疏水分配常数用于反相液相色谱保留值的预测

在反相液相色谱保留值基本方程log k_′=a+_cC_B的基础上,描述了采用疏水分配常数及氢键作用能来预测a、c参数的方法,并系统讨论了疏水分配常数对参数a、c的影响,借此对反相液相色谱宽浓度范围内的保留值进行了预测。     

Tantalum Clusters in Oxidic Matrices — Synthesis,Crystal Structure and Magnetic Properties of Eu1.83Ta15O32

The mixed‐valent oxotantalate Eu_1.83Ta₁₅O₃₂ was prepared from a compressed mixture of Ta₂O₅ and the metals in a sealed Ta ampoule at 1400 °C. The crystal structure was determined by means of single crystal X‐ray diffraction: space group R3¯, a = 777.2(6) pm and c = 3523.5(3) pm, Z = 3, 984 symmetrically independent reflections, 83 variables, R_F = 0.027 for I > 2σ (I). The structure is isotypic to Ba₂Nb₁₅O₃₂. The salient feature is a [Ta(+8/3)₆O₁₂ⁱO₆^a] cluster consisting of an octahedral Ta₆ core bonded to 12 edge‐bridging inner and six outer oxygen atoms. The clusters are arranged to slabs which are sandwiched by layers of [Ta(+5)₃O₁₃] triple octahedra. Additional Ta(+5) and Eu(+2) atoms provide the cohesion of these structural units. Twelve‐fold coordinated Eu(+2) atoms are situated on a triply degenerate position 33 pm displaced from the threefold axis of symmetry. A depletion of the Eu(+2) site from 6 to 5.5 atoms per unit cell reduces the number of electrons available for Ta‐Ta bonding from 15 to 14.67 electrons per cluster. Between 125 and 320 K Eu_1.83Ta₁₅O₃₂ is semi‐conducting with a band gap of 0.23 eV. The course of the magnetization is consistently described with the Brillouin function in terms of a M_mol/(N_Aμ_B) versus B/T plot in the temperature range 5 K — 320 K and at magnetic flux densities 0.1 T — 5 T. At moderate flux densities (< 1 T) the magnetic moment agrees fairly well with the expected value of 7.94 μ_B for free Eu (2+) ions with 4f⁷ configuration in ⁸S_7/2 ground state. Below 5 K, anisotropic magnetization measurements at flux densities B < 1 T point to an onset of an antiferromagnetic ordering of Eu spins within the layers and an incipient ferromagnetic ordering perpendicular to the layers.     

Linear scaling local correlation approach for solving the coupled cluster equations of large systems

A linear scaling local correlation approach is proposed for approximately solving the coupled cluster doubles (CCD) equations of large systems in a basis of orthogonal localized molecular orbitals (LMOs). By restricting double excitations from spatially close occupied LMOs into their associated virtual LMOs, the number of significant excitation amplitudes scales only linearly with molecular size in large molecules. Significant amplitudes are obtained to a very good approximation by solving the CCD equations of various subsystems, each of which is made up of a cluster associated with the orbital indices of a subset of significant amplitudes and the local environmental domain of the cluster. The combined effect of these two approximations leads to a linear scaling algorithm for large systems. By using typical thresholds, which are designed to target an energy accuracy, our numerical calculations for a wide range of molecules using the 6-31G or 6-31G* basis set demonstrate that the present local correlation approach recovers more than 98.5% of the conventional CCD correlation energy.     

Uranium-sulfilimine chemistry. The preparation of Cp2*UCl2(HNSPh2) and its hydrolysis with HNSPh2 · H2O

The reaction of Cp₂*UCl₂ with HNSPh₂ produces Cp₂*UCl₂(HNSPh₂), which is the first structurally characterized complex of a sulfilimine. The hydrolysis of Cp₂*UCl₂(HNSPh₂) with HNSPh₂ · H₂O yields a tetrauranium cluster whose heavy atom structure has been determined by x-ray diffraction and which is formulated as a U^IV/U^V complex: [Cp*(Cl)(HNSPh₂)U(μ₃-O)(μ₂-O)₂U(Cl)(HNSPh₂)₂]₂.     

