二十面体壳层结构——纪念C60发现10周年

圆顶建筑、病毒衣壳和C₆₀分子·笼的生成机制和尺寸差别很大，但都属二十面体壳层，遵循同一几何规律。圆顶建筑和病毒衣壳由近似全等的三角面构成，有12个五键连3⁵顶，10（T-1)个六键连3⁶顶，其中三角面数T=h²+hk十k²是二十面体的一个三角中的小三角面数，h,k是六角坐标系中3⁵顶的坐标。另一方面，全碳分子笼C_n(包括其原型C₆₀)由12个五角面与10(T-1)个六角面围成，全是三键连顶(h,k是一个五角面中心的坐标)。显然，这两类二十面体壳层是对偶的，也就是它们的面、顶有互换关系。本文讨论这些二十面体壳层的几何特征及富勒烯的多样性，强调不同学科间的联系和科学研究的继承与发展的关系。     

Energetics of Nucleation for the Icosahedral Al–Mn Phase in HTSD-Deposited Thin Films

The cohesive energy of the Al–Mn Mackay icosahedron (MI) was estimated for different variants of chemical order, using pair-bonding energies. This problem is related to the nucleation of i-AlMn phase in sequentially deposited thin films. The chemically ordered MI comes out as the thermodynamically most stable configuration. The role of kinetic factors during deposition is also discussed.     

Theoretical Analysis of the Mackay Icosahedral Cluster Pd55(PiPr3)12(μ3-CO)20: An Open-Shell 20-Electron Superatom

The electronic structure of the spherical Mackay icosahedral nanosized cluster Pd₅₅(PiPr₃)₁₂(μ₃-CO)₂₀ is analyzed by using DFT calculations. Results reveal that it can be considered as a regular superatom with a “magic” electron count of 20, characterized by a 1S² 1P⁶ 1D¹⁰ 2S² jellium configuration. Its open shell nature is associated with partial occupation of non-jellium, 4d-type, levels located on the interior of the Pd₅₅ kernel. This shows that the superatom model can be used to rationalize the bonding and stability of spherical ligated group 10 clusters, despite their apparent 0-electron count.     

Mackay Groups and Their Applications

Mackay groups (or compound groups) are considered in the historical context, as one of two possible kinds of multiple antisymmetry. The number of junior Mackay groups of M ^m type is calculated for different nonisomorphic antisymmetric characteristics formed by 1 l 4 generators. Combinatorial relationships connecting Mackay and Zamorzaev multiple antisymmetry groups are established. Geometrical applications of Mackay groups making possible direct dimensional transition from n-dimensional symmetry groups to (n + 2) dimensional subperiodic symmetry groups are discussed. Some open problems connected with Mackay groups are given.     

(SiO2)n团簇的基态能量和结构

应用遗传算法对二氧化硅团簇（SiO2）n（n≤20）的结构进行了优化计算。分析讨论了结构和结合能随团簇尺寸的变化规律,发现（SiO2）n团簇系列不存在明显的幻数,并在n≤20的范围内,不呈现出相应大块物质的结构特征,     

Electron－rich Polynuclear Transition Metal Clusters：Ⅱ．Synthetic and Structural Studies of Some Polynuclear Coinage Metal Cluster Compounds

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Ground State Structures,Electronic and Magnetic Properties of ScnFe (n=2–10) Clusters

The authors predict that the magnetic moment of the scandium clusters can not be efficiently enhanced with the encapsulation of Fe atom, which is different from previous works with Fe atom doped in B_n, Si_n, and Ge_n clusters. It was found that starting from n=6, the growth patterns of the ground state structures of the Sc_nFe clusters are dominated by the octahedron structures with Fe atom falling into the center of the host framework. The calculated results manifest that doping of the Fe atom contributes to strengthening the stabilities of the scandium framework. Maximum peaks are observed for clusters of n=3, 6 and 8 on the size dependence of the second‐order energy differences, implying that these clusters possess relatively higher stability. The HOMO‐LUMO gap of the Sc_nFe clusters exhibits an oscillational odd‐even character with the local peaks of n=4, 6 and 8. Especially, there is the largest oscillation of the gap with n=4 and 5. Additionally, the doped Fe atom exhibits the antiferromagnetic alignment at n=4, 5, 7 and 9. Also, the quench of the magnetic moments as n=6, 8 and 10 may be ascribed to the model of close‐shell electrons.     

Nucleation,growth, and fractal dimensions of icosahedral and polyicosahedral clusters

In this paper, the concept offractal geometry was applied to the growth of icosahedral and polyicosahedral clusters. Fractal dimensions were calculated for high-frequency icosahedral casters, vertex-sharing polyicosahedral clusters, and linked polyicosahedral clusters. These cluster growth pathways were compared with the fractal growth mechanisms of colloidal particles. Close similarities were found despite the tremendous differences in particle sizes and the forces governing their nucleation and growth processes.Dedicated to Prof. Lawrence F. Dahl on his 65th birthday; based in part on a lecture presented by BKT at the Dahl symposium held at the University of Wisconsin, Madison, Wisconsin on September 17, 1994.     

