二硫代草酸根桥联的双核镍(Ⅱ)配合物研究

Three binuclear Nickel(Ⅱ) complexes were synthesized, bridged with dithiooxalate, Ni₂(Bpy)₃(Dto)₂(H₂O)₃(1), Ni₂(Phen)₃(Dto)₂(H₂O)₃(2) and Ni₂(Me₂Bpy)₃(Dto)₂(H₂O)₂ (3) (Bpy=2,2′-Bipyridine, Phen=1,10-phenanthroline, Me₂Bpy=4,4′-dimethyl-2,2′-bipyridine, Dto^2-=Dithiooxalate), and characterized by elemental analyses, IR, UV-Visible spectra, conductance. The variable temperature magnetic susceptibilities for the complexes were measured in the range of temperature between 1.5 K and 298 K. Experimental data of magnetic susceptibility were successfully fit to theoretical value based on the spin Hamiltonian operator：(?), S₁=S₂=1, giving the magnetic exchange parameters of 2J=-52.8 cm^-1. This result indicates the presence of a strong antiferromagnetic spin exchange interaction between the Ni(Ⅱ) ions. The magnetic exchange parameters of the binuclear Nickel(Ⅱ) complexes bridged with dithiooxalate is larger than that of the binuclear Nickel(Ⅱ) complexes bridged with oxalate. Dithiooxalate is more effective to transfer antiferromagnetic spin exchange interaction between the Ni(Ⅱ) ions than oxalate.     

N，N′-双(2-吡啶甲基)二硫代草酰胺根桥联的三核铜(Ⅱ)配合物的合成及表征

Two new trinuclear copper(Ⅱ) complexes bridged with N,N′-Bis(2-pyridylmethyl)-Dithiooxamidate, ［Cu₃L₂］(ClO₄)₂(1) and ［Cu₃L₂］(NO₃)₂(2) (H₂L=N,N′-Bis(2-pyridylmethyl)-Dithiooxamide), have been synthesized, and characterized by elemental analyses, IR, UV-visible spectra, conductance and EPR spectra. The variable temperature magnetic susceptibility for complex (1) has been measured in the range of 1.5～298K. Experimental data of magnetic susceptibility are successfully fit to theoretical value based on the spin Hamiltonian operator: H=-2J(S₁S₂+S₂S₃)-2J′S₁S₃, S₁=S₂=S₃=1/2, giving the magnetic exchange parameters of 2J=-170 cm^-1 and 2J′=-7.2 cm^-1. This result indicates the presence of a strong antiferromagnetic spin exchange interaction between the Cu(Ⅱ) ions.     

N，N′-双(2-吡啶乙基)二硫代草酰胺根桥联的三核铜(Ⅱ)配合物的合成及性质

Two Trinuclear copper(Ⅱ) complexes bridged with N,N′-Bis(2-pyridylethyl)-Dithiooxamidate, [Cu₃L₂](ClO₄)₂ (1) and [Cu₃L₂](NO₃)₂ (2) (H₂L=N,N′-Bis(2-pyridylethyl)-Dithiooxamide), have been synthesized, and characterized by elemental analyses, IR, UV-Visible spectra, conductance and EPR spectra. The variable temperature magnetic susceptibility for complex 1 has been measured in the temperature range of 1.5～298 K. Experimental data of magnetic susceptibility are successfully fit to theoretical value based on the spin Hamiltonian operator：(?), S₁=S₂=S₃=1/2, giving the magnetic exchange parameters of 2J=-221.6 cm^-1 and 2j=-15.8 cm^-1. This result indicates the presence of a strong antiferromagnetic spin exchange interaction between the Cu(Ⅱ) ions.     

自旋交叉配合物[Fe(ttd)2(NCS)2]·H2O的合成和磁性研究

The ligand ttd(ttd=1,4,8,9-Tetraaza-triphenylene-2,3-dicarbonitrile) and a novel spin crossover complex [Fe(ttd)₂(NCS)₂]·H₂O were synthesized, and characterized by elemental analysis, IR, MS, and UV-vis spec-troscopy. The temperature dependence of magnetic susceptibility shows that there are a little break between 150～190K and an unusual step transition with a 50K width between 190～240K. Compared with the other complexes with the resemble structure, it can be found that the influence of ligand is very notable.     