含磷、硫、氮配原子的钴羰基簇合衍生物的合成和表征

过渡金属原子簇化学是当今化学学科中非常活跃的研究领域之一 ,这类簇合物大多有着新颖的几何构型和多样化的成键方式 ,并且具有独特的催化性能[1 ] 。迄今为止 ,人们合成了多种含磷、硫、氮等原子的铁、钴、钌等羰基簇合衍生物 ,但其中三种以上原子同时配位的情况并不多见 ,有金振兴等的含Ｃ、Ｓ、Ｎ配原子的三核钴簇[2 ] ;Ｌｕｇａ和Ｃａｂｅｚａ的三钌簇[3 ,4] 以及Ｃｈｉｈａｒａ等合成的五核钌簇[5] ,其分子中都有Ｐ、Ｎ、Ｏ三原子配位。我们利用复杂的含Ｐ、Ｓ、Ｎ等可配原子的有机配前体与二元钴羰合物反应 ,合成了一系列三核、四核…     

Two 3D supramolecular polymers constructed from an amino acid and a high-nuclear Ln6Cu24 cluster node

The first successful attempt to construct 3D supramolecular frameworks with high-nuclear 3d-4f heterometallic clusters as a node is reported. The self-assembly of Ln3+, Cu2+ and amino acid in solution leads to the formation of two polymers, 35-nuclear complex [Sm6Cu29] 1 with a primitive cubic net-like structure and 36-nuclear complex [Nd6Cu30] 2 with a face-centred cubic network type structure. Glycine and L-proline, respectively, were used as ligands. It should be noted that 2 has a chiral framework. X-ray structure analyses show that 1 crystallizes in the triclinic P1 space group (a=19.6451(8), b=20.4682(8), c=20.7046(8) A, alpha=89.453(1), beta=66.290(1), gamma=68.572(1) degrees, V=7003.0(5) A3 and Z=1) and 2 belongs to the cubic P2(1)3 space group (a=b=c=32.4341(3) A, V=34 119.7(5) A3 and Z=4). Both complexes utilize Ln6Cu24 octahedral clusters as nodes and trans-Cu(amino acid)2 groups as bridges. Electrical conductivity measurements reveal that both polymers behave as semiconductors.     

<Emphasis Type="Italic">Ab initio</Emphasis> study of small coinage metal telluride clusters Au<Subscript>n</Subscript>Te<Subscript>m</Subscript> (<Emphasis Type="Italic">n,m</Emphasis> = 1, 2)

The geometries of the most stable isomers of gold telluride systems AuTe, Au₂Te, and AuTe₂ are determined using the MP2 method. The aspect of gold—telluride interaction, the electron correlation, and relativistic effects on geometry and stability are investigated at the MP2 and CCSD(T) theoretical levels. The results show that the electron correlation and relativistic effects are responsible not only for gold—gold attraction but also for additional gold—telluride interaction. The gold—telluride interaction is strong enough to modify the known pattern of bare gold clusters. Both effects are essential for determining the geometry and relative stability of this type of systems.     

钴膦簇合物的催化环丙烷化反应

本文首次利用碳基钴簇合物ＰｈＰＣｏ_３（ＣＯ）_９催化剂，在常压和－２０℃－０℃，用苯乙烯和重氮乙酸乙酯进行环丙烷化反应，合成了菊酸酯，重氮乙酸乙酯可全部转化，酯的选择性可达８５％。产物经减压分馏后，由ＩＲ和￣１ＨＮＭＲ分析，确证了产物为菊酸酯，表明了羰基钴簇合物对苯乙烯的环丙烷化反应有良好的催化性能，为四面体异核簇合物用于不对称催化反应打下了基础。     

Cluster Build-up Reactions using Di-gold Cationic Fragments: Synthesis and Structural Characterization of [Os7(CO)19(Au2dppm)]

The reaction of the di-gold cation [Au₂(dppx)]²⁺ with the heptanuclear cluster dianion [Os₇(CO)₂₀]^2– affords the mixed metal cluster [Os₇(CO)₂₀{Au₂(dppx)}] (x=m (1), e (2), b (3)). On standing, in solution, this complex undergoes decarbonylation to give the cluster [Os₇(CO)₁₉{Au₂(dppx)}] (x=m (4), e (5), b (6)). The complexes have been characterised spectroscopically, and an X-ray structure determination of the dppm derivative shows that it contains a metal core based on an Os₇ edge-bridged bicapped tetrahedron with the two ₃-Au atoms capping adjacent triangular Os₃ faces of the central tetrahedron. In an analogous reaction, the carbido anion [Os₇(H)C(CO)₁₉]^– affords the neutral cluster [Os₇C(CO)₁₉{Au₂(dppm)}] (7) when treated with [Au₂(dppm)]²⁺ in the presence of base.     

新颍Mo-Cu-Se簇合物{MoCu3Se3I}(PPh3)3O·0.5CH2Cl2的合成及晶体结构

新颍Mo-Cu-Se簇合物{MoCu₃Se₃I}(PPh₃)₃O·0.5CH₂Cl₂是由［Et₄N］₂MoSe₄、Cu(PPh₃)₂NO₃和KI在乙腈和二氯甲烷1∶1的混合溶剂中反应所得。晶体属单斜晶系，空间群P2_{1相似文献}