interaction of K 3Fe(CN) 6 with Pb(II). The key role of K 3Fe(CN) 6 is recognized in its reaction with NaBH 4 to give “special” borane complex intermediates, which are highly effective in the generation of plumbane from Pb(II).

Characterization of a multimode sample introduction system (MSIS) for multielement analysis of trace elements in high alloy steels and nickel alloys using axially viewed hydride generation ICP-AES

A commercial multimode sample introduction system (MSIS) was characterized for simultaneous multielement hydride and nonhydride-forming elements (As, Bi, Co, Cr, Fe, Mn, Mo, Ni, Sb, Se, Sn, Ti, V, W) in high alloy steels and nickel alloys by axially viewed ICP-AES. Vapor formed by the NaBH4 reaction and aerosol from a specially designed dual conical spray chamber and pneumatic nebulizer were injected simultaneously into a robust plasma. Spectroscopic effects caused by major and minor elements and nonspectroscopic interferences induced by matrix concomitants were evaluated both for conventional nebulization and for hydride generation. The objective of the study was to establish optimized operating conditions whereby both nonhydride and hydride forming elements could be determined simultaneously. It was observed that the sensitivities of the ‘hydride generating’ elements using a MSIS, were similar to those observed using conventional hydride generation. In comparison to conventional pneumatic nebulization, hydride LODs, were enhanced significantly by factors varying from about 2–20. Limits of detection using the MSIS, for nonhydride elements (Co, Cr, Fe, Mn, Mo, Ni, Ti, V, W) were similar to those reported for the conventional sample introduction system. Several fundamental parameters such as Mg II 280.270/Mg I 285.213 nm ratios, excitation temperature (Tex) and the effect of hydrogen were also determined. The effect of hydrogen, formed during hydride generation, on intensities of nonhydride and hydride forming elements and excitation temperature was evaluated. This is important because hydrogen can modify the properties of the ICP. The effect of variable concentrations of tartaric acid, L-cystein, EDTA, and 1,1,3,3-tetramethy-2-thiourea as retarding agents for reducing deleterious effects of Ni was investigated. The accuracy of the procedure was verified by analyzing several certified reference metallurgical samples. An important conclusion of this multielement study is that the application of the MSIS for simultaneous determination of hydride forming and non-hydride forming elements in complex metallurgical samples by ICP-AES is constrained by matrix derived spectral line interferences.

Synthesis and structural characterization of new mixed-ring indenyl derivatives of molybdenum containing phosphorus ligands

Reaction of NaBH 4 with [IndCpMo(dppe)](BF 4) 2 ( 1) in acetone yields [IndMo(η 4-C 5H 6)(dppe)]BF 4 ( 2) quantitatively. The hydride addition takes place at the external face of the Cp ring. Dissolution of 2 in dichloromethane gives [IndMo(η 4-C 5H 5- exo-CH 2Cl)(dppe)]BF 4, as confirmed by elemental analysis, IR and 1H NMR spectroscopy. The similar dication [IndCpMo{P(OMe) 3} 2](BF 4) 2 ( 4) reacts with NaBH 4, in a solvent dependent manner. In acetonitrile, [IndMo(η 4-C 5H 6){P(OMe) 3} 2]BF 4 ( 5) is obtained and in acetone a P(OMe) 3 ligand is lost resulting in the asymmetric phosphite-hydride, [IndCpMoH{P(OMe) 3}] + ( 6). The molecular structures of [IndMo(η 4-C 5H 6){P(OMe) 3} 2]PF 6 and [IndCpMoH{P(OMe) 3}]PF 6 were characterized by single-crystal X-ray diffraction.

Synthesis and metal-ion binding properties of new N2S4- and N2S5-donor macrocycles

Synthetic procedures for new N2S4- and N2S5-donor macrocycles (2 and 4) were given. The ligands were prepared by the reaction of NaBH4 with the appropriate macrocyclic diamide in the presence of boron trifluoride ethyl etherate in dry tetrahydrofuran (THF). Solvent extraction method was used to evaluate metal-ion binding properties of the new ligands. The solvent extraction experiments suggested that the reduced macrocycles have Ag+ and Hg2+ selectivities compared to Pb2+, Co2+, Zn2+, Ni2+, Cu2+, Mn2+ and Cd2+ ions. The extraction constants (log K ex) and complex compositions were determined for Ag+ and Hg2+ complex of compound (4).

