Nonheme Fe(IV) Oxo Complexes of Two New Pentadentate Ligands and Their Hydrogen-Atom and Oxygen-Atom Transfer Reactions
dc.contributor.author
dc.date.accessioned
2016-03-17T09:24:56Z
dc.date.available
2016-03-17T09:24:56Z
dc.date.issued
2015
dc.identifier.issn
0020-1669
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dc.description.abstract
Two new pentadentate {N5} donor ligands based on the N4Py (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine) framework have been synthesized, viz. [N-(1-methyl-2-benzimidazolyl)methyl-N-(2-pyridyl)methyl-N-(bis-2-pyridyl methyl)amine] (L1) and [N-bis(1-methyl-2-benzimidazolyl)methyl-N-(bis-2-pyridylmethyl)amine] (L2), where one or two pyridyl arms of N4Py have been replaced by corresponding (N-methyl)benzimidazolyl-containing arms. The complexes [FeII(CH3CN)(L)]2+ (L = L1 (1); L2 (2)) were synthesized, and reaction of these ferrous complexes with iodosylbenzene led to the formation of the ferryl complexes [FeIV(O)(L)]2+ (L = L1 (3); L2 (4)), which were characterized by UV–vis spectroscopy, high resolution mass spectrometry, and Mössbauer spectroscopy. Complexes 3 and 4 are relatively stable with half-lives at room temperature of 40 h (L = L1) and 2.5 h (L = L2). The redox potentials of 1 and 2, as well as the visible spectra of 3 and 4, indicate that the ligand field weakens as ligand pyridyl substituents are progressively substituted by (N-methyl)benzimidazolyl moieties. The reactivities of 3 and 4 in hydrogen-atom transfer (HAT) and oxygen-atom transfer (OAT) reactions show that both complexes exhibit enhanced reactivities when compared to the analogous N4Py complex ([FeIV(O)(N4Py)]2+), and that the normalized HAT rates increase by approximately 1 order of magnitude for each replacement of a pyridyl moiety; i.e., [FeIV(O)(L2)]2+ exhibits the highest rates. The second-order HAT rate constants can be directly related to the substrate C–H bond dissociation energies. Computational modeling of the HAT reactions indicates that the reaction proceeds via a high spin transition state
dc.description.sponsorship
This research has been carried out within the framework of the International Research Training Group Metal Sites in Biomolecules: Structures, Regulation and Mechanisms (www.biometals.eu) and has also been supported by COST Action CM1003. M.M. thanks the European Union for an Erasmus Mundus fellowship. M.G.R. thanks the Robert A. Welch Foundation (Grant B-1093) and the Wenner−Gren Foundation for financial support and acknowledges computational resources through UNT’s High Performance Computing Services funded by NSF (CHE-0741936)
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application/pdf
dc.language.iso
eng
dc.publisher
American Chemical Society (ACS)
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Reproducció digital del document publicat a: http://dx.doi.org/10.1021/ic5029564
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© Inorganic Chemistry, 2015, vol. 54, núm. 15, p. 7152-7164
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dc.title
Nonheme Fe(IV) Oxo Complexes of Two New Pentadentate Ligands and Their Hydrogen-Atom and Oxygen-Atom Transfer Reactions
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info:eu-repo/semantics/article
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info:eu-repo/semantics/embargoedAccess
dc.embargo.terms
Cap
dc.date.embargoEndDate
info:eu-repo/date/embargoEnd/2026-01-01
dc.relation.projectID
info:eu-repo/grantAgreement/EC/FP7/239910/EU/Bio-inspired Design of Catalysts for Selective Oxidations of C-H and C=C Bonds/BIDECASEOX
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info:eu-repo/semantics/publishedVersion
dc.identifier.doi
dc.relation.FundingProgramme
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dc.identifier.eissn
1520-510X