A nitrosyl complex
of MnII-porphyrinate, [(F20TPP)MnII(NO)], 1 (F20TPPH2 = 5,10,15,20 tetrakis(pentafluorophenyl)porphyrin), was synthesized and
characterized. Spectroscopic and structural characterization revealed
complex 1 as a penta-coordinated MnII-nitrosyl
with a linear Mn–N–O (180.0°) moiety. Complex 1 does not react with O2. However, it reacts with
superoxide (O2
–) in THF at −80
°C to result in the corresponding nitrate (NO3
–) complex, 2, via the formation of a presumed
MnIII-peroxynitrite intermediate. ESI-mass spectrometry
and UV–visible and X-band EPR spectroscopic studies suggest
the generation of MnIV-oxo species in the reaction through
homolytic cleavage of the O–O bond of the peroxynitrite ligand
as proposed in NOD activity. The intermediate formation of the MnIII-peroxynitrite was further supported by the well accepted
phenol ring nitration which resembles the biologically well-established
tyrosine nitration.