Complex Zn11 porphyrin

The small spectral discrimination between CO, 02, and NO in the Fe(P) system as compared with the Ru(P) or Os(P) systems may also be due to the less pronounced 7T-donor ability of the Fe11 ion relative to the Ru11 or Os11 ion in a porphyrin system. The spectral differences between the nitrosyls and the dioxygen complexes are especially small. The a- or (3-bands indicated for these complexes (Series a, c, d, Table 13) fall in the range where the a- or 0-bands of the corresponding Zn11 porphyrins are observed (Xa for Zn(Proto-IX) 586 nm (43) for Zn (TPP) 548 nm, see Table 3). As... 

The effects in evidence are complex. There is clearly an electrostatic effect due to the central positive charge [Ei/2 MIV > M111 > M11]. Nonetheless, SnIV, GeIV, Fem, and Ptn complexes are more difficult to oxidize than are the metal-free porphyrins while in contrast the Zn11, Cd11, and... 

Because of the diversity of polyhedral geometries found in porphyrin complexes with metal cations, additional ligands exhibit many different coordination modes. In Fe11, Co11, Mn11, Zn11, etc. complexes with one extra ligand, MP-L, the metal ion is pushed out of the N4 plane, and the MN4 coordination unit can be described as a pyramid with the M metal atom in the apical position. 

Sapphyrins (39) are metallated with divalent metal aoetates in the presence of sodium acetate (Scheme 109).274 For the Zn11 and Co11 complexes, structure (44) was proposed with the dianionic macrocycle coordinating to the metal ion as a tetradentate ligand. These metallosapphyrins experience ring contraction to porphyrin complexes under mass spectral conditions. 

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