Very Small and Soft Scorpionates: Water Stable Technetium Tricarbonyl Complexes Combining a Bis-agostic (k3-H, H, S) Binding Motif with Pendant and Integrated Bioactive Molecules

The novel trihydro(mercaptoazolyl)borates Na[H(3)B(tim(Me))] (L(1)) (tim(Me) = 2-mercapto-1-methylimidazolyl), Na[H(3)B(tim(Bupip))] (L(2)) (tim(Bupip) = 1-[4-((2-methoxyphenyl)-1-piperazinyl)butyl]-2-mercaptoimidazolyl), and Na[H(3)B(bzt)] (L(3)) (bzt = 2-mercaptobenzothiazolyl) were synthesized by reaction of NaBH(4) with the corresponding azole. Ligands L(1)-L(3) represent a new class of light and soft scorpionates that stabilizes the [M(CO)(3)](+) core (M = (99)Tc, Re) by formation of the complexes fac-[M{kappa(3)-H(mu-H)(2)B(tim(Me))}(CO)(3)] (M = (99)Tc (1), Re (2)), fac-[Re{kappa(3)-H(mu-H)(2)B(tim(Bupip))}(CO)(3)] (3), and fac-[Re{kappa(3)-H(mu-H)(2)B(bzt)}(CO)(3)] (4), respectively. The soft scorpionates are coordinated to the metal in unique (kappa(3)-H, H', S) fashion, as confirmed by X-ray crystallography of 1, 2, and 4. These complexes with bis-agostic hydride coordination are formed in aqueous solution with the two hydrides replacing two coordinating aquo ligands. The agostic hydrogen atoms were located directly, confirming an unprecedented donor atom set combining one sulfur and two hydrogen atoms. Preliminary studies have shown the possibility of preparing some of these complexes at the no carrier added level ((99m)Tc), under conditions as required in radiopharmaceutical preparation. Due to their lipophilicity, small-size, and easy functionalization with adequate biomolecules, the trihydro(mercaptoazolyl)borate technetium tricarbonyl complexes are suitable for the design of CNS receptor ligand radiopharmaceuticals as exemplified with 3, comprising a pendant serotonergic 5-HT(1A) ligand. The integrated design of radiopharmaceuticals involving a bis-agostic scorpionate ligand is demonstrated by the synthesis of 4, with an integrated benzothiazolyl fragment for the recognition of beta-amyloid plaques.

One simple synthesis route to whisker-like nanocrystalline boron nitride by the reaction of NaBH 4 and NaN 3

Nanocrystalline boron nitride (BN) was synthesized via a simple route by the reaction of sodium borohydride with sodium azide in an autoclave at 600 °C. X-ray powder diffraction pattern indicated that the product was hexagonal BN, and the cell constant was a = 2.495 Å, c = 6.687 Å. Transmission electron microscopy image showed that it consisted of whisker-like particles with an average size of 200 nm × 20 nm. The product was also studied by FT-IR, XPS and TGA. It has good thermal stability and oxidation resistance in high temperature.

New Insights on the Mechanism of Palladium-Catalyzed Hydrolysis of Sodium Borohydride from 11B NMR Measurements

To gain insight on the mechanistic aspects of the palladium-catalyzed hydrolysis of NaBH(4) in alkaline media, the kinetics of the reaction has been investigated by (11)B NMR (nuclear magnetic resonance) measurements taken at different times during the reaction course. Working with BH(4)(-) concentration in the range 0.05-0.1 M and with a [substrate]/[catalyst] molar ratio of 0.03-0.11, hydrolysis has been found to follow a first-order kinetic dependence from concentration of both the substrate and the catalyst (Pd/C 10 wt %). We followed the reaction of NaBH(4) and its perdeuterated analogue NaBD(4) in H(2)O, in D(2)O and H(2)O/D(2)O mixtures. When the process was carried out in D(2)O, deuterium incorporation in BH(4)(-) afforded BH(4)(-)(n)D(n)(-) (n = 1, 2, 3, 4) species, and a competition between hydrolysis and hydrogen/deuterium exchange processes was observed. By fitting the kinetics NMR data by nonlinear least-squares regression techniques, the rate constants of the elementary steps involved in the palladium-catalyzed borohydride hydrolysis have been evaluated. Such a regression analysis was performed on a reaction scheme wherein the starting reactant BH(4)(-) is allowed both to reversibly exchange hydrogen with deuterium atoms of D(2)O and to irreversibly hydrolyze into borohydroxy species B(OD)(4)(-). In contrast to acid-catalyzed hydrolysis of sodium borohydride, our results indicate that in the palladium-catalyzed process the rate constants of the exchange processes are higher than those of the corresponding hydrolysis reactions.

