5-羧基偶氮胂Ⅰ测定铍的研究

本文研究了试剂5-羧基偶氮胂I与铍的显色反应。试剂与铍在557nm形成1∶1络合物,其反应的酸度pH为5.3～6.2,毫克量级的干扰离子存在不干扰测定。该试剂可不加任何掩蔽剂,直接测定水样及锌基合成样中的铍。     

Be3Ru: Polar Multiatomic Bonding in the Closest Packing of Atoms

The new phase Be₃Ru crystallizes with TiCu₃-type structure (space group Pmmn (59), a=3.7062(1) Å, b=4.5353(1) Å, c=4.4170(1) Å), a coloring variant of the hexagonal closest packing (hcp) of spheres. The electronic structure revealed that Be₃Ru has a pseudo-gap close to the Fermi level. A strong charge transfer from Be to Ru was observed from the analysis of electron density within the Quantum Theory of Atoms in Molecules (QTAIM) framework and polar three- and four-atomic Be−Ru bonds were observed from the ELI−D (electron localizability indicator) analysis. This situation is very similar to the recently investigated Be₅Pt and Be₂₁Pt₅ compounds. The unusual crystal chemical feature of Be₃Ru is that different charged species belong to the same closest packing, contrary to typical inorganic compounds, where the cationic components are located in the voids of the closest packing formed by anions. Be₃Ru is a diamagnet displaying metallic electrical resistivity.     

Ternary Complexes Stabilized by Chalcogen and Alkaline-Earth Bonds: Crucial Role of Cooperativity and Secondary Noncovalent Interactions

High-level G4 calculations show that the strength of chalcogen interactions is enhanced dramatically if chalcogen compounds simultaneously form alkaline-earth bonds. This phenomenon is studied by exploring binary YX₂⋅⋅⋅N-Base complexes and two types of ternary MCl₂⋅⋅⋅YX₂⋅⋅⋅N-Base, YX₂⋅⋅⋅N-Base⋅⋅⋅MCl₂ complexes, in which YX₂ is a chalcogen compound (Y=S, Se; X=F, Cl), the N-Bases are sp, sp², and sp³ bases (NCH, HN=CH₂, NH₃), and MCl₂ are alkaline-earth BeCl₂ or MgCl₂ derivatives. Starting from the chalcogen-bonded complexes YX₂⋅⋅⋅NH₃ and YX₂⋅⋅⋅HN=CH₂, the binding site of a new incoming alkaline-earth bond is found, surprisingly, to depend on the nature of the halogen atom attached to the chalcogen. For the YF₂ binary complexes the association site is the F atom of the YF₂ subunit, whereas for YCl₂ it is the N atom of the nitrogen base. Regarding YX₂⋅⋅⋅NCH complexes, N is the most favorable site for an alkaline-earth interaction in ternary complexes, regardless of which YX₂ derivative is used. The explanation relies on the interplay of all the noncovalent interactions involved: the strong cooperativity between chalcogen and alkaline-earth bonds, and the appearance of secondary noncovalent interactions in the form of hydrogen bonds.     

Complexes between H2 and neutral oxyacid beryllium derivatives. The role of angular strain

ABSTRACT

The complexes between 14 different Be-salts of oxyacids from groups 13 to 16 with one and two molecules of H₂ have been investigated by means of the MP2/aug-cc-pVTZ ab initio molecular orbital theory method, which was found to be reliable for the treatment of these weakly bound species. The main conclusion is that these Be-salts yield rather stable complexes with dihydrogen, with binding energies one order of magnitude larger than other typical H₂ complexes reported in the literature. This strong binding is shown to be due to an enhancement of the electron-deficient nature of Be when attached to an oxyacid moiety, which depends more on the type of coordination of the central atom of the oxyacid moiety. The formation of these complexes is followed by a significant lengthening of the H₂ internuclear distance and a concomitant red-shift of the H–H stretching frequency, which becomes a good indicator of the strength of the interaction. The charge shifting from the bonding region of the H₂ molecule to the interboundary Be···H₂ region is the physical phenomenon behind the stability of these complexes. Accordingly, the most important contributor to this stability is the inductive term, followed by the electrostatic interactions. The ability of Be to bind H₂ is enhanced by the angular arrangement of the O–Be–O electron-acceptor group.     

Computational Study of spx(x=1–3)-Hybridized Be−Be Bonds Stabilized by Amidinate Ligands

Complexes containing odd-electron Be−Be bonds are still rare until now. Hereby, a series of neutral di-beryllium amidinate complexes containing a Be−Be bond were explored theoretically. The complexes with direct chelation with the Be₂ dimer by the bidentate amidinate (AMD) ligands are always corresponding to their global minimum structures. The detailed bonding analyses reveal that the localized electrons of the Be−Be fragment can be adjusted by the amount of AMD ligands because each AMD ligand only takes one electron from the Be₂ fragment. Meanwhile, the hybridization of the central Be atom also changes as the number of AMD ligands increases. In particular, the sp³-hybridized single-electron Be−Be bond is firstly identified in the tri-AMD-ligands-chelated neutral D_3h- Be₂(AMD)₃ complex, which also possesses the higher stability compared to its monoanionic D_3h- Be₂(AMD)₃ ⁻ and monocationic C₃- Be₂(AMD)₃ ⁺ analogues. Importantly, our study provides a new approach to obtain a neutral odd-electron Be−Be bond, namely by the use of radical ligands through side-on chelation.     

