Stepwise Oxidative C–C Coupling and/or C–N Fusion of Zn(II) meso-Pyridin-2-ylthio-porphyrins

The synthesis and characterization of zinc(II) meso -pyridin-2-ylthio-porphyrins are presented in this manuscript. The (electro)chemical oxidation of [5-(pyridin-2-ylthio)-10,20-bis( p -tolyl)-15-phenylporphyrinato] zinc(II) or [5,15-bis(pyridin-2-ylthio)-10,20-bis( p -tolyl)porphyrinato] zinc(II) leads to the formation of one or two C-N bond(s) by intramolecular nucleophilic attack of the peripheral thiopyridinyl fragment(s) on the neighboring β-pyrrolic position(s) (C-N fusion reaction). In addition, the chemical oxidation of [5-(pyridin-2-ylthio)-10,20-bis( p -tolyl)porphyrinato] zinc(II), i.e. , bearing one free meso position, mainly affords the meso , meso -dimer. Further stepwise electrochemical oxidation selectively produces the mono and bis C-N fused meso , meso -dimer. The resulting pyridinium derivatives exhibit important changes in their physicochemical properties (NMR, UV-vis, CV) as compared to their initial unfused precursors. Also, the X-ray crystallographic structures of three unfused monomers, one unfused meso , meso -dimer, and two C-N fused monomers are presented.