The synthesis and reactivity of the heptanuclear dianion [Os7(CO)20]2− including the synthesis and structural characterizations of the compounds [Os7(CO)20(AuPEt)3 2] and [Os8(CO)20(η6-C6H6]

Reduction of the heptaosmium cluster [Os₇(CO)₂₁] With [Et₄N][NH₄) gives the cluster dianion [Os₇(CO)₂₀]^2–,1, in high yield. The reaction of the dianion with [AuPR ₃Cl] (R=Et or Ph) in the presence of TlPF₆ forms [Os₇((CO)₂₀(AuPR ₃)₂] [R=Et (2a);R = Ph(2b)] in 80% yield, while the corresponding reaction with (Os(C₆H₆)(CH₃CN)₃]²⁺ gives [Os₈(CO)₂₀ ( ⁶-C₆H₆)] (3) in reasonable yield (ca. 30%). The dianion,1, and the clusters2 and3 have been fully characterized by bout spectroscopic and crystallographic methods. The crystal structure of the [Ph₄P]⁺ salt of1 shows that the metals in the anion adopt a capped octahedral geometry, with all twenty carbonyl ligands in terminal sites. The metal core geometry in2a is best described as a tricapped octahedron, and is based on the structure of the dianion1 with two adjacent octahedral faces capped by the Au atoms of the two AuPEt₃ groups. In a similar fashion, the geometry of3 is related to that of1 with the addition of an Os(C₆H₆) unit capped to a triangular face, to give a bicapped octahedral framework.     

A multiple coupling approach to produce high-performance SERS substrates

In this work, large area gold-nanoparticle-cluster pillar array with a gold mirror as high-performance SERS substrate was facilely fabricated by combined use of nanosphere lithography and self-assembly approach.     

Synthesen und Kristallstrukturen von [Pd9As8(PPh3)8] und [Pd9Sb6(PPh3)8]

Syntheses and Crystal Structures of [Pd₉As₈(PPh₂)₈] and [Pd₉Sb₆(PPh₃)₈] [PdCl₂(PPh₃)₂] reacts with As(SiMe₃)₃ to give the new cluster [Pd₉As₈(PPh₃)₈] ( 4 ). 4 has been characterized by X-ray crystal structure analysis. It is a molecule in which four [Pd₂(PPh₃)₂]-units are bridged by As₂-units. A further Pd atom is located in the centre of the cluster. 4 crystallizes in the space group C2/c with four formula units per unit cell. The lattice constants at 200 K are: a = 3 970.6(3), b = 1 648.90(16), c = 3 266.30(20) pm, β = 131,44(4)°. The reaction of [PdCl₂(PPh₃)₂] with Sb(SiMe₃)₃ yields [Pd₉Sb₆(PPh₃)₈] ( 5 ). 5 consists of a body centred cubic Pd₉-cluster. All of the cube faces are capped by μ₄-Sb-ligands. 5 crystallizes in the space group Pn3 with two formula units per unit cell. The lattice constants at 200 K are: a = b = c = 1 995.4(2) pm.     

Cobalt Chalcogenide Clusters. Synthesis,Characterization and DFT Calculations of [Co4Se2(CO)10] and [Co4Te2(CO)11]. Crystal Structure of [Co8Se4(CO)16(μ‐dppa)2]

The reactions of [Co₂(CO)₈] with E(SiMe₃)₂ (E = Se, Te) in CH₂Cl₂ result in the formation of the compounds [Co₄Se₂(CO)₁₀]> ( 1 ) and [Co₄Te₂(CO)₁₁] ( 2 ), respectively. Both cluster complexes have similar molecular structures in which the cobalt atoms form four‐membered rings with μ₄‐bridging chalcogen atoms (Se and Te) above and below the plane of the metal atoms and the carbonyl ligands as either terminal or μ₂‐bridging ligands. DFT‐calculations for both compounds have been carried out in order to obtain some more information about their electronic distribution. In the presence of the phosphine Ph₂PC≡CPPh₂ (dppa), the reaction of [Co₂(CO)₈] with Se(SiMe₃)₂ leads to the formation of [Co₈Se₄(CO)₁₆(μ‐dppa)₂] ( 3 ). During the reaction two molecules of [Co₂(CO)₈] have been added to the acetylene groups of the dppa ligands, whilst the remaining cobalt atoms coordinate to the phosphorus atoms of the phosphine. In this compounds the selenium atoms act as μ₃‐ligands, bridging the metal atoms bonded to the phosphorus with those bonded to the acetylene groups.     

