Abstract
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) 2 Fe(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) Å for complexes 1 and 2, respectively) do not change significantly, but the Fe II -Fe II distance contracts from 3.505 Å in complex 1 to 3.073 Å in complex 2. The considerably longer Fe II -Fe II distance of 3.073 Å in complex 2, compared to the reported Fe-Fe distances of 2.6/2.62 Å 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·5/2H 2 O][(CN)(CO) 2 Fe(μ-SEt) 3 Fe(CO) 2 -(CN)]} n {1/2O(Et) 2 } n (3), the Na + cations and H 2 O molecules combining with dinuclear [(CN)(CO) 2 Fe(μ-SEt) 3 Fe-(CO) 2 (CN)] - anions create a polymeric framework wherein two CN - ligands are coordinated via CN - -Na + /CN - -(Na + ) 2 linkages, respectively.