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Electrochemical Polymerization of Iron(III) Polypyridyl Complexes through C-C Coupling of Redox Non-innocent Phenolato Ligands
- Source :
- Inorganic Chemistry, 56(1), 470-479. AMER CHEMICAL SOC, © Inorganic Chemistry, 2017, vol. 56, núm. 1, p. 470-479, Articles publicats (D-Q), DUGiDocs – Universitat de Girona, instname
- Publication Year :
- 2017
-
Abstract
- Phenolato moieties impart redox flexibility to metal complexes due their accessible (oxidative) redox chemistry and have been proposed as functional ligand moieties in redox non-innocent ligand based transition metal catalysis. Here, the electro- and spectroelectrochemistry of phenolato based μ-oxodiiron(III) complexes [(L1)Fe(μ-O)Fe(L1)]2+ (1) and [(L2)Fe-(μ-O)Fe(L2)]2+ (2), where L1 = 2-(((di(pyridin-2-yl)methyl)-(pyridin-2-ylmethyl)amino)methyl)phenol and L2 = 3, 5-di-tert-butyl-2-(((di(pyridin-2-yl)methyl)(pyridin-2-ylmethyl)amino)-methyl)phenol, is described. The electrochemical oxidation of 1 in dichloromethane results in aryl C-C coupling of phenoxyl radical ligand moieties to form tetra nuclear complexes, which undergo subsequent oxidation to form iron(III) phenolato based polymers (poly-1). The coupling is blocked by placing tert-butyl groups at para and ortho positions of phenol units (i.e., 2). Poly-1 shows two fully reversible redox processes in monomer free solution. Assignment of species observed during the electrochemical and chemical {(NH4)2[CeIV(NO3)6]} oxidation of 1 in acetonitrile is made by comparison with the UV-vis-NIR absorption and resonance micro-Raman spectroelectrochemistry of poly-1, and by DFT calculations, which confirms that oxidative coupling occurs in acetonitrile also. However, in contrast to that observed in dichloromethane, in acetonitrile, the oligomers formed are degraded in terms of a loss of the Fe(III)-O-Fe(III) bridge by protonation. The oxidative redox behavior of 1 and 2 is, therefore, dominated by the formation and reactivity of Fe(III) bound phenoxyl radicals, which considerably holds implications in regard to the design of phenolato based complexes for oxidation catalysis The European Research Council (StG, no. 279549, D.U.,W.R.B.) and the Ministry of Education, Culture and Science(Gravity program 024.001.035, W.R.B.), the Ministerio de Economia y Competitividad (MINECO, projects CTQ2014-59212-P and CTQ2015-70851-ERC, M.S.), the DIUE of the Generalitat de Catalunya (project 2014SGR1202, M.S.), and the European Fund for Regional Development (FEDER, UNGI10-4E-801, M.S.) are acknowledged for financial support. A. van Dam (ERIBA, University of Groningen) is thanked for assistance with a recording of ESI-MS spectra. L. Kortekaas (University of Groningen) is acknowledged for discussion. This work was performed in the framework of the COST action CM1305 “Explicit Control Over Spin-states in Technology and Biochemistry (ECOSTBio)” (with support of an STSM to W.R.B., COST-STSM-CM1305-29045)
- Subjects :
- Polimerització
Inorganic chemistry
010402 general chemistry
01 natural sciences
Redox
Polymerization
Reaccions químiques
Catalysis
Inorganic Chemistry
chemistry.chemical_compound
Transition metal
CHEMISTRY
Chemical reactions
Polymer chemistry
GALACTOSE-OXIDASE
Physical and Theoretical Chemistry
SPECTROSCOPY
010405 organic chemistry
Chemistry
Ligand
CATALYSIS
Aryl
Non-innocent ligand
0104 chemical sciences
MODEL
ACTIVE LIGANDS
Monomer
HYDROGEN-ATOM ABSTRACTION
METAL-COMPLEXES
PHENOXYL RADICAL COMPLEXES
ANODIC-OXIDATION
Subjects
Details
- Language :
- English
- ISSN :
- 00201669
- Volume :
- 56
- Issue :
- 1
- Database :
- OpenAIRE
- Journal :
- Inorganic Chemistry
- Accession number :
- edsair.doi.dedup.....6404fdd9aa1a5cad20f7fb026a425af7