Characterization and catalytic activity of iron(III) mono(4- N-methyl pyridyl)-tris(halophenyl) porphyrins in homogeneous and heterogeneous systems

• Published in: Journal of molecular catalysis. A, Chemical Chemical, 1999-12, Vol.150 (1), p.251-266
• Main Authors: Prado-Manso, Cynthia M.C, Vidoto, Ednalva A, Vinhado, Fábio S, Sacco, Hérica C, Ciuffi, Katia J, Martins, Patrı́cia R, Ferreira, Antônio G, Lindsay-Smith, John R, Nascimento, Otaciro R, Iamamoto, Yassuko
• Format: Article
• Language: English
• Subjects: ( Z)-Cyclooctene epoxidation; Anionic matrix; Catalysis; Catalysts: preparations and properties; Cationic iron(III) porphyrin; Chemistry; Exact sciences and technology; General and physical chemistry; Porphyrin; Supported catalysts; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/S1381-1169(99)00216-2

The synthesis, characterization and catalytic activity of the cationic iron porphyrins Fe[M(4- N-MePy)TDCPP]Cl 2 and Fe[M(4- N-MePy)TFPP]Cl 2 in the epoxidation of ( Z)-cyclooctene by PhIO in homogeneous solution and supported on silica gel (SG), imidazole propyl gel (IPG) or SG modified with 2-(4-sulfonatophenyl)ethyl groups (SiSO 3) have been accomplished. When supported on IPG, both cationic FeP bind to the support via Fe–imidazole coordination. Fe[M(4- N-MePy)TDCPP]IPG contains a mixture of low-spin bis-coordinated Fe IIIP and high-spin mono-coordinated Fe IIIP species, whereas Fe[M(4- N-MePy)TFPP]IPG only contains high-spin mono-coordinated Fe IIIP. These FePIPG catalysts also contain Fe IIP species, whose presence was confirmed by EPR spectroscopy using NO as a paramagnetic probe. Both cationic FePs coordinate to SG through Fe–O ligation and they are present as high-spin Fe IIIP species. The cationic FePs supported on SiSO 3 − are also high-spin Fe IIIP species and they bind to the support via electrostatic interaction between the 4- N-methylpyridyl groups and the SO 3 − groups present on the matrix. In homogeneous solution, both Fe[M(4- N-MePy)TDCPP]Cl 2 and Fe[M(4- N-MePy)TFPP]Cl 2 have similar catalytic activity to Fe(TDCPP)Cl and Fe(TFPP)Cl, leading to cis-epoxycyclooctane yields of 92%. When supported on inorganic matrices, both FePs lead to epoxide yields comparable to their homogeneous analogues and their anchoring enables catalyst recovery and re-use. Recycling of Fe[M(4- N-MePy)TDCPP]SiSO 3 − shows that this FeP maintains its activity in a second reaction.