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Published on: August 18, 2012
Spin State Dependent Reactivity of Iron-Nitrosyls With Dioxygen
Riya Ghosh1, Ankur K Guha2, Biplab Mondal1
1Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, Assam, India.
None:
Two iron nitrosyls, 2a and 2b, having {Fe(NO)}7 configuration but different spin states have been synthesized in Pz2Py [Pz2Py = bis(di(3,5-dimethyl-1H-pyrazolyl)methyl)-(2-pyridylmethyl)amine] ligand framework and have been characterized spectroscopically. In addition, the high-spin nitrosyl complex, 2a was also characterized structurally. FT-IR studies show that the nitrosyl stretching, νNO appears at 1790 and 1711 cm-1 for high-spin and low-spin analogues, respectively. The dioxygen reactivity of complexes 2a and 2b have been explored. The high-spin complex, 2a was found to react spontaneously with O2, leading to the formation of the corresponding nitrate (NO3‾) product, 3a through a presumed peroxynitrite intermediate. In contrast, dioxygen substitutes the NO group from complex 2b, owing to the weaker Fe-NNO bond, resulting in the formation of [FeIII(Pz2Py)(OH)(CH3CN)](ClO4)2, 3b. The release of NO by O2, in this case, was evident from the presence of NO2 in the GC-Mass of the headspace gas from the reaction vessel.
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