531505-15-4Relevant articles and documents
Dinuclear iron(II)-cyanocarbonyl complexes linked by two/three bridging ethylthiolates: Relevance to the active site of [Fe] hydrogenases
Liaw, Wen-Feng,Tsai, Wen-Ting,Gau, Hung-Bin,Lee, Chien-Ming,Chou, Shin-Yuan,Chen, Wen-Yuan,Lee, Gene-Hsiang
, p. 2783 - 2788 (2003)
Dinuclear iron(II)-cyanocarbonyl complex [PPN]2[Fe(CN)2(CO)2(μ-SEt)]2 (1) was prepared by the reaction of [PPN]-[FeBr(CN)2(CO)3] and [Na][SEt] in THF at ambient temperature. Reaction of complex 1 with [PPN][SEt] produced the triply thiolate-bridged dinuclear Fe(II) complex [PPN][(CN)(CO)2Fe(CO)2(CN)] (2) with the torsion angle of two CN- groups (C(5)N(2) and C(3)N(1)) being 126.9°. The extrusion of two σ-donor CN- ligands from Fe(II)Fe(II) centers of complex 1 as a result of the reaction of complex 1 and [PPN][SEt] reflects the electron-rich character of the dinuclear iron(II) when ligated by the third bridging ethylthiolate. The Fe-S distances (2.338(2) and 2.320(3) A for complexes 1 and 2, respectively) do not change significantly, but the FeII-FeII distance contracts from 3.505 A in complex 1 to 3.073 A in complex 2. The considerably longer FeII-FeII distance of 3.073 A in complex 2, compared to the reported Fe-Fe distances of 2.6/2.62 A in DdHase and CpHase, was attributed to the presence of the third bridging ethylthiolate, instead of π-accepting CO-bridged ligand as observed in [Fe] hydrogenases. Additionally, in a compound of unusual composition {[Na·5/2H2O][(CN)(CO)2Fe(μ-SEt) 3Fe(CO)2-(CN)]}n{1/2O(Et)2} n (3), the Na+ cations and H2O molecules combining with dinuclear [(CN)(CO)2Fe(μ-SEt)3Fe-(CO)2(CN)] - anions create a polymeric framework wherein two CN- ligands are coordinated via CN--Na+/CN--(Na+)2 linkages, respectively.
Preparative and structural studies on iron(II)-thiolate cyanocarbonyls: Relevance to the [NiFe]/[Fe]-hydrogenases
Chen, Chien-Hong,Chang, Yung-Su,Yang, Chien-Yeh,Chen, Tai-Nan,Lee, Chien-Ming,Liaw, Wen-Feng
, p. 137 - 143 (2007/10/03)
A number of thermally stable iron(II)-thiolate cyanocarbonyl complexes, cis,cis-[Fe(CN)2(CO)2(CS3-S,S)]2- (1), mer-[Fe(CO)2(CN)3 (NCCH3)]- (2) mer-[Fe(CO)3(CN)(CS3 -S,S)]- (3), cis-[Fe(CO)2(CN)(S(CH2)2S (CH2)2S(CH2)2S-S,S,S)]- (4), [Fe(CO)2(CN)3Br]2- (5), mer-[Fe(CO)2(CN)3(m-SC6H4Br)]2- (6) and mer-[Fe(CO)2(CN)3(SPh)]2- (7) were isolated and characterized by IR and X-ray diffraction analysis. The extrusion of one strong σ-donor CN- ligand instead of CO from the iron(II) center of the thermally stable complexes [FeII(CO)2(CN)3Br]2- (5) containing less electron-donating bromide reflects the electron-rich character of the mononuclear [FeII(CN)2(CO)2(CS3- S,S)]2- (1) when ligated by the bidentate thiolate, and the combination of one cyanide, two carbonyls and a tridentate thiolate provides the stable complex 4 as a result of the reaction of complex 5 and chelating ligand [S(CH2)2S(CH2)2 S]2-. The preference of the sixth ligand coordinated to the unsaturated [FeII(CO)(CN)2(CS3-S,S)]2- Fe(II) center, the iron-site architecture of the bimetallic Ni-Fe active-site of [NiFe] hydrogenases, is a strong π-acceptor CO group. Scrutiny of the coordination chemistry of iron(II)-thiolate cyanocarbonyl species [FeII(CO)x(CN)y(SR)z]n- reveals that certain combinations of thiolate, cyanide and carbonyl ligands(3 ≤ y + z ≤ 4) bound to Fe(II) are stable and this could point the way to understand the reasons for Nature's choice of combinations of these ligands in hydrogenases.