邻苯二甲酸单乙酯铜配合物的晶体结构与强反铁磁性

A hydrated tetra-carboxylato-bridged dinuclear copper(Ⅱ) complex [Cu₂(mEP)₂(H₂O)₂]₂ (1) (mEp is mono -ethyl phthalate or 1,2-benzenedicarboxylate monoethyl ester) has been prepared and characterized by X-ray diffraction single crystal structure analysis and magnetic measurements. This dinuclear complex adopts dimeric paddle-wheel cage structure and the coordination model around each copper(Ⅱ) atom is square-pyramidal with four oxygen atoms of the carboxylate groups from four different mono-ethyl phthalate ligands and one oxygen atom of water as apical position. The magnetic data for 1 exhibited strong intramolecular antiferromagnetic interaction between the two paramagnetic metal ions with 2J=-315.18 cm^-1. Comparing with other related complexes in structure and magnetic propertity, the main factor which determines the strong antiferromagnetic interaction in the dimeric copper(Ⅱ) carboxylates is the electronic structure of the bridging O-C-O moiety. CCDC: 624561.     

配位聚合物{[Co(4,4′-bpy)(H2O)4](Fum)·4H2O}n的合成和晶体结构

The complex {[Co(4,4′-bpy)(H₂O)₄](Fum)·4H₂O}_n(where 4,4′-bpy = 4,4′-bipyridine and Fum = fumarate) was synthesized and characterized by X-ray diffraction. The complex consists of one-dimensional chains containing cobalt(Ⅱ) ions bridged by 4,4′-bpy molecules. The six-coordination of Co²⁺ is achieved by means of four water molecules. The fumarate is not coordinated to cobalt ion while it forms hydrogen bonds with coordinated and non-coordinated water molecules and extends the structure into three-dimensional hydrogen bonding network. CCDC: 190488.     

异双桥二维镍(Ⅱ)配位聚合物 ∞2[Ni(μ-4，4′-bpy)2/2(μ-L)4/2](HL=2-indolyl-formic acid)的水热合成和晶体结构

The allo-bisbridge 2D coordination polymer _∞²[Ni(μ-4，4′-bpy)_2/2(μ-L)_4/2](HL=2-indolyl-formic acid) has been obtained by using hydrothermal synthesis, and the results of X-ray single crystal diffraction analysis show that the compound crystallizes in monoclinic system, space group C2/c (No.15) with a=2.300 2(5) nm, b=1.129 1(2) nm, c=0.974 0(2) nm, β=109.85(3)°, V=2.379 2(8) nm³, D_c=1.494 g·cm^-3, Z=4, F(000)=1 104, μ=0.860 mm^-1, R=0.032 2, wR=0.088 8. The crystal structure consists of the [Ni(μ-4,4′-bpy)_2/2(μ-L)_4/2] complex molecules, in which the Ni atom is octahedrally coordinated by two N atoms from two different 4,4′-bpy molecule ligands and four O atoms from four different L- anion ligands. TG analysis indicate that title coordination polymer possesses relatively high thermal stability. CCDC: 252833.     

Nin(n=3～39)团簇结构，能量和稳定性的研究

The stable geometric structure and energy of Ni_n(n=3～39) clusters as a function of cluster size are studied by the Monte Carlo simulation. The interaction among atoms is calculated through Lennard-Jones plus Axilrod-Teller potentials. It is found that the clusters grow through adding atoms on one or more surfaces of Ni₇ or Ni₁₃ after the cluster size n is larger than 7. It is also found that there exists direct correlation between the stability and geometrical structures of clusters. Relatively, highly symmetry clusters are more stable. In addition, the nickel clusters with fcc-like structure such as Ni₃₃, Ni₃₆ and Ni₃₈ are more stable than their neighboring clusters.     

以氯醌酸二价阴离子为桥联配体的Fe(Ⅲ)-Fe(Ⅲ)和Mn(Ⅱ)-Mn(Ⅱ)双核配合物的合成与磁性

Two new binuclear Fe(Ⅲ)-Fe(Ⅲ) and Mn(Ⅱ)-Mn(Ⅱ) complexes containing the dianions of chloranilic acids (CA) which act as bridging ligand in the complexes, have been synthesized namely [Fe₂(phen)₄(u-CA)](ClO₄)₄·2H₂O and [Mn₂(phen)₄(u-CA)](ClO₄)₂·3H₂O (phen = O-phenanthroline; CA = dianions of chloranilic acids). They have been characterized by elemental analyses, IR, electronic spectra, susceptibility and variable-temperature magnetic susceptibility. The results indicate that there is a antiferromagnetic interaction between metal ions in the complexes at low temperature. The observed data were well fitted to those from a Heisenberg model. The obtained parameters: J= -2.02cm^-1, g = 2.25 for Fe(Ⅲ)-Fe(Ⅲ) complex; J=-5.45cm^-1, g = 2.01 for Mn(Ⅱ)-Mn(Ⅱ) complex.     

