Synthesis Of New Carboxylate-Bridged Cyclopentadienyl Fe-S Clusters

Fe-S clusters are widely found in the life as the active site of enzyme including the nitrogenase, hydrogenase, and ferredoxins. The carboxylate-bridged non-heme diiron centers can activate dioxygen in a variety of nature enzymes. Mimicing of biological metalloproteins have ever been a challenging topic. Recently, our group reported new cyclopentadienyl Fe-S cluster [Cp*Fe(u-SEt)3FeCp*] and the nitrogenase model complexes [Cp*Fe(μ-SRl)2(μu-η2-R2NNH)FeCp*] (R1= Me, Et; R2= Me, Ph) with excellent properties of catalytic cleavage of N-N single bond of hydrazines at diiron centers. Moreover, carboxylate-bridged complexes [(LMe)M2(μ-O2CR)] (M= Co, Ni, Zn, Fe; R= H, Me, Ph, CH=CHPh) can be obtained by the substitution reaction of complexes [(LMe)M2(μ-Cl)] (M= Co, Ni, Zn, Fe) with carboxylate ligand, LMe is a macrocyclic pocket ligand. In this thesis, for the simulation of biological activity of Fe-S clusters, ten new carboxylate-bridged cyclopentadienyl Fe-S clusters are successfully synthesized. The detailed contents are as follows:(1) The synthesis of cyclopentadienyl Fe-S clusters with acetonitrile as ancillary ligands. Treatment of [Cp*Fe(μ-SR)CO]2 with NH4PF6 in acetonitrile under air atmosphere affords complexes [Cp*Fe(μ-SR)MeCN]2[PF6]2 (1a, R= Et; 1b, R=tPr). 1a and 1b are fully characterized by IR,1H NMR spectroscopies and single-crystal X-ray diffraction method.(2) The synthesis of carboxylate-bridged cyclopentadienyl Fe-S clusters. Nine new complexes [Cp*Fe(μ-SEt)2(μ-η2-O2CR)FeCp*][PF6] (2a, R= H; 2b, R= CH3; 3a, R= Ph; 4a, R= CHCH2; 4b, R= CHCHPh; 5a, R= C≡CH; 5b, R= (CH2)2C=CH; 6a, R= CH(CH2)3NH; 6b, R= CH2NHBoc) are prepared by the substitution reaction of complex la with carboxylic sodium, and their electrochemistry are investigated. The complexes are fully characterized by IR,1H NMR spectroscopies and ESI-MS, moreover,2a,2b,3a,4b,5b and 6a are further characterized by single-crystal X-ray diffraction method.(3) The synthesis of [Cp*Fe(μ-SEt)2(μ-η2-O2CR)FeCp*][PF6] (7a) by click chemistry reaction of 5a and m6.7a is fully characterized by IR,1H NMR spectroscopies, ESI-MS, and single-crystal X-ray diffraction method.