Direct Reduction of NO to NO by a Mononuclear Nonheme Thiolate Ligated Iron(II) Complex via Formation of a Metastable {FeNO} Complex.

Addition of NO to a nonheme dithiolate-ligated iron(II) complex, Fe(MeTACN)(SSiMe) (), results in the generation of NO. Low-temperature spectroscopic studies reveal a metastable six-coordinate {FeNO} intermediate ( = 3/2) that was trapped at -135 °C and was characterized by low-temperature UV-vis, resonance Raman, EPR, Mössbauer, XAS, and DFT studies. Thermal decay of the {FeNO} species leads to the evolution of NO, providing a rare example of a mononuclear thiolate-ligated {FeNO} that mediates NO reduction to NO without the requirement of any exogenous electron or proton sources.