Zirconium Borohydride Research Articles

Synthesis of Zirconium Diboride Films and ZrB2/BC x N y Heterostructures

Using mechanochemical synthesis, we have prepared zirconium borohydride, Zr(BH4)4, as a precursor for ZrB2 film growth by chemical vapor deposition. We have carried out the thermodynamic modeling of phase formation processes in the Zr–B–(N)–H and Zr–B–(N)–H–O systems in a wide temperature range, from 100 to 2500°C, at various p(H2)/p(Zr(BH4)4) and p(NH3)/p(Zr(BH4)4) partial pressure ratios in the starting gas mixtures. A process has been proposed for the growth of zirconium diboride films by Zr(BH4)4 decomposition using two techniques: chemical vapor deposition and plasma-enhanced chemical vapor deposition. We also developed a process for the growth of multilayer ZrB2-and BC x N y -based structures.

An initial study of demountable high-temperature superconducting toroidal field magnets for the Vulcan tokamak conceptual design

Recent developments have made it possible to consider high-temperature superconductor (HTS) for the design of tokamak toroidal field (TF) magnet systems, potentially influencing the overall design and maintenance scheme of magnetic fusion energy devices. Initial assessments of the engineering challenges and cryogenic-dependent cost and parameters of a demountable, HTS TF magnet system have been carried out using the Vulcan tokamak conceptual design (R=1.2m, a=0.3m, B0=7T) as a baseline. Jointed at the midplane to allow vertical removal of the primary vacuum vessel and routine maintenance of core components, structural D-shaped steel support cases provide cryogenic cooling for internally routed YBCO superconducting cables. The cables are constructed by layering ∼50μm thick commercially available YBCO tape, and the interlocking steel support cases self align during assembly to form internal resistive joints between YBCO cables. It is found that designing the TF magnet system for operation between 10K and 20K minimizes the total capital and operating cost. Since YBCO is radiation-sensitive, Monte Carlo simulation is used to study advanced shielding materials compatible with the small size of Vulcan. An adequate shield is determined to be 10cm of zirconium borohydride, which reduces the nuclear heating of the TF coils by a factor of 11.5 and increases the YBCO tape lifetime from two calendar years in the unshielded case to 42 calendar years in the shielded case. Although this initial study presents a plausible conceptual design, future engineering work will be required to develop realistic design solutions for the TF joints, support structure, and cryogenic system.

ChemInform Abstract: Reaction of Zirconium Borohydride with Aluminum Hydride in Ether.

ChemInform Abstract: Reaction of Zirconium Borohydride with Aluminum Hydride in Ether.

Advanced neutron shielding material using zirconium borohydride and zirconium hydride

Neutron transport calculations have been carried out to assess the capability of zirconium borohydride (Zr(BH 4) 4) and zirconium hydride (ZrH 2) as advanced shield materials, because excellent shields can be used to protect outer structural materials from serious activation. The neutron shielding capability of Zr(BH 4) 4 is lower than ZrH 2, even though the hydrogen density of Zr(BH 4) 4 is slightly higher than that of ZrH 2. High-Z atoms are effective in neutron shielding as well as hydrogen atoms. The combination of steel and Zr(BH 4) 4 can improve the neutron shielding capability. The combinations of (Zr(BH 4) 4 + F82H) and (ZrH 2 + F82H) can reduce the thickness of the shield by 6.5% and 19% compared to (water + F82H), respectively. The neutron flux for Zr(BH 4) 4 is drastically reduced in the range of neutron energy below 100 eV compared to other materials, due to the effect of boron, which can lead to a reduction of radwaste from fusion reactors.

A Novel One‐Pot Reductive Amination of Aldehydes and Ketones with Lithium Perchlorate and Zirconium Borohydride—Piperazine Complexes.

