Water Soluble FeII-HNO Porphyrin Complex: Bimolecular Reaction Kinetics

JUAN PELLEGRINO; AGOSTINA M. MAZZEO; FABIO DOCTOROVICH

Iguazú

Simposio; SILQCOM6; 2017

Water Soluble FeII-HNO Porphyrin Complex: Bimolecular Reaction Kinetics Agostina M. Mazzeo1, Juan Pellegrino1, Fabio Doctorovich11DQIAQF/INQUIMAE, FCEN/CONICET, Universidad de Buenos Aires, Argentinaamazzeo@qi.fcen.uba.ar HNO and iron-nitroxyl complexes hold remarkable chemical properties and biological relevance.1 The protonated adduct might be stabilized by amino acids,2 and bulky substituents.3 The stability reported for [Fe(CN)5(HNO)]3? 4 led us to consider that factors like H-bonds with water, could stabilize the Fe-HNO moiety.The {FeNO}8 adduct of the water-soluble porphyrin TPPS was obtained from FeIIITPPS and characterized by UV-Vis spectroscopy. The product reoxidizes to the {FeNO}7 species within minutes, much slower than in organic media.5 Many hypotheses regarding the nature of this decomposition were considered, including the presence of adventitious oxygen and the identity of the reducing agent and its byproducts. Different effects were studied in order to determine the cause. Our conclusion is that a bimolecular reaction of [FeII(TPPS)HNO]4? takes place to give [FeII(TPPS)NO]4? and H2 gas. Kinetic and gas evolution measurements were made in order to obtain results that support this hypothesis. REFERENCES1.Doctorovich et al Coord. Chem. Rev. 2011, 255, 2764-2784.2.Lin et al J. Am. Chem. Soc. 2000, 122, 2393?2394.3.Goodrich et al, Inorg. Chem 20134.Montenegro, et al Angew. Chemie Int. Ed. 2009, 48. 4213−4216. 5.Pellegrino, et al J. Am. Chem Soc. 2010, 132. 989-995