One-pot dodecanitration of Zn(II) and Ni(II) meso-tetrakis-(2,6-dichlorophenyl) porphyrin, and extreme redox properties of the obtained complexes

Introduction of 12 nitro substituents on Zn(II) and Ni(II) [meso-tetra-(2,6-dichlorophenyl)porphyrin=TDCPP] was performed by adapting a recently described method for polynitration of metalloporphyrins, allowing the one-pot synthesis of metallododecanitroporphyrins from commercially available compounds. The corresponding complexes exhibit the highest reduction potentials ever described for such metalloporphyrins, which are shifted by more than +1.6 V when compared with those of Zn and Ni(TDCPP). The Ni (dodecanitroporphyrin) complex underwent four successive, reversible one-electron reductions between +470 and −555 mV (vs. SCE). The one-electron reduction product of the Ni dodecanitroporphyrin is stable for hours at room temperature even in aerobic conditions; its visible and EPR spectra indicate a Ni (porphyrin radical anion) structure.