Cyano-bridged Ln^3＋-Cr^3＋ Binuclear Complexes [Ln（L）x（H2O）y^- Cr（CN）6]·mL·nH2O （Ln=La-Nd,x=5, y=2, m=1 or 2, n=2 or 2.5; Ln-Sm-Dy,Er, x=4, y=3, m=0, n=1.5 or 2.0; L= 2-pyrrolidinone）： Structure,Magnetism and Spin Density Map

In order to shed light upon the nature and mechanism of 4f-3d magnetic exchange interactions, a series of binuclear complexes of lanthanide（3＋） and chromium（3＋） with the general formula [Ln（L）5（H2O）2Cr（CN）6]·mL· nH2O （Ln=La （1）, Ce （2）, Pr （3）, Nd （4）; x=5, y=2, m=1 or 2, n=2 or 2.5; L=2-pyrrolidinone） and [Ln（L）4（H2O）3Cr（CN）6] ·nH2O （Ln=Sm （5）, Eu （6）, Gd （7）, Tb （8）, Dy （9）, Er （10）; x=4, y=3, m=0, n= 1.5 or 2.0; L=2-pyrrolidinone） were prepared and the X-ray crystal structures of complexes 2, 6 and 7 were determined. All the compounds consist of a Ln-CN-Cr unit, in which Ln^3＋ in a square antiprism environment is bridged to an octahedral coordinated Cr^3＋ ion through a cyano group. The magnetic properties of the complexes 3 and 6-10 show an overall antiferromagnetic behavior. The fitting to the experimental magnetic susceptibilities of 7 give g= 1.98, J=0.40 cm^-1, zJ＇= -0.21 cm^-1 on the basis of a binuclear spin system （Scd=7/2, Scr=3/2）, revealing an intra-molecular Gd^3＋-Cr^3＋ ferromagnetic interaction and an inter-molecular antiferromagnetic interaction. For 7 the calculation of quantum chemical density functional theory （DFT）, combined with the broken symmetry approach, showed that the calculated spin coupling constant was 20.3 cm^-1, supporting the observation of weak ferromagnetic intra-molecular interaction in 7. The spin density distributions of 7 in both the high spin ground state and the broken symmetry state were obtained, and the spin coupling mechanism between Gd^3＋ and Cr^3＋ was discussed.     

Density profile of spin cast polymethylmethacrylate thin films

The density profiles of polymethylmethacrylate (PMMA) thin films on silicon (111) single crystal wafers were investigated via neutron reflectivity measurements. Films were prepared by spin casting PMMA onto silicon wafers from o-xylene solution followed by annealing under vacuum at 90°C for 5 h. A ～45 Å thick layer at the free polymer surface was observed in the as-prepared samples that has a density about half the value of bulk PMMA. After heating above 110°C, this diffuse layer disappeared and the thin film density profile was transformed to one with a sharp free polymer surface. This transition was found to be irreversible. © 1994 John Wiley & Sons, Inc.     

A Generalized Unpaired Electron Spin Density Equation and Organic Hyperconjugation Mechanism

A large class of stereochemcial and related interactions in organic chemistry are repulsive and others are attractive, but the relative orientation of two methyl groups and the amount of energy required to twist one relative to the other (the hindered rotation energy barriers), or the alignment of such a group with respect to a conjugated ring to which it is attached (widely attributed to a mechanism called “hyperconjugation”) are estimated to be small in compared with the total energy of the molecule. We used theories of both isotropic and anisotropic proton hyperfine interactions in the π‐electron systems developed in the early sixties. They are approximated by the magnetic dipole nteractions between each proton and an electron spin magnetization that is distributed in 2s and 2p Slater atomic orbitals center on carbon atoms. We have extended these theories to the non‐planar olefinic cation radicals, which are very important in biochemistry as well as in petroleum catalysis. A three dimensional electron spin density equation has been developed in this paper to handle some Jahn‐Teller vibronic molecules. The new electron spin density equation related the observed proton hyperfine splittings to the non‐planar structures of the open‐chain alkene cation radicals generated by radiolysis and various chemical oxidation methods. The spin densities and the conformational calculations based on valence bond theory and symmetry principles are compared with some more elaborated molecular orbital calculations in the literature. The localized valence bond approaches are better in accord with our experimental results. The anomalous line‐width effect of the four methyl groups observed in the 2,3‐dimethyl‐2‐butene cation radicals also confirmed the positive sign of the electron‐proton hyperfine constant of hyper‐conjugation mechanism. A methyl substituent attached to a conjugated molecule often behaves as if it formed part of the region of conjugation; the charge appears to flow from the methyl group into the π electron system and it may also give rise to an appreciable dipole moment. Methylation also gives rise to an appreciable dipole moment, and the resultant red shift of electronic absorption bands is of some importance in the design of dye molecules.     