二十面体壳层结构：纪念C60发现10周年

圆顶建筑、病毒衣壳和Ｃ６０分子笼的生成机制和尺寸差别很大，但都属二十面体壳层，遵循同一几何规律。圆顶建筑和病毒衣壳由近似一等的三角面构成，有１２个五键加３＾５顶，１０（Ｔ－１）个六键连３＾６顶，其中三角面数Ｔ＝ｈ＾２＋ｈｋ＋ｋ＾２是二十面体的一个三角面中的小三角面数，ｈ，ｋ是六角坐标系中３＾５顶的坐标。另一方面，全碳分子笼Ｃｎ（包括其原型Ｃ６０），由１２个五角面与１０（Ｔ－１）个六角面围成，全是三     

Geometry,Vibrational and NMR Spectra of Icosahedral 1-Methylazacloso-dodecaborane

Geometry, vibrational and NMR spectra of the icosahedral aza-closo-dodecaborane MeNB₁₁H₁₁ are calculated by ab initio methods. The results are compared with experimental data. They are in accord with local C_5v symmetry of the cluster unit and local C_3v symmetry of the methyl group. The boron atoms B7–B11 are coupled to B12 by the small constant ¹J (¹¹B, ¹¹B) = 12 Hz.     

TiP+6, Ti2P+6二元团簇的密度泛函理论研究

利用含有电子相关效应校正的密度泛函理论DFT中的B3LYP方法，选择LANL2DZ双ξ基组，并考虑极化函数，对TiP6^ ,Ti2P6^ 二元团簇各种可能存在的几何构型及电子结构进行了密度泛函理论研究，得到了TimPn^ 二元团簇的最稳定构型，其中TiP6^ 的最稳定构型为具有C3v对称性的半笼状结构，Ti2P6^ 的最稳定构型为具有D6h对称性的六角双锥，所得构型很好地说明了激光光解的实验结果。     

Core–Shell Capsules Based on Supramolecular Hydrogels Show Shell‐Related Erosion and Release Due to Confinement

Hydrogel‐containing core–shell capsules are useful as drug delivery vehicles for many biomedical applications, especially when release of incorporated guests can be controlled. Here, we developed a one‐step organic solvent‐free method to prepare such core–shell capsules using a synthetic and a natural supramolecular hydrogel, for the core and shell, respectively. A solution containing ureido‐pyrimidinone modified poly(ethylene glycol) hydrogelators and calcium chloride was drop‐wise added to an alginate solution, yielding core–shell structures. It was found that the outer shell provides a confined space for the inner supramolecular hydrogel and therefore prevents swelling of the core. This consequently slows down both erosion of the less stable core, and release of dextran guests.

     

硼氢及客体二十面体簇合物的结构和稳定性

在(n=0、－1、－2、－3、－4)簇合物几何构型及稳定性研究的基础上,进一步对它的各种内含式和外 接式二十面体簇合物(X@B12H122－和XB12H122－,X=H0/＋、Li0/＋、He、Ne、Be0/2＋、Na＋、Mg2＋)进行了优化和 计 算.发现在内含式结构X@ B12H122－中,当X=Li＋、Be2＋、Mg2＋时,构型较稳定;在外接式结构中, XB12H122－(C3v)结构比XB12H122－(C2v)的结构稳定.通过IRC计算,确定XB12H122－(C2v)是X与B12H122－作用生成产物XB12H122－(C3v)的一种过渡态.     

Basic [Au25(SCH2CH2Py)18]−⋅Na+ Clusters: Synthesis,Layered Crystallographic Arrangement,and Unique Surface Protonation

The synthesis of high‐purity and high‐yield Au₂₅ clusters protected by the basic pyridyl ethanethiol (HSCH₂CH₂Py, 4‐PyET and 2‐PyET) is presented. Single‐crystal X‐ray diffraction of the [Au₂₅(4‐PyET)₁₈]^??Na⁺ clusters has revealed a structure similar to that known for the phenyl ethanethiolate analogue, but with pyridyl‐N coordination to Na⁺, a more relaxed ligand shell, and a profoundly layered arrangement in the solid state. Because of the pendant Py moiety, the [Au₂₅(PyET)₁₈]^? clusters are endowed with unique (de)protonation equilibria, which has been characterized in detail by UV/Vis absorption and ¹H NMR spectroscopy. [Au₂₅(PyET)₁₈]^? clusters showed an unexpectedly H⁺‐dependent solubility that is tunable in aqueous and organic solvents. The successful synthesis of the basic Py‐terminated thiolate‐protected Au₂₅ clusters paves the way to realize a new family of metalloid clusters possessing basic properties.     