Synthesis and Crystal Structure of [C10N2H10]2[P2Mo5O21(OH)2]·2H2O

The crystal structure of [C₁₀N₂H₁₀]₂[P₂Mo₅O₂₁(OH)₂] · 2H₂O, contains the heteropolyanion, [P₂Mo₅O₂₁(OH)₂]^4—, together with diprotonated 4, 4′‐bipyridine. The heteropolyanion is built up from five MoO₆ octahedra sharing four common edges and one common corner, capped by two PO₃(OH) tetrahedra. The structure is stabilized by hydrogen bonds involving the hydrogen atoms of the 4, 4′‐bipyridine, water molecules and the oxygen atoms of the pentamolybdatobisphosphate. This is the first example that this kind of cluster could be isolated in the presence of a poly‐functional aromatic molecule ion. Crystal data: triclinic, P1¯ (No. 2), a = 9.983(2)Å, b = 11.269(2)Å, c = 17.604(4)Å, α = 73.50(3)°, β = 84.07(3)°, γ = 67.96(3)°; V = 1760.0(6)ų; Z = 2; R₁ = 0.037 and wR₂ = 0.081, for 9138 reflections [I > 2σ(I)].     

天津市各区县经济发展水平的多元统计分析

本文选取了10项适当的主要经济指标对天津市18个区（县）的经济发展水平进行系统聚类分析和主成分分析，综合评价了各区县的经济发展水平．     

不同地区毛泡桐种子发芽状况的初步研究

本文分析了不同地区毛泡桐种子的发芽状况并对其进行了系统聚类分析。结果表明，光照处理有利于提高毛泡桐种子的发芽率和发芽势，室温贮藏不利于种子活力的长期保持。根据不同条件下毛泡桐种子发芽率和发芽势的差别，利用系统聚类方法将其划分为四组，该结果为泡桐引种和培养新品种等奠定了基础。     

锡表面Mo(W)-S-Sn彩色簇合物膜的组成与结构研究

通过(NH4)2Mo(W)S4溶液浸渍,在金属Sn表面获得了不溶性且具有金属光泽的Mo(W)-S-Sn彩色簇合物膜。FT-IR、F-IR、FT-Raman、XPS和AES研究表明,簇合物膜中存在Mo(W)-S-Sn、端基Mo(W)-S和端基Mo(W)-O键,膜层由Mo(W)、S、Sn和O元素组成,膜为多分子层结构,从AES深度分布曲线的组成恒定区求得了元素的相对原子百分数和膜层厚度。     

The hidden disintegration of cluster heterogeneity in Fe-based glass-forming alloy melt

The evolution of liquid metal at high temperature is known much less than their solid states. This is partially due to that the message concerning clusters, metastable phase or heterogeneity in liquid is usually too slight to be traced. Here, we shed some light on the nature of structural evolution of Fe-based glass-forming alloy during overheating process by the investigation of high-temperature melt viscometry and first principles simulations. It was found that a structural transition around 1400 ℃ occurred in the melts of initial homogeneous ingot, heterogeneous ingot and amorphous ribbons jointly, and was confirmed by the results from differential scanning calorimeter(DSC), and ab initio molecular dynamics(AIMD). Combining these results with Fe-Si-B ternary phase diagram and the melting characteristics of Fe-B compounds, it is safe to conclude that the disintegration of Fe_2B type clusters to Fe_3B-type clusters leads to the observed transition. These results offer a significant reference for the preparation and property control of Fe-based amorphous alloys.