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A novel one-pot reductive amination of aldehydes and ketones with lithium perchlorate and zirconium borohydride–piperazine complexes

A novel, one-pot reductive mono-alkylation method of amines (primary and secondary), 1,2-phenylenediamine, O-trimethylsilylhydroxylamine, and N, N-dimethylhydrazine was developed using LiClO 4 (5 mol %) as a source for in situ generation of imine, iminium ion, oxime, and hydrazone, and zirconium borohydride–piperazine complex as reducing agent. This condition is especially useful for situations in which it is not practical to use the amine in excess (as is typically the case under acid-catalyzed conditions) or for acid-sensitive compounds.

Zirconium Borohydride Piperazine Complex: An Efficient, Air and Thermally Stable Reducing Agent.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Zirconium borohydride piperazine complex, an efficient, air and thermally stable reducing agent

A zirconium borohydride piperazine complex (Ppyz)Zr(BH 4) 2Cl 2, obtained by the reaction of an ethereal solution of ZrCl 4 and LiBH 4 with piperazine is a stable, selective and efficient reducing agent. (Ppyz)Zr(BH 4) 2Cl 2 reduces aldehydes, ketones, silylethers, α,β-unsaturated carbonyl compounds and esters. The reactions were performed in diethyl ether at room temperature or under reflux, and the yields of the corresponding alcohols were excellent. The selective reduction of aldehydes in the presence of ketones and complete regioselectivity in the reduction of α,β-unsaturated carbonyl groups were observed.

Dichlorobis[1,4‐diazabicyclo(2,2,2)octane](tetrahydroborato)zirconium, [Zr(BH4)2Cl2(dabco)2] (ZrBDc), a New Stable, Efficient, and Selective Reducing Agent.

AbstractFor Abstract see ChemInform Abstract in Full Text.

DICHLOROBIS[1,4-DIAZABICYCLO(2,2,2)OCTANE]-(TETRAHYDROBORATO)ZIRCONIUM, [Zr(BH4)2CL2(dabco)2] (ZrBDC), A NEW STABLE, EFFICIENT, AND SELECTIVE REDUCING AGENT

ABSTRACT High yield preparation of a new stable zirconium borohydride, [Zr(BH4)2Cl2(dabco)2] is described and its application for the selective and efficient reduction of aldehydes and ketones is presented.

Zirconium Borohydride - a Versatile Reducing Agent for the Reduction of Electrophilic and Nucleophilic Substrates

Zirconium borohydride, a potential reducing agent, reduces acids, esters, imines to the corresponding alcohols and secondary amines in good yield at room temperature within two hours. This facile reducing property was taken advantage off in the synthesis of pheromones and some novel chiral precursors for asymmetric synthesis.

Disproportionation of Cationic Zirconium Complexes: A Possible Pathway to the Deactivation of Catalytic Cationic Systems

Protonolysis of the zirconium borohydride [(C5H4R)2Zr(BH4)2] (R = H, Me, SiMe3) with NHMe2PhBPh4 in THF leads to the corresponding cationic zirconium complex [(C5H4R)2Zr(BH4)(THF)]BPh4, and the structure of [(C5H4Me)2Zr(BH4)(THF)]BPh4 was determined. In the presence of phosphine, PMe2Ph, the formation of the cationic hydride [(C5H4R)2ZrH(PMe2Ph)2]BPh4 is observed by 1H and 31P NMR followed by a disproportionation and a redox reaction with [BPh4]-, giving the neutral [(C5H4R)2ZrH(μ-H)]2 and the cationic ZrIII species [(C5H4R)2Zr(PMe2Ph)2]BPh4 characterized by EPR spectroscopy and suggesting a probable pathway in the deactivation of cationic catalyst systems.