Structural, Electronic, and Optical Properties of Noble Metal Clusters from First Principles

We examine low-energy isomeric forms, static polarizabilities, and optical absorption spectra of Ag _n , n = 2–8, and Au _n , n = 2–3, clusters using first principles computations within the static and time-dependent versions of the density functional theory. The noticeable decrease in the static polarizabilities of Ag₇ and Ag₈ compared to the values characteristic of Ag _n , n = 2–6, is correlated with the transition from two-dimensional to three-dimensional structures at n = 7. The optical spectra computed within the time-dependent local density approximation for the most stable structures are in good agreement with the available experimental data and the results of earlier theoretical studies. Optical spectra of higher-energy isomers typically present features that are not observed in the experimental spectra. The d electrons affect the spectra of noble metal clusters by quenching the oscillator strengths through screening of the s electrons and by getting directly involved in the excitations. Due to the larger s–d hybridization in Au compared to Ag, these effects are more pronounced in Au _n clusters.     

Synthesis,characterization, and some electrocatalytic properties of heteromultinuclear FeI/RuII Clusters

A series of new heteromultinuclear Fe^I/Ru^II clusters are described. The complexes (η⁶-arene)RuFe₂S₂(CO)₆ (arene = p-cymene 1 , C₆Me₆ 2 ) and Fe₂[μ-S (Cp*Ru)(CO)₂]₂(CO)₆ (Cp* = η⁵-C₅Me₅) ( 3 ) were prepared by the reduction reactions of (μ-S)₂Fe₂(CO)₆ with 2 equiv of LiHBEt₃, followed by treatment (μ-SLi)₂Fe₂(CO)₆ with ruthenium-arene complexes Ru₂(μ-Cl)₂Cl₂(η⁶-arene)₂ or Cp*Ru (CO)₂Cl in 22–33% yields. Further reactions of 1 and 2 with 1 equiv of triphenylphosphine in the presence of the decarbonylating agent Me₃NO·2H₂O, afforded the corresponding monophosphine-substituted Fe^I/Ru^II complexes (η⁶-arene)RuFe₂S₂(CO)₅(Ph₃P) (arene = p-cymene 4 , C₆Me₆ 5 ) in 75% and 78% yields. While treatment of parent complex 1 or 2 with 1 equiv of diphosphine Ph₂PCH₂PPh₂ (dppm) in xylene at reflux temperature resulted in the formation of the diphosphine-bridged RuFe₂S₂(CO)₉ derivate RuFe₂S₂(CO)₇(dppm) ( 6 ). The possible pathway for the formation was proposed. Two isomers of novel macrocyclic complexes involve the (η⁶-arene) Ru-bridged quadruple-butterfly Fe/S clusters [{μ-S (CH₂)₃S-μ}{(μ-CS₂)Fe₂(CO)₆}₂]₂[(η⁶-arene)Ru]₂ (arene = p-cymene 7a and 7b , C₆Me₆ 8a and 8b ) were isolated by reactions of two μ-CS₂-containing dianion [{μ-S (CH₂)₃S-μ}{(μ-S=CS)Fe₂(CO)₆}₂]²⁻ with [Ru₂(μ-Cl)₂Cl₂(η⁶-arene)₂], in which the propylene groups are attached to two S atoms by ee and ea types of bonds respectively. All the new complexes 1 – 8 have been characterized by elemental analysis, spectroscopy, and particularly for 1 – 6 , 7b and 8a by X-ray crystallography. In addition, the electrochemical properties of representative complexes 1 – 4 and 6 have been investigated.     

正二十面体Au13和Pt13团簇上肉桂醛的吸附

运用广义梯度近似(GGA)密度泛函理论的Perdew-Burke-Ernzerh (PBE)方法, 研究了肉桂醛在正二十面体Au₁₃和Pt₁₃团簇上的吸附行为. 通过分析不同吸附模式的吸附能和几何构型发现: 同一金属团簇, 顺式肉桂醛的吸附能强于反式肉桂醛的吸附能. 对于Au₁₃团簇, 肉桂醛的稳定吸附构型为C＝C和C＝O共吸附模型; 对于Pt₁₃团簇, 肉桂醛的稳定吸附构型为C＝O吸附. 比较二者发现, 肉桂醛在Pt₁₃团簇的吸附能力强于Au₁₃团簇.分析Au₁₃和Pt₁₃团簇上肉桂醛最稳定吸附构型的电子结构表明, 电子由肉桂醛原子的2s、2p轨道向金属表面转移, 同时金属部分电子反馈到肉桂醛的反键轨道, 最终肉桂醛稳定吸附于金属团簇. 此外, 肉桂醛在团簇模型上的吸附能大于其在平板模型上的吸附能.