新显色剂对溴苯基重氮氨基偶氮苯与镍显色反应的研究及应用

本文研究了新显色剂对溴苯基重氮氨基偶氮苯与镍的显色反应。在非离子表面活性剂ＯＰ存在下，于ｐＨ９．６的硼砂－氢氧化钠介质中，镍与该试剂形成１：３稳定的红色配合物，其最大吸收波长位于５４０ｎｍ处，表现摩尔吸光系数ε＝９．０×１０４Ｌ·ｍｏｌ－１·ｃｍ－１，镍量在０－１１μｇ／２５ｍＬ范围内符合比尔定律。用于铝合金中微量镍的测定，结果满意。     

Micelle formation in sodium hexadecyl sulfate surfactant solutions studied by small-angle neutron scattering

Micelle formation in aqueous sodium hexadecyl sulfate solutions is studied by small-angle neutron scattering. Measurements are carried out at different concentrations (1.1, 2.2, 3.2, 5.4, 10.9 and 32.8 mM/dm³) and at different temperatures (40°, 50°, and 60°C). The monotonous evolution of interparticle correlation can be observed on the measured scattering patterns. At high concentrations (10.9 and 32.8 mM/dm³) scattering patterns are described by interacting ellipsoids, but at low concentrations by non-interacting ellipsoids. Computation of the distance distribution function proved the ellipsoidal shape at 10.9 and 32.8 mM/dm³, but showed an unexpectedly large particle dimension and elongation of the micelles at lower concentrations.     

Ligand-stabilized Nickel and Palladium Boride Colloids

A route to the first ligand stabilized nickel and palladium boride colloids with core diameters of 1.4 and 1.6 nm is described. The particles are formed by reaction of the metal complexes Cl₂M(PR₃)₂ (M = Ni, Pd, PR₃ = PPr₃, PBu₃) with B₂H₆ in toluene at room temperature with 40–70% yield. The characterization of the pyrophoric brown powders occurred by elementary analyses, resulting in smallest formula units, which then could be extended to averaged molecular formulas by mass determinations, using an analytical ultracentrifuge: [Ni₆B₁₀Cl_1.5(PPr₃)]_12.5 ( 1 ), [Ni₆B₁₀Cl_1.5(PBu₃)]_8.5 ( 2 ), [Pd₄B₆Cl(PPr₃)]_16.5 ( 3 ), and [Pd₄B₆Cl(PBu₃)]_16.5 ( 4 ). From the masses of the colloid cores and their roughly calculated densities the size of the boride particles could be estimated. The diameters of 1.6 nm for 1, 3 , and 4 are identical within the experimental error. Only 2 seems to have a slightly reduced diameter of 1.4 nm. 1–4 can be dispersed in inert organic solvents in any concentration. To confirm these relatively uncertain values high resolution transmission electron microscopy has been used. Investigations of 1 and 3 show indeed an averaged particle size of 1.6 ± 0.3 nm in agreement with the data derived from the mass determinations. Surprisingly most of the observed particles appear to have amorphous structure. This finding is supported by X-ray powder diffraction experiments, as no significant reflex data could be registered. ³¹P and ¹¹B NMR measurements have been performed too, however, do not contribute to further characterization.     

Nickel(II)‐Komplexe von Oxalamidinen und Oxalamidinaten mit zusätzlichen R2P‐Donorgruppen

Complexes of Nickel(II) with Oxalic Amidines and Oxalic Amidinates with Additonal R₂P‐Donor Groups Oxalamidines R¹N=C(NHR²)‐C(=NHR²)=NR¹, which bear additional donor atoms at two of the four N substituents ( H₂A : R¹ = mesityl, R² = ‐(CH₂)₃‐PPh_2; H₂B : R¹ = tolyl, R² = ‐(CH₂)₃‐PMe₂) form binuclear complexes with Nickel(II) in which very different coordination modes are realized. In the complex [ (A) Ni₂Br₂] (1) the two nickel atoms at each side of the bridge are in a square‐planar environment, coordinated by the two N donor atoms of the oxalic amidinate framework, a bromide and a Ph₂P group. An analogous coordination has the organometallic compound [ (A) Ni₂Me₂] (2) . In contrast, the two nickel atoms in the compound {[( B )][Ni(acac)]₂} (5) differ in their coordinative environment. At one side of the oxalic amidinate bridging ligand a (acac)Ni fragment is coordinated by the two N donor atoms resulting in a square‐planar environment. At the opposite side the (acac)Ni fragment is coordinated at the both N donor ligands of the bridging ligand as well as at the two PMe₂ groups of the side chains resulting in an octahedral coordination for this nickel atom.     

