Proton-Induced Reactivity of NO– from a {CoNO}8 Complex

Research on the one-electron reduced analogue of NO, namely nitroxyl (HNO/NO–), has revealed distinguishing properties regarding its utility as a therapeutic. However, the fleeting nature of HNO requires the design of donor molecules. Metal nitrosyl (MNO) complexes could serve as potential HNO donors. The synthesis, spectroscopic/structural characterization, and HNO donor properties of a {CoNO}8 complex in a pyrrole/imine ligand frame are reported. The {CoNO}8 complex [Co­(LN4PhCl)­(NO)] (1) does not react with established HNO targets such as FeIII hemes or Ph3P. However, in the presence of stoichiometric H+ 1 behaves as an HNO donor. Complex 1 readily reacts with [Fe­(TPP)­Cl] or Ph3P to afford the {FeNO}7 porphyrin or Ph3PO/Ph3PNH, respectively. In the absence of an HNO target, the {Co­(NO)2}10 dinitrosyl (3) is the end product. Complex 1 also reacts with O2 to yield the corresponding CoIII-η1-ONO2 (2) nitrato analogue. This report is the first to suggest an HNO donor role for {CoNO}8 with biotargets such as FeIII-porphyrins.