Dual mode sample introduction for multi-element determination by ICP-MS: the optimization and use of a method based on simultaneous introduction of vapor formed by NaBH4 reaction and aerosol from the nebulizer

A method has been developed utilizing dual mode sample introduction of a commercial Multi Mode Sample Introduction System (MSIS™) for simultaneous multi-element (As, Bi, Cd, Co, Cu, Ni, Pb, Sb, Zn) determination by ICP-MS. Vapor formed by NaBH4 reaction and aerosol from the nebulizer were introduced simultaneously into the plasma. The effects of parameters that are expected to affect hydride generation of As, Bi and Sb, i.e. concentrations of HNO3, NaBH4 and thiourea, plus flow rates of sample and NaBH4, were evaluated using Plankett–Burman experimental design. Then, the most significant of the parameters were optimized using a central composite design. Further, as optimum values were not the same for all the elements, a response optimizer was used to obtain a compromised optimum. Except for Pb, the sensitivity of the ‘classical’ hydride generating elements (As, Bi and Sb) increased significantly using the dual mode sample introduction, compared to pneumatic nebulization. The factors of sensitivity increase for As, Bi and Sb were 77, 33 and 56, respectively. For the other elements (Cd, Co, Cu, Ni and Zn), that are also reported to react with NaBH4 forming volatile species, no significant change in sensitivity was observed. The limits of detection obtained for As, Bi, and Sb using dual mode sample introduction were 7, 15 and 10 pg mL−1, respectively. The use of thiourea as a pre-reducing agent and masking agent was also investigated. The accuracy of the method was verified by analyzing various certified reference materials (CRMs): SRM1572 ‘Citrus leaves’, SRM1575 ‘Pine Needles’, SRM1643e ‘Trace Elements in Water’, GBW07602 ‘Bush Branches and Leaves’ and GBW07601 ‘Human hair’.

Syntheses and characterizations of Co(II) and Ni(II) complexes of dihydrobis(thioxotetrazolyl)borato with Co[S 4] and Ni[S 4H 2] cores

The sodium salt of the dihydrobis(1-methyl-5-thiotetrazolyl)borato anion [Btt Me] − has been synthesized by the reaction of NaBH 4 with 1-methyl-5-thiotetrazole. Treatment of Na[Btt Me] with anhydrous CoCl 2 and NiCl 2 · 6H 2O, respectively, gives the complexes Co(Btt Me) 2 ( 1) and Ni(Btt Me) 2 ( 2), which have been characterized by IR, 1H NMR, ESI-MS, UV–Vis spectroscopy as well as X-ray crystallography. Compound 1 contains a central [CoS 4] core and exhibits a slightly distorted trigonal-bipyramidal coordination geometry with a very weak apical Co⋯H–B interaction, whereas 2 features a central [NiS 4H 2] core in a distorted octahedral coordination geometry and exhibits relatively strong Ni⋯H–B interactions. These results indicate that the ligand can act in the bidentate ( k 2-S,S) or tridentate ( k 3-S,S,BH) mode. The electrochemical behavior of 1 and 2 has also been investigated by cyclic voltammetry.

Ruthenium dioxide nanoparticles in ionic liquids: synthesis, characterization and catalytic properties in hydrogenation of olefins and arenes

The reaction of NaBH4 with RuCl3 dissolved in 1-n-butyl-3-methylimidazolium hexafluorophosphate (BMI.PF6) ionic liquid is a simple and reproducible method for the synthesis of stable RuO2 nanoparticles with a narrow size distribution within 2-3 nm. RuO2 nanoparticles were characterized by XRD, XPS, EDS and TEM. These nanoparticles showed high catalytic activity either in the solventless or liquid-liquid biphasic hydrogenation of olefins and arenes under mild reaction conditions. Hg(0) and CS2 poisoning experiments and XRD and TEM analysis of particles isolated after catalysis indicated the formation of Ru(0) nanoparticles. The nanoparticles could be re-used in solventless conditions up to 10 times in the hydrogenation of 1-hexene yielding a total turnover number for exposed Ru atoms of 175,000.

