The Synthesis Of Cyclopentadienyl Diazido Diiron Fe-S Cluster

Nitrogenase is the metalloenzyme that performs biological nitrogen fixation by catalyzing the reduction of N2 to ammonia. In contrast with the earlier, industrial synthesis of ammonia is the use of iron oxide catalyzed Haber-Bosch process, which need high operating pressure and reaction temperature.To be able to convert ammonia under mild conditions, chemists have made unremitting efforts over the years. In the 90s, the nitrogenase crystal structure was determined through the single crystal X-ray diffraction. Although the mechanism of the catalytic reduction by nitrogenase is still not clear, a high-valent azido-iron species was proposed to be a key possible intermediate during the process.In this thesis, in order to get a new iron nitride from the derivatives of cyclopentadiene sulfur-bridged dinuclear iron comolexes as a method to mimic biological metalloproteins, a series of novel Fe-S clusters [Cp+Fe(μ-SR)MeCN]2[PF6]2(la-lf) (Cp(?)=η5-C5Me4H, R=Et, la; Cp(?)=η5-C5Me4H, R=iPr, 1b; Cp(?)=η5-C5Me5, R=Me,lc; Cp(?)=η5-C5Me5, R=Et,1d; Cp(?)=η5-C5Me5, R=iPr, le; Cp(?)=η5-C5Me5, R='Bu, If) were prepared. And the reactions of the Fe-S cluster with azide compounds were still researched. The detailed contents are as follows:(1) The synthesis of cyclopentadienyl Fe-S clusters with acetonitrile as ancillary ligands. Treatment of [CptFe(μ-SR)CO]2 with NH4PF6 in acetonitrile under air atmosphere affords complexes [CptFe(μ-SR)MeCN]2[PF6]2 (la-lf).The yield:la=45%;1b=43%;1c=40%; 1d=41%; le= 39%; 1f=38%.They are fully characterized by IR,1H NMR spectroscopies and single-crystal X-ray diffraction method.(2) The reactions of la,1d with azide compounds. Complex la, 1d do not react with TMSN3 or AdN3 at room temperature. And when the reactions were heated, products were very complex and can not be determined. In the lower temperature(10-15℃) and the optimal ratio of the volume of acetone/methanol(Vactone:Vmethanoi=1:2), the complex 2 [Cp'Fe(μ-SEt) N3]2 was obtained in the high yield(85%) during the reaction of the complex la with 2eq.NaN3. The complex 2 is fully characterized by IR, 1H NMR spectroscopies and single-crystal X-ray diffraction method. Under the same conditions, complex 1d with sodium azide can not produce the similar reaction product.