Structure and properties of iron–cyclam complex of 2-aminophenol

• Published in: Polyhedron Vol. 20; no. 6; pp. 493 - 499
• Main Authors: Vasconcellos, Luiz C.G, Oliveira, Cristiane P, Castellano, Eduardo E, Ellena, Javier, Moreira, Ícaro S
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 30.03.2001; Elsevier
• Subjects: 1,4,8,11-Tetraazacyclotetradecane; 2-Aminophenol; Chemistry; Chemistry, Inorganic & Nuclear; Crystallography; Iron–cyclam; Macrocycle; Physical Sciences; Quinone-related species; Science & Technology; X-ray structures; Iron–cyclam; Quinone-related species; 1,4,8,11-Tetraazacyclotetradecane; X-ray structures; 2-Aminophenol; Macrocycle; 1,4,8,11-tetraazacyclotetradecane; quinone-related species; RUTHENIUM(III); macrocycle; METAL; LIGAND; CIS; 2-aminophenol; 1,4,8,11-TETRAAZACYCLOTETRADECANE CYCLAM; iron-cyclam
• ISSN: 0277-5387
• DOI: 10.1016/S0277-5387(00)00621-5

The cis-[Fe(cyclam)Cl 2]Cl and trans-[Fe(cyclam)Cl 2]BF 4 complexes were prepared by a new synthetic procedure. These isomers were characterized by elemental analysis, electronic spectroscopy ( λ max=238, 334 and λ max=238, 302 and 355 nm for cis- and trans-[Fe(cyclam)Cl 2] +, respectively) and electrochemistry ( E 1/2=212 and 83 mV; vs. Ag ∣ AgCl, KCl 3.5 M, 25°C μ=0.1 M NaTFA, pH 3.0 for cis- and trans-[Fe(cyclam)Cl 2] +, respectively). The reaction of cis-[Fe(cyclam)Cl 2] + isomer with 2-aminophenol (catH 3) ligand yields the cis-[Fe(cyclam)(qH)] 2+ complex, where (qH) is the quinonoid oxidized form of the (catH 3) ligand that is originated by an intramolecular electron transfer reaction. The cis-[Fe(cyclam)(qH)](PF 6) 2 complex crystallizes in the space group P2 1/ n, with two different values for Fe–N bond length, due to the σ and π distinct contributions. The electrochemical analysis of this species shows three one-electron sequential processes: E 1/2 (I)=−316 mV, E 1/2 (II)=+361 mV and E 1/2 (III)=+1.013 mV assigned to (sqH/catH 3), (qH/sqH) and (Fe(III)/Fe(II)) redox process, respectively.