氢原子在Ni(100), Ni(111)和Ni(110)面上吸附扩散势能面的结构

本文构造了氢-镍相互作用的5参数Morse势, 用经典的对势方法研究氢原子在Ni(100), Ni(111)和Ni(110)面上的吸附和扩散, 得到氢原子在三个表面上的吸附位、吸附几何、结合能及本征振动等数据, 和实验结果符合得很好。同时, 系统地研究了三个体系的吸附扩散势能面结构。     

Mononuclear and Binuclear Fe(III), Co(II), Ni(II), and Cu(II) Complexes of 3,4′-Dihydroxyazobenzene-3′,4-dicarboxylic Acid and 3-Carboxy-4-hydroxyphenylazo-3-carboxy-4-hydroxynaphthalene

Fe(III), Co(II), Ni(II), and Cu(II) complexes of the title azodyes have been synthesized and characterized by elemental analysis, molar conductance, TGA, DTA, magnetic susceptibility measurements, IR, electronic and ESR spectral studies. The spectral studies suggest an octahedral geometry for Fe(III) and Co(II) complexes but a square planar geometry for Ni(II) and Cu(II) complexes. The kinetics of the catalysed oxidation of N,N,N,N-tetramethyl-p-phenylenediamine dihydrochloride (TMPPD) with mononuclear and binuclear copper complexes were studied to check the activity of these copper complexes in oxidizing organic amines. The electrochemical behaviour of the metal complexes was studied using DC polarography and cyclic voltammetry. Antimicrobial activity of the azo compounds and its complexes have been tested against different microorganisms.     

Mononuclear and Binuclear Fe(III), Co(II), Ni(II), and Cu(II) Complexes of 3,4′-Dihydroxyazobenzene-3′,4-dicarboxylic Acid and 3-Carboxy-4-hydroxyphenylazo-3-carboxy-4-hydroxynaphthalene

Summary. Fe(III), Co(II), Ni(II), and Cu(II) complexes of the title azodyes have been synthesized and characterized by elemental analysis, molar conductance, TGA, DTA, magnetic susceptibility measurements, IR, electronic and ESR spectral studies. The spectral studies suggest an octahedral geometry for Fe(III) and Co(II) complexes but a square planar geometry for Ni(II) and Cu(II) complexes. The kinetics of the catalysed oxidation of N,N,N,N-tetramethyl-p-phenylenediamine dihydrochloride (TMPPD) with mononuclear and binuclear copper complexes were studied to check the activity of these copper complexes in oxidizing organic amines. The electrochemical behaviour of the metal complexes was studied using DC polarography and cyclic voltammetry. Antimicrobial activity of the azo compounds and its complexes have been tested against different microorganisms.     

Influence of axial ligands and anions on the Ni–Ni distances in trinickel string complexes: synthesis,structure, and properties of [Ni3(dpa)4(CH3CN)2] · (ClO4)2 · (CH3CN) · H2O

A cation–anion metal string complex with neutral axial ligands, [Ni₃(dpa)₄(CH₃CN)₂] · (ClO₄)₂ · (CH₃CN) · H₂O (1) where dpa^? is 2,2′-dipyridylamine anion, was synthesized and characterized by elemental analysis, IR, fluorescence, UV, and CV spectroscopic methods, and single crystal X-ray analysis. The Ni–Ni distances in 1 are longer than those in [Ni₃(dpa)₄(CH₃CN)₂] · (PF₆)₂ · 3.14CH₃CN (2) and [Ni₃(dpa)₄F₂] · [Ni₃(dpa)₄(H₂O)₂] · (BF₄)₂ · 2CH₃OH, indicating that the counter anions affect the Ni–Ni distances of trinickel string complexes. Compared with Ni₃(dpa)₄Cl₂ and Ni₃(dpa)₄(ClO₄)₂, 1 also has different fluorescence, UV, and CV properties. Therefore, this study clearly indicates that ligands and counter anions largely influence the structures and properties of trinickel string complexes.     

