Interactions of HNO With Metallated Porphyrins, Corroles, and Corrines

Abstract

In this chapter we describe the interaction of azanone and its donors with metallated porphyrins (MP), corroles (Cor), and corrines (Corr). We start describing the general reactivity of Fe, Mn, and Co porphyrins (P) in the different redox states regarding the stability of the resulting nitrosyl (NO) complexes, which are described and characterized as {Me(H)NO}6/7/8 adducts. Secondly, we compare the kinetics and mechanistic aspects of HNO and donor reactions with different porphyrins and compare them to those of heme-proteins. Finally, we introduce the more recently described reactivity of HNO with corroles and compare it to that of porphyrins. Main conclusions of the present chapter are that HNO reacts following a relatively fast bimolecular reaction mechanism (k=1×104 M−1s−1) with metal porphyrins. Iron (Fe) is the most promiscuous metal, being able to form several adducts varying in their redox state, while Mn and Co are far more specific and can thus be used as selective trapping agents. Last but not least, mechanistic analysis show that while reducing porphyrins react with free azanone, oxidizing porphyrins may react directly with the donors promoting their oxidative NO release.