SYNTHESIS, STRUCTURE, AND ELECTROCHEMISTRY OF AN ELECTRON-DEFICIENT MU-OXO PORPHYRINDIMER, [(TPPBR4)FE]O-2

The synthesis and structural and electrochemical properties of an elec tron deficient iron mu-oxo porphyrin dimer, romo-5,10,15,20-tetrapheny lporphyrinatoiron(III)), represented as [(TPPBr4)Fe]O-2, are reported. X-ray analysis indicates an FE-O-Fe angle of 177.4(5)degrees and an i nterplanar distance of 4.58 Angstrom between the two mean porphyrin pl anes. Opposite pyrrole rings on the same macrocycle are twisted by abo ut 25 degrees relative to each other so that the porphyrin skeleton di stortion is best described as a twisted saddle-shaped configuration. E lectrochemical studies reveal that the highly halogenated mu-oxo dimer is stable in PhCN and undergoes four one-electron oxidations and four one-electron reductions in a total of seven steps. The singly reduced and singly oxidized forms of the dimer were characterized by thin-lay er spectroelectrochemistry and ESR spectroscopy.