Abstract
Abstract Reaction of Fe(CO)2(NO)2 and 8,8′-diquinolyl disulfide in THF afforded the trigonal bipyramidal, mononitrosyl iron complex [Fe(qt)2(NO)] (1) with NO occupying the equatorial position. For 1, a νNO stretching frequency of 1681 cm-1 (KBr) is observed. X-ray data reveals that Fe-N(NO) and N-O bond distances are 1.685 Å and 1.18 Å, respectively. Also, complex 1 contains a notably bent Fe-N-O bond, 157.8°.□□1H NMR (paramagnetic shift), EPR (S = 1/2), magnetic moment data (□eff = 1.63 □B) and the chemical reactivity of complex 1 agree with a electronic configuration of {FeII(NO•)}7 according to the Feltham-Enemark notation. Reaction of [Fe(qt)2(NO)] (1) and [NO][BF4] in THF afforded a EPR-silent, homodinuclear iron thiolate nitrosyl complex [(ON)Fe(1)(qt)2Fe(2)(NO)2][BF4] (2). The geometry of Fe(1) of complex 2 is trigonal bipyramidal [(ON)FeN2S2] core with a NO ligand occupying the equatorial position and the Fe(2) center has a regular tetra- hedral [S2Fe(NO)2] coordination environment. The Fe(1)-Fe(2) distance of 2.661 Å implicate the existence of Fe-Fe interaction. The average Fe-N(NO) and N-O bond distances of complex 2 are 1.660 Å and 1.155 Å, respectively. Complex (NO)4Fe2(□-SPyPep)2 (7) was afforded by reaction of Fe(CO)2(NO)2 and (PyPepS)2 [(PyPepS)2 = N-2-mercapto-phenyl-2′-pyridinecarboxamide disulfide] in THF. Complex 7 was oxidized by O2 to yield the EPR-silent, homodinuclear iron thiolate nitrosyl complex (NO)2Fe2(PyPepS)2 (3). Complex 3 consists of two distorted square pyramidal structure with a Fe(1)-Fe(2) bond distance of 2.625 Å. The average Fe-Ncarboxamide and Fe-S bond distances of complex 3 are 1.949 Å and 2.243 Å, respectively. Each iron center of complex 3 is ligated by one carboxamido N, one pyridinyl N, two bridged thiolato S and a NO molecule. This unique coordination environment of 3 may provide important clues (structure, spectroscopy, reactivity, etc.) relating to the nitrile hydratase.