9Be and 31P NMR analyses on the influence of imino groups on Be2+ complex stabilities of a series of cyclo‐μ‐imido triphosphate anions

The complexation behaviors of Be²⁺ with cyclo‐μ‐imido triphosphate anions, cP₃O_9?n(NH)_n^3? (n = 1, 2), have been investigated by both ⁹Be and ³¹P NMR techniques at ?2.3 °C in order to clarify the coordination structures of the complexes. The spectra showed that cP₃O_9?n(NH)_n (n = 1, 2) ligands form ML, ML₂, and M₂L complexes with Be²⁺ ions, and the formation of complexes coordinating with nitrogen atoms of the cyclic framework in the ligand molecule has been excluded. These complexation trends are very similar to those of Be²⁺‐cP₃O₆(NH)₃^3? system, which has been reported by us. The peak deconvolution of ⁹Be NMR spectra made these beryllium complexes amenable to stability constant determinations. The stability constants of the complexes increase with an increase in the protonation constants of the ligands as the number of imino groups, which constitute the ligand molecules, is ascended. This increase is primarily attributable to the lower electronegativity of nitrogen atoms than oxygen atoms, which are directly bonded to central phosphorus atoms; moreover, tautomerism equilibrium in the entire of the imidopolyphosphate molecule is also responsible to the higher basicity. ³¹P NMR spectra measured concurrently have verified the formation of the complexes estimated by the ⁹Be NMR measurement. Intrinsic ³¹P NMR chemical shift values of the phosphorus atoms belonging to ligand molecules complexed with Be²⁺ cations have been determined. Not only the protonation constants but also the stability constants of all Be²⁺ complexes increase approximately linearly with an increase in the number of imino groups. Copyright © 2013 John Wiley & Sons, Ltd.     

First Data on 10Be in Recent Volcanics of the Kurile-Kamchatka Island Arc System in Relation to Sediment Subduction

Concentrations of ¹⁰ Be were measured in 23 lava samples representing historically and ¹⁴C dated eruptions of major Kurile and Kamchatka volcanoes. We report 2.2–7.9 · 10⁶ at/g of ¹⁰Be for Kuriles and in most cases less than 1.2 · 10⁶ at/g for Kamchatka. Thus Kurile segment of the Kurile-Kamchatka arc system features the same isotopic pattern as the Aleutians and some continental arcs like Central America and the Andes. The obtained results confirm previously drawn conclusion that the scale of sediment incorporation in Kurile magmas is not large thought the process itself is quite real.     

Synthesis and Characterization of a Magnesium Boryl and a Beryllium‐Substituted Diazaborole

Reaction of a lithium boryl, [(THF)₂Li{B(DAB)}] (DAB=[(DipNCH)₂]^2?, Dip=2,6‐diisopropylphenyl), with a dinuclear magnesium(I) compound [{(^MesNacnac)Mg}₂] (^MesNacnac=[HC(MeCNMes)₂]^?, Mes=mesityl) unexpectedly afforded a rare example of a terminal magnesium boryl species, [(^MesNacnac)(THF)Mg{B(DAB)}]. Attempts to prepare the magnesium boryl via a salt metathesis reaction between the lithium boryl and a β‐diketiminato magnesium iodide compound, instead led to an intractable mixture of products. Similarly, reaction of the lithium boryl with a β‐diketiminato beryllium bromide precursor, [(^DepNacnac)BeBr] (Dep=2,6‐diethylphenyl) did not give a beryllium boryl, but instead afforded an unprecedented example of a beryllium substituted diazaborole heterocycle, [{(^DepNacnac)Be(4‐DAB^?H)}BBr]. For sake of comparison, the same group 2 halide precursor compounds were treated with a potassium gallyl analogue of the lithium boryl, viz. [(tmeda)K{:Ga(DAB)}] (tmeda=N,N,N’,N’‐tetramethylethylenediamine), but no reactions were observed.     

Be薄膜应力的X射线掠入射侧倾法分析

由于铍薄膜极易被X射线穿透, 传统的几何模式下很难获得有效的X射线衍射应力分析结果. 本文采用掠入射侧倾法分析SiO₂基底上Be薄膜残余应力, 相比其他衍射几何方法, 提高了衍射的信噪比, 获得的薄膜应力拟合曲线线形较好. 对Be薄膜的不同晶面分析, 残余应力结果相同, 表明其力学性质各向同性; 利用不同掠入射角下X射线的穿透深度不同, 获得应力在深度方向上的分布; 由薄膜面内不同方向的残余应力相同, 确定薄膜处于等双轴应力状态. 关键词： Be薄膜 X射线衍射 应力     

A computational study of model hydrogen-, halogen-, beryllium- and magnesium-bonded complexes of aziridine derivatives

ABSTRACT

A computational study of the complexes F^?/H₂O…Z-aziridine, Z-aziridine…BeH₂/MgH₂ and F^?/H₂O…Z-aziridine…BeH₂ /MgH₂ (Z = Cl, H, Li) was undertaken in order to investigate the non-covalent interactions operative in the dimers and to assess their interplay in the trimer complexes. The halogen- and hydrogen-bonds between the O and Z atoms in F^?/H₂O…Z-aziridine are enhanced in the trimers by the Be(Mg) bond and vice versa, but the lithium bond is hardly affected. In the trimers containing F^?, the H bond is more dominant than the Be(Mg) bond, whereas the Be(Mg) bond is more dominant in the halogen- and lithium-bonded analogues. On the other hand, the Be(Mg) bond makes the major contribution to the energetic stability of all of the trimers containing H₂O.