Novel Zirconium Borohydride Complexes: Syntheses and Molecular Structures of [Zr(.eta.-C8H6(SiMe3)2)(.eta.3-BH4)(.eta.2-BH4)] and [(.eta.-C8H6(SiMe3)2)Zr(.mu.-.eta.6:.eta.4-C8H6(SiMe3)2)(.mu.-H)Zr(.eta.3-BH4)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNovel Zirconium Borohydride Complexes: Syntheses and Molecular Structures of [Zr(.eta.-C8H6(SiMe3)2)(.eta.3-BH4)(.eta.2-BH4)] and [(.eta.-C8H6(SiMe3)2)Zr(.mu.-.eta.6:.eta.4-C8H6(SiMe3)2)(.mu.-H)Zr(.eta.3-BH4)]Stephen C. P. Joseph, F. Geoffrey N. Cloke, Christine J. Cardin, and Peter B. HitchcockCite this: Organometallics 1995, 14, 7, 3566–3569Publication Date (Print):July 1, 1995Publication History Published online1 May 2002Published inissue 1 July 1995https://doi.org/10.1021/om00007a066RIGHTS & PERMISSIONSArticle Views126Altmetric-Citations16LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-AlertsSupporting Info (2)»Supporting Information Supporting Information Get e-Alerts

Polymer supported ziroconium borohydride: a stable, efficient and regenerable reducing agent

The unstable zirconium borohydride, Zr(BH4)4, is stabilized on polyvinylpyridine andused as a new, stable, efficient and regenerable polymer supported transition-metal borohydride reagent for reduction of a variety of carbonyl compounds.

Zirconium Borohydride as a Zirconium Boride Precursor

Synthesis of zirconium boride, ZrB2, from zirconium borohydride, Zr(BH4)4, has been explored by a variety of methods, including chemical vapor deposition (CVD) in a hot tube, laser CVD with both continuous‐wave (cw) and pulsed lasers, and cw‐laser synthesis of fine powders. In all cases, ZrB2 was the only crystalline product identified. Products made at high temperature contained excess boron, while those made at low temperature were boron‐deficient.

ChemInform Abstract: Reaction of Zirconium Borohydride (I) with Aluminum Hydride (II) in Diethyl Ether.

AbstractThe formation of Zr(AlH4)3BH4·2 Et2O is observed when (I) and (II) are allowed to react in a 1:5.3 molar ratio.

Effect of additives on the oxidation of zirconium borohydride

Effect of additives on the oxidation of zirconium borohydride

Inelastic neutron scattering from zirconium borohydride

The inelastic neutron scattering spectra, in both energy gain and energy loss, were obtained for zirconium borohydride. Bands were assigned to optically active and inactive modes, and the barrier to reorientation about the metal to boron axis calculated. Significant coupling between the borohydride rotors was observed. Two of the optically inactive fundamentals v5(A2) and v15(F1) were identified from the neutron spectrum.

The nature of uranium borohydride in its vapour and solid phases from infrared spectra

A preliminary X-ray diffraction study of uranium borohydride, U(BH,),, has recently been reported’. It was concluded that the compound is polymeric in the solid with six BH4 groups associated with each uranium atom. Four of these are involved in U-(BH4)-U bridges and the rest are terminal [U-(BH,) type]. The authors deferred an assessment of the nature of the hydrogen bridging present until neutron diffraction studies were completed, but noted that the X-ray data were not inconsistent with double hydrogen bridges between all bonded uranium and boron atoms. An X-ray structure determination’ of solid (160 “C) zirconium borohydride, Zr(BH ) 4 4r and an electron diffraction study of Zr(BHq)q vapou? were both interpreted in terms of a monomeric structure in which tetrahedrally arranged boron atoms arc bonded through triple hydrogen bridges to the central metal atom. A recent vibrational study of zirconium borohydride and hafnium borohydride in the gas phase and in solution has strongly implied a triple bridge structure of Td molecular symmetry *. We wish to report the infrared spectrum of vapour phase uranium borohydride and compare it with the solid phase spectrum.

Study of the zirconium borohydride molecule by electron diffraction by gases

Study of the zirconium borohydride molecule by electron diffraction by gases