【作者】 张婷婷；

【导师】 孙立成； 王梅；

【作者基本信息】 大连理工大学 ， 精细化工， 2008， 硕士

【摘要】 氢化酶能够高效催化质子的还原和氢气的氧化。自从氢化酶的晶体结构被揭示以来，氢化酶活性中心的结构和功能模拟引起了人们的广泛关注。研究者普遍认为，在靠近氢化酶活性中心位置存在着分子内碱基，这些碱基能够俘获质子，辅助金属中心催化氢气的异裂或者氢气的生成。本论文合成了一系列含分子内氮碱基的铁硫配合物，希望碱基的引入能够起到摆渡质子的作用。合成了一个含分子内碱基的不对称双取代的铁铁氢化酶活性中心模型配合物（μ-pdt）[Fe（CO）₃][Fe（CO）{κ²-（Ph₂PCH₂）₂NⁿPr}]（2），通过MS、IR、¹H NMR、³¹P NMR、EA和X射线单晶衍射对其进行了表征。研究表明，向配合物2的溶液中加入少量三氟甲磺酸时，同时生成铁氢铁化合物[2（FeHFe）]⁺和氮上质子化产物[2（NH）]⁺，当三氟甲磺酸的总量达到配合物2的3当量时，所有单质子化产物进一步质子化生成铁氢铁和氮上都质子化的双质子化产物[2（FeHFe）（NH）]²⁺。成功地分离得到配合物2的双质子化产物[2（FeHFe）（NH）]（OTf）₂，通过IR、¹H NMR、³¹P NMR和X射线单晶衍射对其进行了表征。配合物[2（FeHFe）（NH）]（OTf）₂的晶体结构中，两个氢之间的距离为3．934（?）。铁铁氢化酶活性中心模型配合物双质子化产物迄今为止未见文献报道，对于研究铁铁氢化酶活性中心催化质子还原和活化异裂氢分子具有重要意义。合成了两个含分子内碱基的二聚[2Fe2S]配合物[（μ-pdt）Fe₂（CO）₅（Ph₂PCH₂）₂NR-（μ-pdt）Fe₂（CO）₅]（4：R=ⁿPr；5：R=Ph），通过MS、IR、¹H NMR、³¹P NMR、EA和X射线单晶衍射对其进行了表征。通过循环伏安法测定了配合物4的电化学性质，其在醋酸存在时，在-2．29V电压下具有催化质子还原产氢功能。5-甲氧基-1H-苯并咪唑-2-硫醇与十二羰基三铁发生脱硫反应，生成氮杂卡宾碳与铁配位的[3Fe2S]配合物[Fe₃（μ₃-S）₂（C₈H₈N₂O）（CO）₈]（7），通过IR、¹H NMR、EA和X射线单晶衍射对其进行了表征。7的[3Fe2S]骨架与配合物[Fe₃（μ₃-S）₂（CO）₉]的结构相似。研究表明，卡宾碳与铁原子的键合具有双键性质，此外其与邻近的杂原子氮之间也具有部分双键性质。更多还原

【Abstract】 Hydrogenase enzymes can efficiently catalyze the reduction of proton or the oxidation of hydrogen. Since the crystal structure of hydrogenases was published, more and more efforts have been put on the bio-inspired structural/functional models of hydrogenases. It is thought that the active sites in both iron-only and nickel-iron hydrogenases possess an internal base near the metallic catalytic centers which can assist the heterolytic cleavage of hydrogen and the H-H bond formation between a proton and a hydride. In this thesis, a series of Fe/S complexes with the internal basic site as a proton relay were synthesized aiming at preparing structural/functional models for hydrogenases.An asymmetrically disubstituted diiron complex （μ-pdt）[Fe（CO）₃][Fe（CO）{κ²-（Ph₂P -CH₂）₂NⁿPr}] （2） was prepared as biomimetic model of the Fe-Fe hydrogenases active site. It was characterized by MS, IR, ¹H NMR, ³¹P NMR, EA and X-ray crystal diffraction. Upon addition of a small amount of HOTf to the solution of 2, two species appeared, theμ-hydride complex [2（FeHFe）]⁺ and the [2（NH）]⁺ complex. As 3 equiv HOTf was added, both of the complexes transfered to the complex [2（FeHFe）（NH）]²⁺. The complex [2（FeHFe）（NH）]（OTf）₂was successfully isolated, and characterized by IR, ¹H NMR, ³¹P NMR, and X-ray crystal diffraction. The distance between the two H atoms is 3.934（?） in the crystalline state of the complex [2（FeHFe）（NH）]（OTf）₂. The proton/hydride diiron model for the Fe-Fe hydrogenases active site has not been reported so far.Two dimeric diiron dithiolate complexes with the internal basic site [（μ-pdt）Fe₂（CO）₅（Ph₂PCH₂）₂NR（μ-pdt）Fe₂（CO）₅] （4: R =ⁿPr; 5: R=Ph） were prepared and characterized by MS, IR, ¹H NMR, ³¹P NMR, EA and X-ray crystal diffraction. Cyclic voltammograms of 4 were studied to evaluate its redox properties. It was found that complex 4 could catalyze electrochemical proton reduction at -2. 29 V in the presence of acetic acid.5-Methoxy-1H-benzoimidazole-2-thiol reacted with Fe₃（CO）₁₂ to produce a [3Fe2S] complex [Fe₃（μ₃-S）₂（C₈H₈N₂O）（CO）₈] （7）, which was characterized by IR, ¹H NMR, EA and X-ray crystal diffraction. The structure of 7 is similar with the complex [Fe₃（μ₃-S）₂（CO）₉]. The chemical bond between carbene and the Fe atom has double bond characteristics and the bonds between carbene and N atoms are also partial double bonds.更多还原