Application of thermal analytical techniques in development of a safe and robust process for production of triacetoxyborohydride (STAB)

The thermal hazards associated with the original procedure to produce sodium triacetoxyborohydride (STAB) from the reaction of NaBH 4 with glacial acetic acid were identified using various thermal analytical techniques. A substantial amount of NaBH 4 reagent accumulated at the end of the addition. As a result, a large heat spike occurred in the subsequent temperature ramp, which had the potential to initiate STAB decomposition and to generate a significant amount of non-condensable gases. Moreover, this rapid heat release was also accompanied by a rapid and uncontrollable generation of hydrogen gas from consumption of the accumulated NaBH 4. Evaluation of the reaction kinetics provided the fundamental information needed to develop a safe and robust process. The current procedure, utilizing a solution of NaBH 4 in DMAC, provides sufficient control of the heat and hydrogen gas release rates to reduce the processing hazard and eliminate the requirement for specially rated equipment for charging the NaBH 4 solids to the reactor.

Reaction of BH4−with {Mo2Cp2(μ-SMe)n} species to give tetrahydroborato, hydrido or dimetallaborane compounds: control of product by ancillary ligands

The reaction of mono- or dichloro-dimolybdenum(III) complexes [Mo2Cp2(mu-SMe)2(mu-Cl)(mu-Y)] (Cp=eta5-C5H5; 1, Y=SMe; 2, Y=PPh2; 3, Y=Cl) with NaBH4 at room temperature gave in high yields tetrahydroborato (8), hydrido (9) or metallaborane (12) complexes depending on the ancillary ligands. The correct formulation of derivatives and has been unambigously determined by X-ray diffraction methods. That of the hydrido compound 9 has been established in solution by NMR analysis and confirmed by an X-ray study of the mu-azavinylidene derivative [Mo2Cp2(mu-SMe)2(mu-PPh2)(mu-N=CHMe)] (10) obtained from the insertion of acetonitrile into the Mo-H bond of 9. Reaction of NaBH4 with nitrile derivatives, [Mo2Cp2(mu-SMe)4-n(CH3CN)2n]n+(5, n=1; 6 n=2), afforded the tetrahydroborato compound 8, together with a mu-azavinylidene species [Mo2Cp2(mu-SMe)3(mu-N=CHMe)](14), when n=1, and the metallaborane complex 12, together with a mixed borohydrato-azavinylidene derivative [Mo2Cp2(mu-SMe)2(mu-BH4)(mu-N=CHMe)] (13), when n=2. The molecular structures of these complexes have been confirmed by X-ray analysis. Preparations of some of the starting complexes (3 and 4) are also described, as are the molecular structures of the precursors [Mo2Cp2(mu-SMe)2(mu-X)(mu-Y)] (1, X/Y=Cl/SMe; 2, X/Y=Cl/PPh2; 4, X/Y=SMe/PPh2).

Chemical modification of chitosan: Synthesis and characterization of chitosan‐crown ethers

AbstractFour novel Schiff‐type chitosan (CTS)‐crown ethers were synthesized through a reaction between NH2 in CTS or crosslinked chitosan (CCTS) and CHO in 4′‐formylbenzo‐crown ethers, and four secondary‐amino‐type CTS‐crown ethers were prepared through the reduced reaction of NaBH4, respectively. Their structures were characterized by elemental analysis, Fourier transform infrared (FTIR) spectra analysis, solid‐state 13C‐NMR analysis, and X‐ray diffraction (XRD) analysis. The elemental analysis results showed that the percentage of nitrogen in all CTS‐crown ethers were lower than that of CTS or CCTS. From the FTIR data of CTS, CCTS, and CTS‐crown ethers I–VIII, we saw that the characteristic peaks of CN, NH, and Ar appeared and that the characteristic peaks of pyranoside in the chain of CTS or CCTS were not destroyed. The XRD spectra demonstrated that CTS‐crown ethers I–VIII gave lower crystallinities than CTS or CCTS, which indicated that these compounds were considerably more amorphous than CTS or CCTS. In the solid‐state 13C‐NMR spectra, all of these CTS‐crown ethers had a particular peak of aromatic at 128 or 129 ppm, and the greatest difference between Schiff‐type CTS‐crown ethers and secondary‐amino‐type CTS‐crown ethers was that the Schiff‐type CTS‐crown ethers had the particular peak of CN, which disappeared in secondary‐type CTS‐crown ethers. All these facts confirmed that the structures of CTS‐crown ethers I–VIII were as expected. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2221–2225, 2003

