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1.
The first synthesis of BePh2 was accomplished almost a century ago. However, its structure has remained unknown so far, while the corresponding aryls of the elements adjacent to beryllium in the periodic table are well investigated. Herein, we present an improved synthesis for diphenylberyllium and show by X-ray diffraction that it forms a trinuclear complex in the solid state. NMR spectroscopy revealed that this structure is also retained in solution but exhibits dynamic behavior. Its stability against heat and coordinating solvents is discussed and the possible obstacles to the synthesis of BePh2 from BeCl2 are examined. In the process of this study two ether adducts, BePh2⋅Et2O and Be2Ph4⋅Et2O, have been characterized as well as the previously unknown triphenylberyllate anion. From the latter several single-crystal structures were obtained under various conditions, in which [BePh3] is either isolated or acts as a ligand for Li+. Furthermore, the crown ether induced selfionization of BePh2 is described and the resulting [(12-crown-4)BePh]+ cation was isolated, which shows an unusual 4+1 coordination around the Be atom.  相似文献   
2.
The possibility of forming stable BeR2:ArH:Y? (R=H, F, Cl; ArH=naphthalene, pyrene; Y=Cl, Br) ternary complexes in which the beryllium compounds and anions are located on the opposite sides of an extended aromatic system is explored by means of MP2/aug‐cc‐pVDZ ab initio calculations. Comparison of the electron‐density distribution of these ternary complexes with the corresponding BeR2:ArH and ArH:Y? binary complexes reveals the existence of significant cooperativity between the two noncovalent interactions in the triads. The energetic effects of this cooperativity are quantified by evaluation of the three‐body interaction energy Δ3E in the framework of the many‐body interaction‐energy (MBIE) approach. Although an essential component of the interaction energies is electrostatic and is well reflected in the changes in the molecular electrostatic potential of the aromatic system on complexation, strong polarization effects, in particular for the BeR2:ArH interactions, also play a significant role. The charge transfers associated with these polarization effects are responsible for significant distortion of both the BeR2 and the aromatic moieties. The former are systematically bent in all the complexes, and the latter are curved to a degree that depends on the nature of the R substituents of the BeR2 subunit.  相似文献   
3.
Using high-resolution transmission electron microscopy and electron energy-loss spectroscopy, we show that beryllium oxide crystallizes in the planar hexagonal structure in a graphene liquid cell by a wet-chemistry approach. These liquid cells can feature van-der-Waals pressures up to 1 GPa, producing a miniaturized high-pressure container for the crystallization in solution. The thickness of as-received crystals is beyond the thermodynamic ultra-thin limit above which the wurtzite phase is energetically more favorable according to the theoretical prediction. The crystallization of the planar phase is ascribed to the near-free-standing condition afforded by the graphene surface. Our calculations show that the energy barrier of the phase transition is responsible for the observed thickness beyond the previously predicted limit. These findings open a new door for exploring aqueous-solution approaches of more metal-oxide semiconductors with exotic phase structures and properties in graphene-encapsulated confined cells.  相似文献   
4.
建立了电感耦合等离子体原子发射光谱法(ICP-OES)测定铍铀伴生矿石中的铍的方法,研究了酸溶-碱熔融法溶样过程中加入的焦硫酸钾,对ICP-OES法测定铍铀伴生矿石中的铍含量产生的基体干扰问题。主要阐述消除基体干扰的一些措施。从实验数据可知,控制称样量、焦硫酸钾加入量、定容体积和加标稀释倍数,能够有效消除焦硫酸钾对ICP-OES法测定结果的基体干扰,6次平行测定结果的相对标准偏差为3.4%,加标回收率为98.7%~104.4%,实验表明,方法准确、可靠。  相似文献   
5.
Beryllium fluorides are widely used in protein phosphorylation studies to get stable transition state analogs or near attack conformers, which has attracted much attention. BeF3? is one of the optimal phosphoryl (PO3?) analogs for its identical geometry and charge, and Mg2+ naturally participates in the phosphoryl binding in biological systems. In solutions, BeF3? coexists with other beryllium fluorides (BeF42?, BeF2 and BeF+) and magnesium fluorides, and there are equilibriums between these species. In this article, 19F NMR spectroscopy was applied to the investigation of the impact of magnesium(II) on beryllium fluorides. It has been found that when Mg2+ was introduced into the solutions, the chemical shifts, the intensities and the line widths of 19F signals of various beryllium fluoride complexes were changed. After ionic strength correction, these effects were remarkable only for BeF42? and BeF3?, especially BeF42?, when the concentration of the fluoride ion is relatively low. Mechanism of the effects is proposed which involves ion pair formation between Mg2+ and beryllium fluorides.  相似文献   
6.
The first structural characterization of the text‐book tetraammineberyllium(II) cation [Be(NH3)4]2+, obtained in the compounds [Be(NH3)4]2Cl4 ? 17NH3 and [Be(NH3)4]Cl2, is reported. Through NMR spectroscopic and quantum chemical studies, its hydrolysis products in liquid ammonia were identified. These are the dinuclear [Be2(μ‐OH)(NH3)6]3+ and the cyclic [Be2(μ‐OH)2(NH3)4]2+ and [Be3(μ‐OH)3(NH3)6]3+ cations. The latter species was isolated as the compound [Be3(μ‐OH)3(NH3)6]Cl3 ? 7NH3. NMR analysis of solutions of BeF2 in liquid ammonia showed that the [BeF2(NH3)2] molecule was the only dissolved species. It acts as a strong fluoride‐ion acceptor and forms the [BeF3(NH3)]? anion in the compound [N2H7][BeF3(NH3)]. The compounds presented herein were characterized by single‐crystal X‐ray structure analysis, 9Be, 17O, and 19F NMR, IR, and Raman spectroscopy, deuteration studies, and quantum chemical calculations. The extension of beryllium chemistry to the ammine system shows similarities but also decisive differences to the aquo system.  相似文献   
7.
Abstract

The emission spectra of isotopic BeO molecules as excited in low-pressure arc have been photographed in the region 300–350 nm at medium dispersion. The bands have been assigned to the c3II ? a3II system. The vibrational numbering was obtained from a study of the vibrational isotope effect. Vibrational constants for involved states are derived from least-squares fits of the measured bandhead wavenumbers.  相似文献   
8.
The electronic bands appearing in the region 300–330 nm were produced in a low-pressure DC are with beryllium electrodes. The bands were obtained in the atmosphere of ordinary water vapour and heavy water vapour. From isotope shift studies, experimental conditions and the similarity with the bands of isoelectronic BeF, the emitting molecules were identified as BeOH and BeOD, respectively.  相似文献   
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