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.