title: Electronic effects of electron-donating and -withdrawing groups in model complexes for iron-tyrosine-containing metalloenzymes.
abstract: Three new iron(III) complexes with the ligand N,N'-bis(2-hydroxybenzyl)-N,N'-bis(pyridin-2-ylmethyl)ethylenediamine, H2bbpen, containing electron-donating and -withdrawing groups (Me, Br, NO2) in the 5-position of the phenol rings were synthesized and fully characterized by IR spectroscopy, ESI mass spectrometry, and CHN elemental analyses. X-ray structures of the iron(III) complexes containing NO2 and Me groups were determined. The effects of the substituents on the electronic properties of the complexes were detected by UV-visible spectroscopy, cyclic voltammetry, and X-ray crystallography. Linear correlations between the Hammett parameter for the substituents (sigma(p)) and the Fe(III)/Fe(II) redox potentials or ligand-metal charge-transfer (LMCT) processes of the complexes were obtained. A theoretical study using DFT is presented and shows good agreement between the experimental and calculated data.
authors.affiliation: Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC, Brazil.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Lanznaster
authors.forename: Ademir
authors.initials: A
authors.lastname: Neves
authors.forename: Adailton J
authors.initials: AJ
authors.lastname: Bortoluzzi
authors.forename: Aline M C
authors.initials: AM
authors.lastname: Assumpção
authors.forename: Ivo
authors.initials: I
authors.lastname: Vencato
authors.forename: Sergio P
authors.initials: SP
authors.lastname: Machado
authors.forename: Sueli M
authors.initials: SM
authors.lastname: Drechsel
mesh_terms: D018360:Crystallography, X-Ray; D004563:Electrochemistry; D004583:Electrons; D004798:Enzymes / Q000737:chemistry*; D005029:Ethylenediamines / Q000737:chemistry*; D005290:Ferric Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D008024:Ligands; D008667:Metalloproteins / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D011725:Pyridines / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D014443:Tyrosine / Q000737:chemistry*
chemical_list: D004798:Enzymes; D005029:Ethylenediamines; D005290:Ferric Compounds; D008024:Ligands; D008667:Metalloproteins; C516276:N,N'-bis(2-hydroxybenzyl)-N,N'-bis(pyridin-2-ylmethyl)ethylenediamine; D011725:Pyridines; D014443:Tyrosine