Osmotic and Activity Coefficients of CH3SO4Na(aq) and CH3SO4K(aq) at 25°C

The osmotic and activity coefficients of aqueous sodium and potassium methyl sulfates have been determined at 25°C by the isopiestic method, in the molality range from ca.0.2 to 25 and 19 mol-kg^–1, respectively. The results have been discussed in terms of the ion–ion and ion–water interactions on the basis of the Pitzer and Mayorga model and a method developed in our laboratory.     

Synthesis and Structure of Acetonitrile Solvates of Copper(II) Monofluoroacetate and Silver(I) Trifluoroacetate, [Cu2(CH2FCOO)4· 2CH3CN](CH3CN) and Ag3(CF3COO)3(CH3CN)2

Compounds [Cu₂(CH₂FCOO)₄· 2CH₃CN](CH₃CN) (I) and Ag₃(CF₃COO)₃(CH₃CN)₂(II) were synthesized and studied by X-ray structural analysis. Crystals Iare monoclinic, space group C2/c, a= 27.854(6), b= 8.286(2), c= 19.428(4) Å, = 106.82(3)°, V= 4292(2) ų, Z= 8, R ₁= 0.0426; crystals IIare triclinic, space group , a= 8.676(2), b= 9.819(2), c= 11.961(2) Å, = 95.27(3), = 109.59(3)°, = 104.60(3)°, V= 911.4(3) ų, Z= 2, R ₁= 0.0252. Structure Iis composed of the structural units (lanterns) typical of copper(II) carboxylates. The presence of an additional acetonitrile molecule noncoordinated by the copper atoms makes it possible to consider compound Ias a lattice clathrate. Structure IIhas no analogs among the silver carboxylates. It simultaneously contains silver atoms with coordination numbers varying from 2 to 4.     

Syntheses and structural characterizations of a new benzyl(4-methoxyphenyl)dithiophosphinic acid and its Ni(II), Co(II), Zn(II), Cd(II), and Ni–pyridine complexes

Benzyl(4-methoxyphenyl)dithiophosphinic acid (HL) was obtained as solid and was treated with the NiCl₂6H₂O, CoCl₂6H₂O, ZnCl_2, and CdCl₂ to prepare its Ni(II), Co(II), Zn(II), and Cd(II) complexes. The nickel complex was further treated with pyridine which led to the formation of octahedral dipyridine derivative. HL was obtained through the addition reaction of the perthiophosphonic acid anhydride Lawesson reagent, (LR), [2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide], with the corresponding Grignard compound (benzylmagnesium bromide) in diethyl ether medium.

The complexes were all of the stoichiometry of [M(L)₂]_x, with x = 1 for M = Ni²⁺ and x = 2 for M = Co²⁺, Cd²⁺ and Zn²⁺. The coordination geometry was square planar in the nickel(II) complex and tetrahedral in the others. Similar to many other nickel(II) complexes, the Ni(L)₂ reacts reversibly with pyridine to yield the octahedral complex ({(Py)₂Ni(L)₂}).

The compounds were characterized by elemental analysis; MS, FTIR, and Raman spectroscopies. The magnetic susceptibilities of the complexes were measured to confirm the hybridization patterns and the geometries. Single-crystal X-ray analyses of Ni(L)₂ and [Co(L)₂]₂ complexes were also carried out to prove the molecular topologies.     

Sb在Pt(100),Pt(110),Pt(111)及Pt(320)上不可逆吸附的电化学特性

研究了Sb在Pt(1 0 0 ) ,Pt(1 1 0 ) ,Pt(1 1 1 )和Pt(32 0 )单晶面上不可逆吸附的电化学特性 .发现当扫描电位的上限Eu≤ 0 .45V时 ,Sbad可以稳定地吸附在Pt(1 0 0 ) ,Pt(1 1 0 )和Pt(1 1 1 )表面 ,而Sbad在Pt(32 0 )表面稳定的电位较低 ,为Eu≤ 0 .40V .从饱和吸附Sb的铂单晶电极出发 ,通过改变电位扫描上限Eu 和电位扫描圈数可以获得不同Sb覆盖度 (θSb)的电极 .根据Sb和H在铂单晶电极表面共吸附的定量数据 ,对Sb在不同铂单晶面上饱和吸附的模型进行了初步探讨 .     

