Confused porphyrins

The DA reactions with o-benzoquinodimethane have also been extended to nickel(II) N-confused porphyrin 14 to yield nickel(II) A-confused isoquinoporphyrin 15 (... 

It is noteworthy to mention that employment of silver(i) trifluoroacetate in place of silver(i) acetate, as in the case of A-confused porphyrin, did not give the desired products. This has been attributed to the better basicity of the acetate anion than the trifluoroacetate, which aided the deprotonation of the three interior GH/NH protons at the carbaporphyrin ligand. Besides, it has been noticed that an excessive amount of silver acetate was required for the synthesis. The mechanism of the silver insertion reaction for this type of ligands was proposed, according to what Bruckner had proposed for the synthesis of silver(m) w -triarylcorroles.218,236 The reaction was suggested to occur via a disproportionation reaction, with the supportive observation of silver deposit formation after the reaction.237... 

M = Eu(III), Y(III), Lu(III)] 8-16%. These protonated compounds were isolated as the sole product, in contrast to the similar reactions with TBPPH2, where the non-protonated analogues Lnnl(Pc)(TBPP) (TBPP, 5,10,15,20-tetrakis[(4- ert-butyl)phenyl]-porphyrin) were obtained instead [106]. These results clearly show that the inversion of a pyrrole ring in N-confused porphyrins can stabilize the protonated complexes. 

The unnatural porphyrin family still fascinates the imagination. This year, to give a flavor for the diversity, there has appeared hybrid calixphyrins <00OL3103>, doubly A-confused porphyrins , unsymmetrical porphyrins attached to a modified 5,10,15,20-tetra (4-(2-trimethylsilylethynyl)phenyl]-21-23-dithiaporphyrin <00TL3709>,... 

Nay zeolite, intercalation in, 12, 828-829 TV-confused porphyrin system, and silver(III) complexes,... 

The structure of N-confused porphyrin 88 (Fig. 27) was first proposed in 1943 by S. Aronoff and M. Calvin (the future Nobel laureate) during a reexamination of Rothemund s synthesis of tetraphenylporphyrin [47], However, no convincing proof for such a structure was provided and only two of the six pigments isolated... 

The influence of tautomerism on aromaticity observed in N-confused porphyrin is echoed in the properties of its metal complexes. Depending on the oxidation state of the metal ion, the macrocycle adjusts its protonation level to yield a neutral complex. Divalent ions, such as Ni(II) [220], preferably form complexes of the general formula 91 (Fig. 28), whereas trivalent ions, such as Ag(III) give structures... 

Stability and aromaticity of multiply N-confused porphyrins were systematically investigated using DFT calculations [236, 239], Ignoring tautomerism, there are... 

In spite of its unusual structural outcome, the N-fusion reaction is a very general process. It was observed in a number of other N-confused macrocycles. For instance, an N-fused intermediate forms in the synthesis of trans doubly N-confused porphyrin 96 [238], N-fusion was also induced by the reaction with PhBCl2, in which case the reaction was promoted by the small radius of the coordinating boron(III) center [251], The resulting boron complexes were also aromatic, even though in some cases further chemical modification of the macrocycle took place (as in 110). The fusion process, which appears to be a nucleophilic addition-elimination, is reversible, and N-fused macrocycles can often be reopened when treated with nucleophiles such as alkoxides [248, 249],... 

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