Abstract
A new pentadentate-fluorinated N(4)S(thiolate) ligand was synthesized. Reaction with Fe(BF(4))(2)·6H(2)O gives a new thioether complex, [Fe(II)(CH(3)CN)(N3Py(pF)SEtCN)][BF(4)](2) (1), and on-metal deprotection gives the thiolate complex, [Fe(II)(CH(3)CN)(N3Py(pF)S)][BF(4)] (2). Reaction of 2 with NO forms a low-spin ground state (S = 1/2) {FeNO}(7) complex (3). Chemical reduction of 3 with cobaltocene gives a metastable intermediate spin S = 1 {FeNO}(8) complex (4). Protonation of 4 releases nitroxyl (HNO), as observed by ESI-MS and (31)P NMR trapping experiments with PPh(3). Complexes 1 and 2 were characterized by single-crystal X-ray crystallography, complexes 2-4 were characterized by EPR and FT-IR spectroscopies, and all iron complexes were characterized by (19)F NMR, UV-vis, and (57)Fe Mössbauer spectroscopies. These results show that a nonheme iron complex can generate and release HNO, suggesting that nonheme iron centers could be endogenous or exogenous sources of HNO in biological systems. Additionally, the fluorine-substituted N(4)S(thiolate) ligand provides a unique spectroscopic handle to monitor the reactivity of the iron center several bonds away from the fluorine substituent.