Studies On The Iron-sulfur Clusters Related To Hydrogenases

Dihydrogen is a clean and renewable fuel. Hydrogenases can efficiently catalyze the proton reduction, consequently mimicking the structure of the active center is important not only in theory, but also in applications solving energy issues. With Fe/S clusters being closely relevant to the active site of [Fe-Fe] hydrogenases, the syntheses, structures and electrochemistry of the iron-sulfur clusters have been investigated, main results in the thesis are as follows:1. Thiol RSH reacts with Fe3(CO)12 and Et3N in THF to afford [Et3NH][(μ-RS)Fe2(CO)6 (μ-CO)] (R= MeO2CCH2, Ph, Et), treating the salts with 2-C5H4NNCS,3-C5H4NNCS and EtNCS forms (μ-MeO2CCH2S)Fe2(CO)5(μ-k2N,S:k2C-2-C5H4NNHCS) (1), (μ-MeO2CCH2S)Fe2 (CO)6(μ-k2C,S-3-C5H4NNHCS) (2), (μ-MeO2CCH2S)Fe2(CO)6(μ-k2C,S-EtNHCS) (3); (μ-PhS) Fe2(CO)6(μ-k2C,S-EtNHCS) (4) and (μ-EtS)Fe2(CO)6(μ-k2C,S-EtNHCS) (5). These five metal complexes have been characterized by IR, NMR and X-ray crystallography, electrochemical study of 2 and 5 reveals that compounds 2 and 5 can efficiently catalyze H2 evolution with HO Ac a proton source.2. Reactions of [Et3NH][(μ-RS)Fe2(CO)6(μ-CS2)] with electrophiles have been probed in detail. With the electrophilic reagent being Me3SiCl, unexpected complexes (u-RS)Fe2(CO)6 (μ-k2C,S-C4H7OSCS) (R= Et, Ph,4-MeC6H4; C4H7O,2-tetrahydrofuryl; 6,7,9) are obtained, PPh3-substituted reaction of 7 gives (μ-PhS)Fe2(CO)5(μ-k2C,S-C4H7OSCS)(PPh3) (8). With the electrophilic reagent being PhCH2Br, (μ-MeO2CCH2S)Fe2(CO)6([μ-k2C,S-PhCH2SCS) (10) is formed as expected. In this chapter five metal complexes have been characterized by IR, NMR and X-ray crystallography.3. (1) PhCONH2 reacts with Me2CHCHO to form Me2CHCH(NHCOPh)2 (11), upon sulfuration (Me2C=CNHCSPh)2S (12) is obtained. Treating 12 with Fe3(CO)12 affords Fe2(C O)6(μ-k2N,C:k2S-Me2CHCH=NCSPh)(13).(2) After the complete reaction of PhCSNHPh with Fe3(CO)i2 in the presence of Et3N, addition of Fe3(CO)12 and Ph2PCl results in (μ-k2P,S-Ph2PS)Fe2(CO)6(μ-k2C,N-PhC=NPh) (15), [(μ-k2C,N-PhC=NPh)Fe2(CO)6(μ4-S)]2Fe2(CO)6 (16) and (μ-k2C,N-PhC=NPh)Fe2(CO)6(μ4-S) Fe2(CO)6(μ-SC(Ph)=NPh) (17). However, addition of CS2 and CH3I offers 17, (μ-CH3S)Fe2 (CO)6(μ-k2C,N-PhC=NPh) (18) and [(μ-k2C,N-PhC=NPh)Fe2(CO)6((μ4-S)Fe2(CO)6(μ-k2C,S-C SSMe) (19).(3) Treating N,N"-diallylbenzimidazole salt (20) with Me3COK affords an NHC, after addition of CS2. NHC+-CS2-(21) is synthesized.21 reacts in situ with Fe3(CO)i2 to generate (μ-k2C:k2S-NHC+-CS)[Fe2(CO)6]- (22). Electrochemical study of 22 has demonstrated that using HOAc as a proton source compound 22 can efficiently catalyze H2 production.(4) After the complete reaction of CH3COSK with Fe3(CO)l2, addition of Ph2PCl gives Fe2(CO)6(μ-k2S:k2C,P-MeCSOPPh2)(23).