Nonheme Fe(IV) Oxo Complexes of Two New Pentadentate Ligands and Their Hydrogen-Atom and Oxygen-Atom Transfer Reactions
Author | Mitra, Mainak |
Author | Nimir, Hassan |
Author | Demeshko, Serhiy |
Author | Bhat, Satish S. |
Author | Malinkin, Sergey O. |
Author | Haukka, Matti |
Author | Lloret-Fillol, Julio |
Author | Lisensky, George C. |
Author | Meyer, Franc |
Author | Shteinman, Albert A. |
Author | Browne, Wesley R. |
Author | Hrovat, David A. |
Author | Richmond, Michael G. |
Author | Costas, Miquel |
Author | Nordlander, Ebbe |
Available date | 2024-02-29T09:37:35Z |
Publication Date | 2015-07-22 |
Publication Name | Inorganic Chemistry |
Identifier | http://dx.doi.org/10.1021/ic5029564 |
Citation | Mitra, M., Nimir, H., Demeshko, S., Bhat, S. S., Malinkin, S. O., Haukka, M., ... & Nordlander, E. (2015). Nonheme Fe (IV) oxo complexes of two new pentadentate ligands and their hydrogen-atom and oxygen-atom transfer reactions. Inorganic Chemistry, 54(15), 7152-7164. |
ISSN | 0020-1669 |
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] (L<sup>1</sup>) and [N-bis(1-methyl-2-benzimidazolyl)methyl-N-(bis-2-pyridylmethyl)amine] (L<sup>2</sup>), where one or two pyridyl arms of N4Py have been replaced by corresponding (N-methyl)benzimidazolyl-containing arms. The complexes [Fe<sup>II</sup>(CH<inf>3</inf>CN)(L)]<sup>2+</sup> (L = L<sup>1</sup> (1); L<sup>2</sup> (2)) were synthesized, and reaction of these ferrous complexes with iodosylbenzene led to the formation of the ferryl complexes [Fe<sup>IV</sup>(O)(L)]<sup>2+</sup> (L = L<sup>1</sup> (3); L<sup>2</sup> (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 = L<sup>1</sup>) and 2.5 h (L = L<sup>2</sup>). 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 ([Fe<sup>IV</sup>(O)(N4Py)]<sup>2+</sup>), and that the normalized HAT rates increase by approximately 1 order of magnitude for each replacement of a pyridyl moiety; i.e., [Fe<sup>IV</sup>(O)(L<sup>2</sup>)]<sup>2+</sup> 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. |
Sponsor | This work was supported by: - European Cooperation in Science and Technology (CM1003). - National Stroke Foundation (CHE-0741936). - Wenner-Gren Foundation - Seventh Framework Programme (239910). |
Language | en |
Publisher | American Chemical Society (ACS) |
Subject | Electrochemistry Nonheme Fe(IV) |
Type | Article |
Pagination | 7152-7164 |
Issue Number | 15 |
Volume Number | 54 |
ESSN | 1520-510X |
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