Prediction of Spin Density,Baird-Antiaromaticity,and Singlet–Triplet Energy Gap in Triplet-State Polybenzenoid Systems from Simple Structural Motifs

Triplet-state aromaticity has been recently proposed as a strategy for designing functional organic electronic compounds, many of which are polycyclic aromatic systems. However, in many cases, the aromatic nature of the triplet state cannot be easily predicted. Moreover, it is often unclear how specific structural manipulations affect the electronic properties of the excited-state compounds. Herein, the relationship between the structure of polybenzenoid hydrocarbons (PBHs) and their spin-density distribution and aromatic character in the first triplet excited state is studied. Although a direct link is not immediately visible, classifying the PBHs according to their annulation sequence reveals regularities. Based on these, a set of guidelines is defined to qualitatively predict the location of spin and paratropicity and the singlet–triplet energy gap in larger PBHs, using only their smaller tri- and tetracyclic components, and subsequently tested on larger systems.     

Density functional and multiconfigurational ab initio study of the ground and excited states of Os2

Multiconfigurational ab initio methods predict that the ⁵Π_u state as the ground state instead of the ⁷Δ_u state. Although multiconfigurational perturbation theory correctly predicts the ground state, they overestimate the bond dissociation energy (BDE). Only multireference configuration interaction method can reasonably calculate the BDE. The spin‐orbit effect on the spectroscopic constants is not significant. The results calculated by density functional theory (DFT) vary significantly depending on the selection of a DFT functional. No DFT functional gives the same energy ordering as calculated by the second‐order multiconfigurational perturbation theory (CASPT2). The old generalized gradient approximations functionals are well suited for predicting the ground state and calculating the bond length and the vibrational frequency of Os₂. According to the CASPT2 calculation, the ground state of Os₂ has a quadruple bond. © 2014 Wiley Periodicals, Inc.     

Density matrices from position and momentum densities

Summary One-electron density matrices, which are representable in single-centers-orbital basis sets, have been investigated with respect to their reconstruction from densities. The maximum allowed dimension for reconstruction from a combination of position & momentum density dependent properties is only slightly bigger than the dimension in the case of position (or momentum) densities only. Since for a given one-particle basis of dimensionM, the number of one-matrix elements which can be determined is also of orderM only, while the total number of one-matrix elements is of orderM ², it is in general necessary to introduce severe constraints and restrictions. The accuracy demands on the data and algorithms increase exponentially for linearly increasing size of basis set.     

Density functionals in the presence of magnetic field

In this article, density functionals for Coulomb systems subjected to electric and magnetic fields are developed. The density functionals depend on the particle density ρ and paramagnetic current density j^p. This approach is motivated by an adapted version of the Vignale and Rasolt formulation of current density functional theory, which establishes a one‐to‐one correspondence between the nondegenerate ground‐state and the particle and paramagnetic current density. Definition of N‐representable density pairs (ρ,j^p) is given and it is proven that the set of v‐representable densities constitutes a proper subset of the set of N‐representable densities. For a Levy–Lieb‐type functional Q(ρ,j^p), it is demonstrated that (i) it is a proper extension of the universal Hohenberg–Kohn functional to N‐representable densities, (ii) there exists a wavefunction ψ₀ such that , where H₀ is the Hamiltonian without external potential terms, and (iii) it is not convex. Furthermore, a convex and universal functional F(ρ,j^p) is studied and proven to be equal the convex envelope of Q(ρ,j^p). For both Q and F, we give upper and lower bounds. © 2014 Wiley Periodicals, Inc.     

DMA4500数字式密度仪测定精油密度不确定度评定

目的：对使用DMA4500数字式密度仪测定精油密度的不确定度进行评定,确定影响不确定度的关键因素,判定该仪器是否满足标准要求。方法依据JJF 1059-2012对使用DMA4500数字式密度仪测定精油密度结果的不确定度进行评定,分析影响测量不确定度的各个因素,对各个分量进行计算和合成。结果该实验的不确定度主要来自重复性测量和仪器本身的准确性;其扩展不确定度U＝6×10-5 g/cm3,置信概率95％。结论用DMA4500数字式密度仪测定精油密度能较好地满足标准要求。