Abstract
Mn(III) bis-porphyrins 2 and 3 were synthesized. The two porphyrin moieties, derived from the robust 5, 10, 15, 20-tetra(2,6-dichlorophenyl)porphyrin 1, are connected through a rigid spacer. In the presence of the bidentate imidazole ligand 4, Mn(III) bis-porphyrins should give the inclusion complex (D) with a very high binding constant, thus minimizing, at equilibrium, the concentration of the noncoordinate ligand in solution. The formation of (D) was supported by UV-Vis titration data and by MS-FAB+ studies. For the first time metal complexes of bis-porphyrins have been used as catalysts in oxygenation reactions. In the presence of 4 catalytic activity of 2 and 3 are comparable to that of the Mn(III) complex of 1.
Riassunto
Sono state sintetizzate Mn(III) porfirine dimere, in cui le due unità porfiriniche, derivate dalla chimicarnente robusta 5, 10, 15, 20-tetra(2,6-diclorofenil)porfirina 1, sono collegate da un gruppo spaziante rigido, come in 2 e 3. In presenza del legante bis-imidazolico 4, le Mn(III) porfirine dimere dovrebbero fornire un complesso di inclusione (D), con una assai elevata costante di coordinazione, cosi da ridurre al minimo la presenza di legante non coordinato all’equilibrio in soluzione. La formazione di (D) ha trovato conferma nei risultati della titolazione UV-Vis e dello studio MS-FAB+. Per la prima volta complessi metallici di porfirine dimere sono stati usati come catalizzatori in reazioni di ossigenazione. In presenza di 4 l’attività catalitica di 2 e 3 è confrontabile con quella del complesso di Mn(III) della porfirina 1.
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Nella seduta del 13 febbraio 1993.
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di Banfi, S., Montanari, F., Pozzi, G. et al. Mn(III) bis-porphyrins as catalysts in H2O2 alkene epoxidations in the presence of a lipophilic bidentate imidazole ligand. Rend. Fis. Acc. Lincei 4, 207–212 (1993). https://doi.org/10.1007/BF03001575
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DOI: https://doi.org/10.1007/BF03001575