Iron complexes containing electrochemically active diazocycle-bis(di-tert-butyl-phenol) ligands

Journal of the Brazilian Chemical Society

Luísa L. Mendes²  Christiane Fernandes²  Roberto W. A. Franco¹  Leonardo M. Lube¹  Sheng-hsuan Wei¹  Joseph H. Reibenspies¹  Donald J. Darensbourg¹  Adolfo Horn Jr.² 

[1] ,Universidade Estadual do Norte Fluminense Darcy Ribeiro Laboratório de Ciências Químicas Campos dos Goytacazes RJ ,Brazil

关键词: phenoxyl radical;    iron compounds;    diazocycle;    tert-butylphenol;    non-innocent ligand;   

DOI  :  10.5935/0103-5053.20140078

来源: SciELO

【 摘 要 】

Four N, O-donor ligands built on diazocycle platforms and containing bis(di-tert-butyl-phenol) as pendant arms were employed in the synthesis of iron(III) complexes, resulting in four mononuclear and one dinuclear complexes. The ligands are distinct with respect to the diazocycle backbone: piperazine (H2L1), diazepane/homopiperazine (H2L2), hexahydropyrimidine (H2L3) or hexahydropyrimidin-5-ol (H3L4). The molecular structure of compounds [FeL2Cl], 2, and [Fe2(L4)(HL4)Cl], 4, were solved by single crystal X-ray diffraction analysis. Electrochemical data showed that, in addition to the electrochemical process centered on the metal, the compounds show ligand-centered redox processes. Coulometric studies with concomitant UV-Vis analyses confirmed that compound 2 generated the phenoxyl species, while electron paramagnetic resonance (EPR) spectroscopy confirmed the radical formation for compounds 2, 4 and 5. Of interest was the observation that the compound in which the ligand can be oxidized easiest is the one where the metal center shows the lowest Lewis acidity.

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