Reactivity of pentacoordinate ferrous porphyrins with exo-bidentate nitrogenous bases. Mononuclear and binuclear complexes in dynamic equilibrium

The reaction of several exo-bidentate nitrogenous bases with thiocarbonyl(5,10,15,20-tetraphenylporphinato)iron(II) afforded six-coordinate mononuclear and binuclear porphyrin complexes in dynamic equilibrium. This reaction was carried out in halocarbon solvents and monitored both spectrally and electrochemically. Within the potential limits of the solvent/supporting electrolyte system, each complex underwent at least four separate electron-transfer reactions with retention of the thiocarbonyl ligand. An electron-transfer pathway is presented and supported by the combined results of infrared and electronic absorption spectra, variable-temperature proton NMR, variable-temperature electrochemical, and spectroelectrochemical experiments. 46 references, 5 figures, 2 tables