Iron porphyrazine complexes

Subsequent reaction of porphyrazines 170 and 171 with Cu(OAc)2 resulted in the selective metalation within the macrocyclic cavity to provide the corresponding copper complexes 166 (62%) and 172 (47%). Treatment of pz 170 with manganese acetate and iron sulfate in dimethyl sulfate gave the dmso adducts 173 (70%) and 174 (85%), respectively (168). Axial ligation was also observed when other metals were incorporated such as cobalt acetate, nickel acetate, and zinc acetate to give the metal complexes 175 (83%), 176 (70%), and 177 (90%) as the hydrates. The axial ligand of... 

Porphyrazines (153) are porphyrins with the four =CH— inter-ring bridges replaced by =N—, thus forming a halfway house between porphyrins and phthalocyanines (next section). The octaethylporphyrazine complexes of iron(II) and of iron(III) have been reviewed. ... 

In contrast to the acid—base behavior of iron(III) porphyrin species, Fe (Pz) exists as an equilibrium mixture of monoaqua and diaqua complexes in acidic medium (46). The five-coordinate monoaqua iron(III) porphyrazine, [Fe (Pz)(H20)], which is the main species at low pH, is stabilized in the unusual intermediate spin state, S = 3/2. This behavior results from the fact that the porphyrazine ring is much smaller than that of the porphyrin and the iron(III) center has to be displaced out of the plane. At higher pH (pH = 10), a low-spin, six-coordinate aquahydroxido complex, [Fe (Pz)(H20)(0H)], is formed whereas a further increase in pH (pH = 13) results in the formation of the low-spin, dihydroxido complex, [Fe (Pz)(OH)2], for which no water exchange reaction could be observed (46). 

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