Investigation On Biomimetic Chemistry Of The [FeFe]-and [NiFe]-Hydrogenase Active Sites

Hydrogenases can catalyze the biological conversion between protons and dihydrogen.[FeFe] and [NiFe]-Hydrogenases are two classes of most important. Recently, the research on the structural and functional aspects has received great attention in both organometallic chemistry and bioinorganic chemistry, not only because of their theoretical interest but also the practical importance for solving the increasingly environmental pollution and energy crisis. In order to develop the biomimetic chemistry of [FeFe]-hydrogenases and [NiFe]-hydrogenases, we carried out studies on synthesis, structures, properties and functions of new models for [FeFe]-and [Ni-Fe]-hydrogenase active sites. The main results described in this thesis are as follows:1, A total of28new compounds were successfully synthesized. The structures of these compounds were fully characterized by elemental analysis, IR,1H-NMR and some of them were further characterized by31P-NMR,13C-NMR,77Se-NMR and125Te-NMR spectroscopies, In addtion,20representatives were determined by X-ray diffraction analysis, and some representatives were investigated by electrochemistry.2, In chapter two, Firstly, we improved the synthetic method for preparation of the starting materials (μ-Te2)Fe2(CO)6, and synthesized the model complex [(μ-TeCH2)2CH(OH)]Fe2(CO)6(B) and improved the yield of model complex [(μ-TeCH2)2CH2]Fe2(CO)6(A). Then through substitution reactions, a series of model complexes (μ-PDTe)Fe2(CO)5(Li)(1, L=PPh3;2, PPh2H;3, PMe3;4, IMes),[(μ-PDTe)Fe2(CO)5]2(L2)(5, L2=dppf;6, dppp;7, dppb) and (μ-PDTe)Fe2(CO)4(L3)(8, L3=dppm;9, dppn) were prepared. All the ten new complexes were determined by X-ray diffraction analysis except for complex3and8. In addition, a study on electrochemical and electrocatalytic properties of the model complex8was also carried out.3, In chapter three, the μ-CO containing intermediate butterfly Fe/E clusters [(μ-CO)(μ-DtpSe)Fe2(CO)6]·[Et3NH](3),[(μ-CO]-(μ-DtpTe)Fe2(CO)6][Ph4P]/[PPN](Ph4P,4; PPN,6)[(μ-CO)-(μ-DtpTe)Fe2(CO)6](12-crown-4)Li (7)were successfully isolated by direct separation, exchange with cation and coordination with crown ether.4, In chapter three, we designed a new route to synthesis the [FeFe]-hydrogenase models, which can combine the μ-CO Fe/S cluster and hydrogenase model together. The [FeFe]-hydrogenases models [(μ-SCH2)(μ-POCl)CH2]Fe2(CO)6(9) and [(μ-SCH2)(μ-POPh)CH2]Fe2(CO)6(10) were prepared by treatment of the μ-CO anion (generated in situ from Fe3(CO)12, Et3N and2-hydroxyethanethiol)with with electrophilic reagent halogenated phosphine.5, In chapter four, two types of [NiFe]-hydrogenase model complexes [(μ-E)2-(2,2-bpy)Fe2(CO)6Ni (E=S,1; Se,2) and {NiFe[E(CH2)3E](dppb)(CO)3}(E=S,5; Se,7) containing the [N2E2] and [P2E2] units were prepare. The Hred model complexes{HNiFe[E(CH2)3E](dppb)(CO)3}BF4(E=S,6; Se,8) were prepared from complexes5and7reacting with HBF4·Et2O, respectively. It is worth to note that we synthesized the dual-core [NiFe]-hydrogenase models containing μ-Se for the first time. In addition, a comparative study on electrocatalytic properties of the model complexes6and8was carried out.