【摘要】 本文报导利用醋酸钴在酮类配位体存在下于冰醋酸溶剂中与氧分子作用,得到一种新型的对烃类的催化氧化具有良好的活性的催化剂。根据无素分析、差热热重分析、红外光谱、紫外可见光谱、质谱、核磁共振谱、磁化率和电导率等的测定结果,初步确定该配合物的结构是一种以羟基和羰基桥联的四核钴配合物[Co₂^ⅡCo₂^Ⅱ（μ₂-OH）₆（μ₂-HOAc）₂（AcO）₄]。更多还原

【Abstract】 In recent years, a four nuclear cobalt coordination compound ( Co2ⅡCo2Ⅲ(μ2-OH)6(μ2-HOAc)2(AcO)4 ) (hereafter designated as A) was synthesized as we carried out studies on the liquid -phase oxidation of alkanes.The test data shown that A had a high catalytic activity for liquid-phase oxidation of alkanes. The coordination compound was prepared from the cobalt acetate and a kind of organic ketone ligand with molecular oxygen in glacial acetic acid at 40℃. According to results of elemental analysis the chemical composition of A is Co4C12H24O18. The results of infrared spectra indicate that it is significantly different from cobalt acetate in vibrational absorptions. Carboxyl group stretching vibration ( va(coo)) of cobalt acetate is a single peak in the 1550-1650 cm-1 region while A has multiple peaks. The hydroxyl stretching vibration of A stronger than that of cobalt acetate in the 3200-3600 cm-1 region. From the above data, it is deduced that, the A probably is linked by hydroxyl bridge just as in the case of dinuclear cobalt coordination compound synthesized by earlier workers. When the ultraviolet-visible absorption of A was compared with that of cobalt acetate in acetic acid, it was found that the position of the strongest absorption peak has moved in the long wave length direction. Moreover, the strongest absorption peak is similar to the one of cobalt (Ⅲ ) absorption peak in the visible region. So it is concluded that A is a coordination compound containing Co (Ⅲ ) . The magnetic properties of A have been studied by Gouy method, and we discovered that it was paramagnetic. Therefore, it is impossible that the four cobalt atoms in A are all Co(Ⅲ). Since the molecular weight is 692.08, the effective magnetic moment μeff = 6.82 B.M. may be calculated.If A is assumed to contain two Co (Ⅱ ) of "high-spin" , and equation μe f f = ( S + 1 ) is used, the calculated effective magnetic moment (μef f = 6.48 B.M. ) is close to the experimental value. Therefore it can be concluded that the molecule of A contains two Co ( Ⅱ ) and two Co (Ⅲ ) .Thermal analysis for A shows that one endothermic peak and two exothermic peaks are present in the DTA thermograms. Undoubtedly, the lower-temperature exothermic peak at 221. 7℃ represents the breakdown of the coordinate bond between the cobalt ( Ⅱ ) and the acetic acid ligand. The higher-temperature exothermic peak at 346.2℃ is due to the breakdown of the coordinate bond between cobalt (Ⅲ) and acetic acid ligand. Both peaks are caused by the combustion of the acetic acid ligand. Furthermore, the TGA results indicate that the weight loss of lower-temperature exothermic peak corresponds to the weight of one mole of acetic acid, and the weight loss of the other exothermic peak corresponds to the weight of four moles of acetic acid,while the weight loss of the endothermic peak is approximately the weight of one mole of acetic acid. It is thus seen that the endothermic peak arises also from the breaking of coordinate bond between cobalt (Ⅱ ) and acetic acid ligand. However, the temperature (106.5) was too low to burn the acetic acid ligand and gave an endothermic effect.NMR hydrogen spectra were also taken for A. It was found that there are only two kinds of resonance peaks, at chemical shift σ = 5.0 ppm and σ = 3.5ppm respectively with peak area ratio 2:1.Because the solvent used was deuterated methanol, the protons in the hydro-xyls of the coordination compound may be deuterated and do not appear in the hydrogen spectrum. According to these measurement, the hydrogen peak at σ=5.0 ppm is assigned to the protons of the acetic acid ligand coordinated to cobalt (Ⅲ ), another hydrogen peak at σ = 3.5 ppm is assigned to the protons of the acetic acid ligand coordinated to cobalt ( Ⅱ ) . As the deshielding effect of cobalt ( Ⅲ ) to ethyl radical is stronger than that of cobalt ( Ⅱ ), so the NMR absorption of the protons would shift downfield. Coupled with the peak area ratio we can thus confirm that there are two acetic acid ligands in coordination to cobalt (Ⅱ) and f更多还原