Mononuclear, Dinuclear Iron(Ⅱ)-Thiolate Complexes with Mixed CO/CN- Ligands：the Potential Model Compounds of [Fe]-only Hydrogenases

• Main Author: 周士元
• Other Authors: 廖文峰
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/61150365374725039429

碩士 === 國立彰化師範大學 === 化學系 === 90 === The tricarbonyl-cyano iron(Ⅱ)-thiolate complex mer- and fac-[PPN] [(CN)(CO)3Fe(S,S-CS)] (1) were prepared by the reaction of K2CS3 and [PPN][Fe(CO)3(CN)I2] which is obtained from oxidation addition of iodine to [Fe(CO)4(CN)]-. Photolysis of complex 1 in THF led to the formation of the dicarbonyl-dicyano iron(Ⅱ)-thiolate complex cis,cis-[PPN]2[(CN)2(CO)2Fe(S,S-CS)] (A). Reaction of [PPN][Fe(CO)3(CN)I2] and [Na][SEt] with 1：2 ratio led to the formation of polymeric {[Na．5/2H2O][(CN)(CO)2Fe (m-SEt)3Fe(CO)2(CN)]．1/2O(Et)2}n(2), the biomimetic model complex of [Fe]-only hydrogenases. There are two kinds of conformation in complex 2, the average FeⅡ-FeⅡ distance is 3.079Å and the torsion angle between two CN- ligands is 4.18ﾟ. The FeⅡ-FeⅡ distance in complex 2 is longer than those reported for the dinuclear iron subcluster (2.6/2.62Å observed in Dd and Cp) of [Fe] hydrogenases active-site isolated from C. pasteurianum and D. desulfuricans. It may be attributed to the third bridging ligand being ethylthiolate instead of bridging CO ligand. Reaction of [PPN][Fe(CO)3(CN)2Br] with 2 equiv. of [Na][SPh] produced the complex mer-[PPN]2[Fe(CN)3(CO)2(SPh)](3) and known trans-[PPN]2[Fe(CN)4(CO)2](4). Upon extended stirring, complex 3 converted to the more stable complex 4. We conclude that the total coordination number of cyanide and thiolate ligands surrounding Fe(II) center to stabilize Fe(II) complexes is 3 or 4 in the series of [FeII(CO)x(CN)y(SR)z]n- complexes.