Electrical double layer on (111) and (100) faces of silver single crystals in solutions containing ClO4− and F−

The differential capacitance-potential dependence C(E) of electrolytically grown (111) and (100) faces of silver single crystals in diluted solutions of NaClO₄ and KF was studied. Comparison with results obtained in KF solutions shows a concentration-independent shift of E_min to more negative potentials and higher values of the reciprocal slope of the C⁻¹ vs. C_d⁻¹ plots. The data obtained have been explained as due to a weak specific adsorption of ClO₄⁻ which is stronger on the (100) face. The influence of water in the double layer on the adsorption has been discussed.     

噻吩在Ni(100),Cu(100),Co(100)表面吸附的密度泛函研究

采用密度泛函理论对噻吩分子在Ni(100),Cu(100)和Co(100)表面的吸附构型进行了GGA/PBE水平上的计算,通过比较吸附能及各结构参数,预测了各金属的脱硫活性.结果表明:噻吩在Ni表面发生了作用力较强的化学吸附,噻吩的S—C键有解离趋势;在Cu表面发生的是作用力较弱的物理吸附,噻吩分子构型并未发生较大变化;而噻吩在Co表面的吸附作用最强,噻吩的S—C键已经发生解离,和Co原子之间的距离已经达到甚至短于Co—S键的键长.这说明,金属的吸附脱硫活性为CoNiCu,与实验研究结果一致.此3种金属最稳定的分子吸附位均为hol45位.     

Synthesis, crystal structure, magnetic property and thermal studies of [Ni(CH(3)COO)2·(NH2CH2Ph)4

[Ni(CH(3)COO)(2)·(NH(2)CH(2)Ph)(4)] complex was synthesized using benzylamine and nickel acetate. The molecular structure of this complex was obtained by single crystal X-ray diffraction and characterized by elemental analysis, IR spectrometry and thermal analysis. The complex crystallized in the monoclinic space group P2(1)/n with cell parameters a=11.234(4)?, b=6.459(2)?, c=22.647(8)?, α=90.00, β=91.149(4)°, γ=90.00, V=1642.8(10)?(3), Z=2. The structure has been solved by direct methods and refined to R(1)=0.0876 for 6377 observed reflections I>2σ(I). Magnetic studies for complex show the data over the whole temperature range 5-300 K are well fitted to the Curie-Weiss law with C=1.03 cm(3) K mol(-1) and θ=-1.38 K. This fitting indicates antiferromagnetic interaction between the Ni ions and the metal center exhibits distorted octahedral coordination geometries. The thermal analysis was carried out to understand the thermal stability of the title complex.     

Structure and properties of Ni(110) surface coadsorbing chlorine and oxygen

The coadsorption of chlorine with oxygen on Ni(110) surface has been investigated by XPS, UPS, AES and work function measurements. The chlorine preadsorption drastically inhibits the further uptake of oxygen. On the contrary, precovered oxygen has hardly any influence on the additional adsorption of chlorine due to the incorporation of precovered oxygen into the subsurface driven by the chlorine coadsorption. ARXPS measurements provide the evidence for this coadsorption model. The thermal desorption of chlorine and oxygen from the coadsorption surface is very similar to that of both individual adsorbates under the same heating conditions, but the desorption temperature of both the adsorbates apparently decreases on the coadsorption surface. The coadsorption and thermodesorption mechanisms are also discussed in detail.     

