电感耦合等离子体质谱法测定碳化硼中的硼同位素丰度

以碳酸钙为熔剂高温分解,硝酸浸取、硫酸沉淀的方法处理碳化硼样品,稀释后直接进行多接收电感耦合等离子体质谱分析,对碳化硼中的硼同位素丰度进行测定。扫描电镜分析结果表明,碳化硼颗粒形状不规则,尺寸小于50μm。利用建立的方法处理样品,可实现碳化硼样品的完全溶解,回收率接近100%。对样品中10B丰度进行分析,相对标准偏差为0.023%~0.035%(n=6),测量结果与参考值在不确定度范围内保持一致,证明实验方法可行。所建立的碳化硼样品测量方法样品处理步骤简便,分析速度快,测量精度高,可作为碳化硼中硼同位素丰度的常规分析方法。     

Boron−Boron Dehydrocoupling of Boranes Initiated by Reaction with Iodine

A new boron–boron dehydrocoupling strategy was established, providing convenient access to some diborane(4) compounds starting from simple borane adducts under mild conditions. In contrast to the traditional pathway using a reducing reagent, the reduction from B^III to B^II was paradoxically initiated by the addition of the oxidation-reagent iodine. A reaction pathway for this unusual reaction was proposed based on quantum-chemical calculations.     

硼团簇、硼烷及金属硼化物的研究现状

硼原子因其半径小、缺电子、配位数大、价电子sp²杂化和三中心键等特点引起了科学家的高度关注。其团簇的电子结构、稳定性、芳香性和成键方式等性质的研究成为化学领域的一大热点。由于硼化物多样性的特点,其在光学、能源和储存工业气体方面具有潜在的应用价值。本文简述了近几年全硼团簇、硼烷及金属硼化物的研究现状。其中,分别从中性、阴离子和阳离子三种形式对全硼团簇和硼烷进行概括;金属掺杂硼化物主要包括金属掺杂的纯硼团簇和硼烷、过渡金属掺杂的三明治形式复合物以及金属中心硼分子轮。     

Boron nanotubes.

A survey of novel classes of nanotubular materials based on boron is presented. Pure boron nanotubes are a consequence of a general Aufbau principle for boron clusters and solid boron phases, which postulates various novel boron materials besides the well-known bulk phases of boron based on boron icosahedra. Furthermore, several numerical studies suggest the existence of a large family of compound nanotubular materials derived from crystalline AlB2. We compare these novel boron-based nanotubular materials to standard nanotubular systems built from carbon, and point out a number of remarkable structural and electronic properties that make boron-based nanotubular materials an ideal component for composite nanodevices and extended nanotubular networks.     

ICP-AES法测定硼镁肥中枸椽酸溶硼

微量枸椽酸溶硼测定是肥料检测中的常见项目,用以评估硼肥肥效。其测定方法大多复杂繁琐,操作条件苛刻。如用姜黄素或其他显色剂的分光光度法,体系中因有柠檬酸存在,产生的影响难以处理,测定结果重现性差,限制了测硼的快速和准确性。ICP-AES法较其它方法相比是一种精密度高、重现性好的方法[1],各元素对硼干扰较少,20 g·L-1柠檬酸在炬管处不会炭化引起阻塞,对硼的干扰也可得到校正,使得ICP-AES法测定稀柠檬酸有机溶液中硼成为可能。该方法操作简便、快速,检出限可达0.003 5%,回收率为86%,适用于硼镁肥中微量枸椽酸溶硼测定。枸椽酸溶…     

Polymer-Supported Boron Trifluoride

Polystyrene, cross-linked with 7.8% of divinylbenzene, formed a stable complex in chloroform with boron trifluoride containing 0.11% of boron, while cross-linked polystyrene-4-vinylpyridine resins containing 2–2.5% of pyridine rings formed a stable complex with boron trifluoride, containing 1.04% of boron. Both complexes catalyze conversions of aromatic aldehydes, ketones, and acids with alcohols into corresponding acetals, cyclic ketals, and esters; diphenylmethanol converts into ether. The structure of the alcohol plays an important role, with conversions decreasing in the order 1-butanol, 2-butanol, tert-butanol. Both complexes are very stable and in most cases more reactive than the cross-linked polystyrene-A1C1₃ complex.     

Aromatic Polyhedral Hydroxyborates: Bridging Boron Oxides and Boron Hydrides

No explosion , but per-B-hydroxylation occurs if the icosahedral boron hydrides [closo-B₁₂H₁₂]²⁻ (see picture), [closo-CB₁₁H₁₂]⁻, or closo-1,12-(CH₂OH)₂-1,12-C₂B₁₀H₁₀ are refluxed in 30 % hydrogen peroxide. Thus, the three isoelectronic species [closo-B₁₂(OH)₁₂]²⁻, [closo-1-H-1-CB₁₁(OH)₁₁]⁻, and closo-1,12-H₂-1,12-C₂B₁₀(OH)₁₀ were obtained. ○=BH, ○=BOH.     

