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

The cis-[Fe(cyclam)Cl-2]Cl and trans-[Fe(cyclam)Cl-2]BF4 complexes were pre pared by a new synthetic procedure. These isomers were characterized by ele mental analysis, electronic spectroscopy (lambda (max) = 238, 134 and lambd a (max) = 238, 302 and 355 nm for cis- and trans-[Fe(cyclam)Cl-2](+) respec tively) and electrochemistry (E-1/2 = 212 and 83 mV; vs. Ag \ AgCl, KCl 3.5 M,25 degreesC mu = 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-a minophenol (catH(3)) ligand yields the cis-[Fe(cyclam)(qH)](2+) complex, wh ere (qH) is the quinonoid oxidized form of the (catH(3)) ligand that is ori ginated by an intramolecular electron transfer reaction. The cis-[Fe(cyclam )(qH)](PF6)(2) complex crystallizes in the space group P2(1)/n, with two di fferent values for Fe-N bond length, due to the sigma and pi distinct contr ibutions. The electrochemical analysis of this species shows three one-elec tron 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(I I)) redox process, respectively. (C) 2001 Elsevier Science B.V. All rights reserved.