Temperature dependent absorption spectra of Br(-), Br2(•-), and Br3(-) in aqueous solutions

The absorption spectra of Br(2)(?-) and Br(3)(-) in aqueous solutions are investigated by pulse radiolysis techniques from room temperature to 380 and 350 °C, respectively. Br(2)(?-) can be observed even in supercritical conditions, showing that this species could be used as a probe in pulse radiolysis at high temperature and even under supercritical conditions. The weak temperature effect on the absorption spectra of Br(2)(?-) and Br(3)(-) is because, in these two systems, the transition occurs between two valence states; for example, for Br(2)(-) we have (2)Σ(u) → (2)Σ(g) transition. These valence transitions involve no diffuse final state. However, the absorption band of Br(-) undergoes an important red shift to longer wavelengths. We performed classical dynamics of hydrated Br(-) system at 20 and 300 °C under pressure of 25 MPa. The radial distribution functions (rdf's) show that the strong temperature increase (from 20 to 300 °C) does not change the radius of the solvent first shell. On the other hand, it shifts dramatically (by 1 ?) the second maximum of the Br-O rdf and introduces much disorder. This shows that the first water shell is strongly bound to the anion whatever the temperature. The first two water shells form a cavity of a roughly spherical shape around the anion. By TDDFT method, we calculated the absorption spectra of hydrated Br(-) at two temperatures and we compared the results with the experimental data.     

A Density Functional Theory Study on the Adsorption of CN on Ni(111) Surface

1 INTRODUCTION Cyanide, CN, is an important free-radical mole-cule of one carbon chemistry, organic chemistry, free-radical chemistry and cosmochemistry. And the im-portant industrial processes, such as the Andrussovreaction, depend on the reactivity of CN bond[1]. Thechemistry of cyanide is also important in the surfacechemistry of a number of C- and N-containing sys-tems[1, . During the past decade, the adsorption of 2]CN and CN-containing molecules on transition metalsurfa…     

Magnetic and spectral properties of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Pd(II) chelates of 2′-hydroxy-3′-bromo-4-methoxy-5′-methylchalkone oxime (HBMMCO)

A number of chelates of the transition metal ions Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺ and Pd²⁺ with 2′-hydroxy - 3′ - bromo - 4 - methoxy - 5′ - methylchalkone oxime (HBMMCO) have been synthesised. Attempts have been made to assign their probable structures on the basis of elemental analysis, molar conductance, thermal analysis, absorption and reflectance spectra, IR spectra and magnetic data. The magnetic susceptibility of the Co(II) chelate follows the Curie-Weiss law and the observed temperature dependance is in favour of an octahedral configuration. The Ni(II) chelate exhibits a 6-coordinate octahedral structure, whilst distorted octahedral geometry is suggested for the Cu(II) chelate. The Fe(II) and Fe(III) chelates have high spin octahedral configurations and the dimagnetic behaviour of the Pd(II) complex indicates a square planer configuration.     

Theoretical calculations of CH4 and H2 associative desorption from Ni(111): could subsurface hydrogen play an important role?

The results of theoretical calculations of associative desorption of CH(4) and H(2) from the Ni(111) surface are presented. Both minimum-energy paths and classical dynamics trajectories were generated using density-functional theory to estimate the energy and atomic forces. In particular, the recombination of a subsurface H atom with adsorbed CH(3) (methyl) or H at the surface was studied. The calculations do not show any evidence for enhanced CH(4) formation as the H atom emerges from the subsurface site. In fact, there is no minimum-energy path for such a concerted process on the energy surface. Dynamical trajectories started at the transition state for the H-atom hop from subsurface to surface site also did not lead to direct formation of a methane molecule but rather led to the formation of a thermally excited H atom and CH(3) group bound to the surface. The formation (as well as rupture) of the H-H and C-H bonds only occurs on the exposed side of a surface Ni atom. The transition states are quite similar for the two molecules, except that in the case of the C-H bond, the underlying Ni atom rises out of the surface plane by 0.25 A. Classical dynamics trajectories started at the transition state for desorption of CH(4) show that 15% of the barrier energy, 0.8 eV, is taken up by Ni atom vibrations, while about 60% goes into translation and 20% into vibration of a desorbing CH(4) molecule. The most important vibrational modes, accounting for 90% of the vibrational energy, are the four high-frequency CH(4) stretches. By time reversibility of the classical trajectories, this means that translational energy is most effective for dissociative adsorption at low-energy characteristic of thermal excitations but energy in stretching modes is also important. Quantum-mechanical tunneling in CH(4) dissociative adsorption and associative desorption is estimated to be important below 200 K and is, therefore, not expected to play an important role under typical conditions. An unexpected mechanism for the rotation of the adsorbed methyl group was discovered and illustrated a strong three-center C-H-Ni contribution to the methyl-surface bonding.     