Boron Carbide Secrets

Russian Journal of General Chemistry - The issues of the composition-structure relationship of boron carbide are discussed. A new hypothesis based on the presence of channels with a diameter of...     

Boron Separation by the Two—step Ion—Exchange for the Isotopic Measurement of Boron

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Boron—nitrogen compounds : LXX. Boron derivatives of 3,3′-diaminodipropylamine

The reaction of borane(3) with 3,3′-diaminodipropylamine yields BH₂B-bridge associated [3,3′-bis(dihydroborylamino)dipropylamino]dihydroborane, 1-aminopropyl-1,3,2-diazaboracyclohexane, or 1,8,10,9-triazaboradecalin (I), depending on the reaction conditions and the stoichiometry of the reactants. If tris(dimethylamino)borane is treated with 3,3′-diaminodipropylamine, only I or 1-bis-(dimethylamino)boryl-1,8,10,9-triazaboradecalin are obtained.     

Boron derivatives of dithiophosphoric acids

The reactions of tetraphosphorus decasulfide 1 with trialkyl borates 2a,b and O‐isobutyl diphenylborate 2c were studied. On the basis of these studies, a novel method of synthesizing S‐boron derivatives of dithiophosphoric acids was developed. The use of low frequency ultrasonic irradiation (22 kHz, power 130 W) leads to a reduction in reaction temperature and time required for completion of the reactions studied. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:102–106, 2000     

Boron complexes of pyrrolyl ligands

Complexes of boron with ligands containing pyrrolyl motifs are surveyed. The ligands range from simple pyrrolyl groups to dipyrroles and linear terpyrroles. Macrocyclic ligands include tripyrroles, which encompass subphthalocyanines, subporphyrins, subtriazaporphyrins, and subtribenzoporphyins, the familiar tetrapyrroles porphyrin and corrole but also N-confused and -fused porphyrins, and expanded porphyrins containing up to eight pyrroles. The role of boron in these compounds depends on the nature of the ligand. Boron acts as a Lewis acid center in simple boron pyrrolyl compounds, and as a structure-directing and templating agent in the cyclic terpyrroles and some of the expanded porphyrins. The difluorboron dipyrrins are well-known as fluorescent dyes. Boron porphyrins and corroles are unusual in containing two coordinated boron atoms rather than the single coordinated atom usually occurring in these ligands, and the proximity of two boron atoms at close quarters in the ligand cavities gives rise to some unusual reaction and redox chemistry. The survey is organized by the number of pyrrole moieties occurring in the ligand and focuses on new and unique chemistry observed for the complexes.     

硫代脯氨酸含硼配合物研究

具有抗癌作用的硫代脯氨酸可作为双齿配体与具有类金属属性的二芳基硼形成螫合物.本文报道9种这类新配合物,研究了IR、MS、NMR波谱.除配合物2和9外,这类配合物大都产生由于明显的芳基偶联作用而出现的碎片峰.     

Stable Boron Dithiolene Radicals

Whereas low‐temperature (?78 °C) reaction of the lithium dithiolene radical 1 ^. with boron bromide gives the dibromoboron dithiolene radical 2 ^., the parallel reaction of 1 ^. with (C₆H₁₁)₂BCl (0 °C) affords the dicyclohexylboron dithiolene radical 3 ^.. Radicals 2 ^. and 3 ^. were characterized by single‐crystal X‐ray diffraction, UV/Vis, and EPR spectroscopy. The nature of these radicals was also probed computationally. Under mild conditions, 3 ^. undergoes unexpected thiourea‐mediated B?C bond activation to give zwitterion 4 , which may be regarded as an anionic dithiolene‐modified carbene complex of the sulfenyl cation RS⁺ (R=cyclohexyl).     

Zeolitic Boron Imidazolate Frameworks

B‐hive? A family of crystalline materials analogous to porous AlPO₄ but based on boron imidazolate frameworks (BIFs) can be formed by the crosslinking of various presynthesized boron imidazolates with monovalent cations (Li⁺ and Cu⁺, see picture). This synthetic method is capable of generating a large variety of open frameworks, ranging from the four‐connected zeolitic sodalite type to the three‐connected chiral (10,3)‐a type.

     

Boron carbide-copper infiltrated cermets

Porous boron carbide preforms, prepared with and without excess carbon, were infiltrated with a Cu-Si alloy. Contrary to unalloyed copper, the Cu-Si alloy wets and infiltrates the porous preforms. A thermodynamic analysis of the B-C-Cu-Si system indicated that a Si content of the alloy above 15 at% leads to the formation of SiC. At higher Si content, the composition of boron carbide in contact with the melt also changes towards higher boron content. Metallographic examination validated these conclusions. The SiC compound forms preferentially around the free carbon particles in preforms containing excess carbon, and also in the vicinity of carbide that did not contain any excess carbon. Eventually, SiC, a product of the reaction between the carbide and the melt, forms a continuous barrier that impedes completion of the reaction and accounts for the limited increase of hardness as a result of lengthy heat treatments.