Ruthenium hydrides bearing SbPh 3 and AsPh 3 ligands: characterization of the bis(dihydrogen) complexes [Cp*Ru(H 2) 2(EPh 3)] + (Cp*=C 5Me 5; E=Sb, As)

Reaction of NaBH 4 with [Cp*RuCl 2(EPh 3)] (E=Sb 1a, As 1b) in THF/EtOH affords the trihydride complexes [Cp*RuH 3(EPh 3)] (E=Sb 2a, As 2b) in good yield. These trihydrides are protonated by HBF 4·OEt 2 in CH 2Cl 2 at −80 °C furnishing the cationic bis(dihydrogen) complexes [Cp*Ru(H 2) 2(EPh 3)][BF 4] (E=Sb 3a, As 3b), which were characterized in solution by T 1 and 1 J HD measurements. These species are unstable and decompose at T>0 °C. The reaction of [Cp*RuCl(SbPh 3) 2] with H 2 and NaBAr′ 4 in fluorobenzene yields the dihydride [Cp*RuH 2(SbPh 3) 2][BAr′ 4] ( 5). Protonation of the monohydride [Cp*RuH(SbPh 3) 2] ( 6) by HBF 4·OEt 2 in CH 2Cl 2 at −80 °C generates the dihydrogen complex [Cp*Ru(H 2)(SbPh 3) 2] + ( 7), which rearranges to its dihydride tautomer 5 when the temperature is raised.

Photoreduction of bacteriorhodopsin Schiff base at low humidity. A study with C13=C14 nonisomerizable artificial pigments.

The retinal protonated Schiff base of bacteriorhodopsin is photoreactive to reducing agents such as NaBH4. In the present work we have studied the effect of different protein hydration levels on the photoreductive reaction, as well as the consequences of preventing isomerization around the critical C13=C14 retinal double bond. It was revealed that the rate of light-induced NaBH4 reaction can be fitted to three phases, between 100 and 87%, from 87 to 35% and below 35% relative humidities (r.h.). The three phases are attributed to three protein regions characterized by different water affinities. Furthermore, it is shown that the PSB reduction reaction is light catalyzed even in artificial pigments derived from retinal analogs, in which isomerization around the C13=C14 double bond is prevented. It is suggested that the protein experiences light-induced conformational alterations that are not associated with C13=C14 double bond isomerization. In the 13-cis locked pigment the rate of reduction reaction is affected by r.h. levels only below 35%. The relatively low r.h. required for withdrawing water from the protein is attributed to the increased protein-water affinity in this specific pigment.

Reactions of sodium tetrahydridoborate with tris(pyrazolyl)methane ligands. Syntheses and solid state structures of {[HC(pz) 3](thf)Na(μ 1 1 ,μ 1 1 -BH 4)} 2 and {[HC(3,5-Me 2pz) 3] 2Na}(BH 4) (pz=pyrazolyl ring, thf=tetrahydrofuran)

The reaction of NaBH 4 and HC(pz) 3 in thf yields {[HC(pz) 3](thf)Na(μ 1 1 ,μ 1 1 -BH 4)} 2. The solid state structure shows that the two BH 4 ligands bridge the sodium atoms in an unusual manner such that only one hydrogen in each bonds to each sodium forming two μ 1 1 ,μ 1 1 -type bonds. The reaction of HC(3,5-Me 2pz) 3 and NaBH 4 in either a 1:1 or 2:1 ratio yields {[HC(3,5-Me 2pz) 3] 2Na}(BH 4). The solid state structure shows that both HC(3,5-Me 2pz) 3 ligands are coordinated to sodium in a trigonally distorted octahedral arrangement and the BH 4 group is the counter-ion.