Properties and structure of new volatile phenyl-containing β-diketonates of trimethylplatinum(IV): (CH3)3Pt(btfa)H2O, (CH3)3Pt(bac)Py, and initial complex [(CH3)3PtI]4

By interaction of trimethylplatinum(IV) iodide with phenyl-containing β-diketonates, the volatile monomeric complexes of trimethylplatinum(IV) based on benzoyltrifluoroacetone (Hbtfa) and benzoylacetone (Hbac) of the composition (CH₃)₃Pt(btfa)H₂O (I) and (CH₃)₃Pt(bac)Py (II) are obtained. Synthesis of the complexes is described; data of elemental analysis and IR spectra are reported; thermal characteristics are studied by thermogravimetry. For the first time, a single crystal X-ray diffraction study of complexes (I), (II), and the initial tetrameric complex [(CH₃)₃PtI]₄ (III) is performed.     

CoMFA 3D-QSAR Analysis of Epothilones Based on Docking Conformation and Alignment

Epothilones belong to a class of novel microtubule stabilizing and anti-mitotic agents, which have a paclitaxel-like mechanism of action. A three-dimensional quantitative structure-activity relationship （3D-QSAR） model was built for epothilones by the method of comparative molecular field analysis （CoMFA） combined with the flexible docking technology. The docking CoMFA model gave a good cross-validated value of q2=0.784 with an optimized component of 6 and the conventional correlation coefficient of r^2=0.985. The statistical results show that the model has good ability to predict the activity of the studied compounds. At last, the docking CoMFA model was analyzed through contour maps complemented with MOLCAD-generated active site potential surface in the α,β-tubulin receptor, which can provide important information for the structure-based drug design.     

Four Complexes of Mn(Ⅱ), Co(Ⅱ), Ni(Ⅱ) and Cu(Ⅱ) Based on 2-Morpholine-4-yl-4,6-di-pyrazol-1-yl-1,3,5-triazine

Three azide bridged complexes, namely, [Mn_2L_2(N_3)_4(H_2O)_2](1), [Co_2L_2(N_3)_4]·(H_2O)_3(2) and [Ni_2L_2(N_3)_3(H_2O)]N_3·(H_2O)_4(3)(L = 2-morpholine-4-yl-4,6-di-pyrazol-1-yl-1,3,5-triazine), were synthesized by the reaction of L ligand, sodium azide with Mn(Ⅱ), Co(Ⅱ) and Ni(Ⅱ) chlorides. The copper(Ⅱ) chloride combined with thiocyanate and L ligand to form a mononuclear complex [CuL(CH_3OH)(SCN)(NCS)](4). Complexes 1~4 were characterized by IR, elemental analysis and X-ray crystallographic analysis. It was worth noting that two Mn(Ⅱ) atoms were connected by the end-to-end mode in 1, while Co(Ⅱ) and Ni(Ⅱ) atoms were connected by the end-on mode in 2 and 3. In complex 4, the central copper atom was coordinated with a sulfur atom and a nitrogen atom of the two thiocyanate ligands, respectively. Hydrogen bonds, π-π stacking interactions, thermogravimetric analysis and fluorescence properties of 1~4 were studied.     

Model studies of the chemisorption of hydrogen and oxygen on the Au (1 0 0) surface

 The convergence of chemisorption energy for hydrogen and oxygen on gold clusters is studied. Two theoretical approaches have been employed; wavefunction methods at the self-consistent-field second–order M?ller–Plesset level and density functional theory and the two methods are compared. Relativistic effective core potentials exploited in the former approach were developed in this work. Received: 25 October 1999 / Accepted: 21 February 2001 / Published online: 11 October 2001