BF_3·OEt_2在镍体系催化丁二烯聚合中的作用

本文借助于紫外可见光谱、磁化率法和聚合活性测定等方法,研究了BF_3·OEt_2在镍体系催化丁二烯聚合中的作用。初步探明了BF_3·OEt_2与Ni(naph)_2作用会形成“F-B-Ni”配合物,对形成活性中心不利。     

Ein neues Oxochromat: SrNi2Cr8O15 vom Strukturtyp BaV10O15

Summary A new quaternary oxochromate(III) was prepared by solid state reaction. Single crystal X-ray investigations of SrNi₂Cr₈O₁₅ show that this compound belongs to the BaV₁₀O₁₅ type. [Space group D _2h ¹⁸ - Ccmb,a=10.042;b=11.413;c=9.260 Å;Z=4.] Ni²⁺ and Cr³⁺ occupy the octahedrally coordinated point positions statistically. The surrounding of Sr²⁺ is similar to the iso- and heteropolyacids.

     

The self-assembly of metallic nanowires

We have demonstrated that nickel adatoms self-assemble into quasi one-dimensional nanowires on vicinal Rh(1 1 1) surfaces by decorating their regular monoatomic step arrays, while V adatoms do not. The step decoration process has been followed experimentally by variable-temperature scanning tunnelling microscopy and high-resolution X-ray photoelectron spectroscopy. The physical origin of the different step-assisted self-assembly behaviour of Ni and V adatoms has been elucidated theoretically and is ascribed to different diffusion barriers and trapping capability of Ni and V at Rh steps.     

Adsorption of SH and OH and coadsorption of S, O and H on Ni(111)

The adsorption of SH and OH radicals on Ni(111) is treated using an ab initio embedding theory. The Ni(111) surface is modeled as a three-layer, 28-atom cluster with the Ni atoms fixed at bulk lattice sites. The Ni(111) energy surface is very flat for SH adsorption if the H tilt angle is allowed to vary. At both atop and bridge sites, the S---H axis is tilted away from the surface normal by 70°, resulting in the sulfur atom being sp³-hybridized and the adsorption energy being 59 kcal mol⁻¹. For SH at the three-fold site, the S---H axis is normal to the surface, the sulfur is sp-hybridized, and the adsorption energy is 58 kcal mol⁻¹. OH is preferentially adsorbed at the three-fold site. The calculated adsorption energy is 90 kcal mol⁻¹ and the O---H axis is perpendicular to the surface. OH adsorption at the atop and bridge sites is 16 and 5 kcal mol⁻¹ less stable than at the three-fold site, respectively. Atomic H, O and S are preferentially adsorbed at the three-fold site. The calculated adsorption energies are 62, 92 and 87 kcal mol⁻¹, for H, O and S, respectively. The calculated adsorbate---Ni bond distances of 1.86 Å for H, 1.86 Å for O and 2.29 Å for S are in good agreement with experimental data. SH and OH bonding to the surface involves a combination of ionic and covalent contributions and substantial mixing with the Ni 3d orbitals. Dipole-moment calculations indicate strong ionic bonding for the atomic O/Ni system and ionic plus covalent character for the atomic S/Ni interactions. Adsorption of S and O at the three-fold site blocks H adsorption at the nearby surface. Moving H away from the S or O adatom reduces the repulsion. The dissociation of SH_ad → S_ad + H_ad is calculated to be exothermic by 5 kcal mol⁻¹ and OH_ad → O_ad + H_ad to be endothermic by 30 kcal mol⁻¹ for infinite separation between S, O and H.