Bromine, oxidation-reduction behavior

In another interesting study , the electrochemical oxidation and reduction of Ni(II) and Cu(II) complexes of a series of yS-octahalogenao-mm-tetrakis(p-X-phenylporphyrins, (where halo = Cl or Br and X = CH3, H, F, Br, COOMe, CF3, NO2) were investigated and the data were analyzed by means of the Hammett equation. Significant differences in electrochemical behavior were observed for the brominated porphyrins. Density functional calculations (DFT) suggested that these differences might be due to the differences in saddling-induced metal (dxj-yj) to porphyrin (a2u) orbital interaction between the Ni and Cu porphyrins. 

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