Oxidative Addition to Diplatinum(II) Complexes: Stereoselectivity and Cooperative Effects

The stereochemistry of oxidative addition of MeI and MeO3SCF3 to binuclear dimethylplatinum(II) complexes containing bis(bidentate) ligands such as cis- and trans-1,2-C6H10(NCH-2-C5H4N)2, 1 and 2a, has been studied. Oxidative addition of the Me−X bond (X = I or CF3SO3) occurred at both dimethylplatinum centers, often with high stereoselectivity, to give bis(trimethylplatinum(IV)) complexes. Two types of adducts were formed, either neutral complexes containing {PtMe3X}2 groups or ionic complexes containing [(PtMe3)2(μ-X)]+X- groups. When X = iodide, both forms were detected, but when X = triflate, the ionic form with one bridging triflate ligand dominated. The triflate ligand was easily displaced by water to give an aqua complex, and reaction of NaBH4 with cis-1,2-[C6H10{NCH-2-C5H4N(PtMe3)}2(μ-O3SCF3)][O3SCF3] gave the platinum(IV) borohydride complex cis-1,2-[C6H10{NCH-2-C5H4N(PtMe3)}2(μ-BH4)][O3SCF3] as a single diastereomer. Addition of PPh3 to trans-1,2-[C6H10{NCH-2-C5H4N(PtMe3)}2(μ-O3SCF3)][O3SCF3] gave C2-symmetric trans-1,2-[C6H10{NCH-2-C5H4N(PtMe3PPh3)}2][O3SCF3]2, with a change in absolute configuration.

Improved procedures for the generation of diborane from sodium borohydride and boron trifluoride.

Improved procedures for the generation of diborane by the reaction of NaBH4 in triglyme or tetraglyme with the BF3 adducts of di-n-butyl ether, tert-butyl methyl ether, monoglyme, dioxane, and tetrahydropyran were developed. In these systems, generation of diborane requires 2-4 h at 25 degrees C (faster reactions take place at 50 degrees C). The byproduct NaBF4 precipitates from the reaction mixture at 25 degrees C as the reaction proceeds. The high-boiling glyme can be conveniently separated from the lower boiling carrier ethers by simple distillation of the latter. On the other hand, diborane was generated very slowly or not generated using the addition of each of six boron trifluoride-etherates (di-n-butyl ether, tert-butyl methyl ether, tetrahydrofuran, tetrahydropyran, dioxane, and monoglyme) to suspensions of sodium borohydride in the corresponding ether. However, diborane was generated rapidly and quantitatively by the addition of NaBH4 in triglyme (or tetraglyme) to the BF3 adduct of triglyme (or tetraglyme) at room temperature. No solid precipitation occurs during the reaction, making it convenient for large-scale applications. The pure solvent triglyme (or tetraglyme) can be easily recovered and recycled by either crystallizing or precipitating NaBF4 from the generation flask. New procedures for the generation of diborane were also developed by the reaction of NaBF4 with NaBH4 in triglyme (or tetraglyme) in the presence of Lewis acids such as AlCl3 and BCl3.

Hydride transfer reactions in dimolybdenum compounds: a simple route to the novel μ-η1∶η1-tetrahydroboride complex [Mo2Cp2(μ-SMe)3(μ-BH4)

The reaction of NaBH4 with the bis-nitrile compound [Mo2Cp2(μ-SMe)3(MeCN)2](BF 4) 1 unexpectedly gives rise to the rare, stable μ-(η1-H):(η1-H) tetrahydroborato complex [Mo2Cp2(μ-SMe)3(μ-BH4)] 2, in addition to the expected azavinylidene product [Mo2Cp2(μ-SMe)3(μ-η1 -NCHMe)] 3.

Synthesis and characterization of poly(aminoborane) as a new boron nitride precursor

During the solution reaction of NaBH4/(NH4)2SO4 in tetraglyme to form borazine, polymeric aminoborane (NH2BH2)x has been isolated as a white powder. The powder was characterized by thermal gravimetric analysis/differential scanning calorimetry, infrared and mass spectroscopies, and powder X-ray diffraction. Solid-state 15N and 11B nuclear magnetic resonance firmly proved that the chain-like poly(aminoborane) evolved a partially condensed B3N3 ring structure by dehydrogenative condensation between chains at 200 °C. Pyrolysis of the polymer in a nitrogen stream up to 1400 °C led to a 75% yield of hexagonal boron nitride with an interlayer spacing of 3.37 Å. Copyright © 1999 John Wiley & Sons, Ltd.