The Mossbauer spectra of the imidazole, pyridine, and piperidine adducts of a"8, , -tetraphenylporphyriniron(II) and protoporphyriniron(II) and the imidazole and pyridine adducts of the corresponding porphyriniron(III) chlorides have been measured. Only the heme compound could be obtained with piperidine because piperidine causes spontaneous reduction of iron(III) to iron(II) in porphyrin complexes. For the iron(II) cases, the imidazole and pyridine adducts show similar isomer shifts, while the piperidine adducts have slightly larger isomer shifts. Imidazole gives the smallest quadrupole splitting; piperidine gives the largest. For the iron(III) cases, imidazole gives a somewhat larger isomer shift than pyridine and causes a much greater quadrupole splitting than pyridine, in contrast to the iron(II) cases. These results are discussed in terms of differences in x-bcmding characteristics between the added ligand and the iron atom. Pyridine appears to have a greater affinity for heme than does piperidine.
Some simple classical current loop calculations have been carried out on the phthalocyanine ring. Data for the calculations have been supplied by some single-ring and multi-ring silicon and germanium phthalocyanines. Possible structural uses are forseen for the results.
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