烷基锂分子中化学键的 ab initio 研究

本文用6-13G基函对3-12G基优化构型进行单点ab initio (从头计算法) 计算, 并根据轨道的组合系数、电荷密度图和键强参数等详尽地分析了烷基锂分子的成键情况。烷基锂的易挥发、易聚合、聚合物易溶于烃类溶剂中等物理、化学性质主要是其C－Li键具有显著的共价性缘故。由于烷基锂的C-Li键比C－H和C－C键的强度要小,故C-Li键易于断裂,使烷基锂表现有高的化学反应活性。     

Some new concepts on the nature of the covalent bond based on ab initio quantum-chemical calculations

The ground states of eight molecules and some of their hole states are calculated. The calculations are performed on a medium-size home-made computer using self-written programs. The basis set used is LEMAO-3G, with scaling factors of the orbitals optimized by means of a method using orthogonal array and finding minima of fitted quadric curves. The conclusions are: (1) The LCAO -MO method is the reflection of the interference effect due to the wave nature of electrons. (2) The mathematical methods of rescaling the orbital exponents is the reflection of the orbital contraction or diffusion occurring during the formation of MO . These conclusions are in agreement with the Virial theorem and the variation principle. They are also strongly supported by the photoelectron spectroscopy data. The calculated values of the energies of the valence orbitals are very near to those obtained by using some extended basis set, which are reported to be very close to the Hartree–Fock limits. From these results and discussions it may be concluded that the nature of the covalent bond should be considered as an interplay and mutual conditioning between the wave nature of the electronic motion on the one hand and the various attractive and repulsive factors on the other hand, among which the kinetic energy should be a very important repulsive factor. The mutual screening effects of the electrons in various MOS, which are different for different molecules, are also very important. This is perhaps one of the main causes of the differences in properties of different molecules.     

Nickel(II) and cobalt(II) complexes with a mixed donor acyclic ligand bearing heterocyclic moieties as terminal groups

New nickel(II) and cobalt(II) complexes of a symmetric acyclic mixed O,N,S-donor ligand, S,S-bis(8-quinolyl)-4-oxo-1,7-dithiaheptane (OESQ), with quinoline as the terminal group, [M(OESQ)(H₂O)](NO₃)₂ [M = Ni^II (1) and Co^II (2)], have been prepared and characterized by elemental analyses, u.v.–vis. and i.r. spectra, and by magnetic susceptibility measurement. Single X-ray diffraction analyses show that (1) and (2) are isomorphous. The nickel (or cobalt) ion in (1) [or (2)] is hexa-coordinated and the complex cation exhibits a slightly distorted-octahedral geometry defined by all five donor atoms of the ON₂S₂ of OESQ and a water, molecule with N₂S₂ in equatorial and two oxygens in axial position.     

Molecular structure and spectral characteristics of bis(S-methyl-N-(2-pyridyl)methylendithiocarbazato)nickel(II), (Ni(NNS)2)

A nickel(II) complex of the pyridine-2-aldehyde Schiff base of S-methyldithiocarbazate (HNNS) has been synthesized and characterized by means of elemental analysis, IR and UV-vis spectra. The crystal structure of the complex has been determined by single-crystal X-ray diffraction. The complex crystallizes in the monoclinic, space P2₁/c, with a = 14.092(2), b = 16.886(2), c = 8.857(2)Å; = 105.78(3) °, V = 2028.2(6) ų, and Z = 4. The nickel atom is octahedrally coordinated by two uninegatively charged tridentate Schiff base in a mer-configuration via the pyridine nitrogen atom, azomethine nitrogen atom, and mecaptide sulfur atom.     

红外光谱研究以非离子型表面活性剂所组成微乳液的水结构

由烷基聚氧乙烯醚(AEO9)/正己醇/正十六烷/水所组成的微乳液,采用红外光谱对水内核的微观结构进行研究。以水分子的OH伸缩振动谱带, 由高斯分布曲线面积得出不同结构水的含量。只有少量水与表面活性剂结合, 另有部分水束缚于聚氧乙烯链段之间, 这些水与水相中的自由水呈动态平衡。当体系在剧烈振动后, 少量结合水转为束缚水, 静止后又恢复原状。     

镍系胶体催化丁二烯聚合反应的研究Ⅲ: 催化剂组分的 红外光谱

已知在加氢汽油介质中Ni(naph)~2-Al(i-Bu)~3-(BF~3·OEt~2+n-C~8H~1~7OH)体系为胶体催化剂。本文应用FT-IR谱结合Tyndall效应,电导率,UV-Vis,ESR谱对催化剂各组分的相互作用进行研究。得出Ni(naph)~2被Al(i-Bu)~3还原的主要产物是Ni^0;被(i-Bu)~2AlO(i-Bu)还原的主要产物Ni^+(naph)^-,Ni^0聚结成胶粒(Ni^0)~n,胶粒表面的Ni^0或吸附的Ni^+是活性中心组分,与(i-Bu)~2AlBF~4形成配合物,给出了活性中心模型。丁二烯对形成活性中心无影响,仅起稳定胶粒的作用。