Synthesis, characterization and crystal structure of a dinuclear iron nitrosyl complex with 2-mercapto-1-[2-(4-pyridyl)-ethyl]-benzimidazolyl

A new dinuclear iron nitrosyl complex [Fe2(C14H12N3S)2(NO)4] (1) (C14H12N3S = 2-mercapto-1-[2-(4-pyridyl)-ethyl]-benzimidazolyl) has been obtained by the reaction of Fe(NO)2(CO)2 with 2-mercapto-1-[2-(4-pyridyl)-ethyl]-benzimidazole in CH3OH under moderate condition. Complex 1 was characterized by IR, UV-vis, electrochemistry and single crystal X-ray diffraction. IR spectrum displays two strong characteristic NO stretching frequencies (νNO) in solution and in solid state. Cyclic voltammetry shows one irreversible, two quasi-reversible and two reversible one-electron reductions and irreversible oxidizations. This result is consistent with the fact that complex 1 is very unstable and ready to lose NO in the air. As showing in the single crystal X-ray diffraction, complex 1 forms a “chair-shape” structure by the connections of two iron centers and S-C-N frames of benzimidazole. The dihedral angle of benzimidazole ring and 2Fe-2S plane is 73.6°. The crystal data are the following: 1, monoclinic, space group P2(1)/c, a = 10.43940(10) Å, b = 16.0900(2) Å, c = 10.13240(10) Å, α = 90°, β = 111.0940(10)°, γ = 90°, V = 1587.89(3) Å3, Z = 4.