Metalloporphyrins cadmium porphyrins

Heterodinuclear metalloponhyrin, postulated in the metalloporphyrin fomiation catalyzed by mercury(II) or cadmium(Il)10 12 was detected kinetically in the reaction of zincfll) or copper(ll) with homodinuclear mercury(II) porphyrin complex of Hg2tpps2 - The following biphasic reaction was observed ... 

Metalloporphyrins also have more symmetrical macrocycles than free-base porphyrins, so that their Q band spectra generally consist of only two bands. The pictorial classification denotes these as a- and bands, the former at longer wavelength than the latter. The relative intensities of these two bands can be a qualitative yardstick of just how stable is the metal com-plexed to the four porphyrinic nitrogen atoms. Thus, when a > 3, the metal forms a stable square-planar complex with the porphyrin, e.g. Ni(II), Pd(II), and Sn(IV). Cadmium(II), on the other hand, which is easily displaced by protons, has 3 > a. 

The electrochemistry of zinc, cadmium, and mercury porphyrins is uncomphcated and only macrocycle-centered electrode reactions are observed in nonaqueous solvents [7, 21]. Metalloporphyrins with this type of metal ion have been studied in some detail, but the best characterization of the electrochemical reaction products has been obtained with zinc porphyrins... 

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