Trapping a Highly Reactive Nonheme Iron Intermediate That Oxygenates Strong C—H Bonds with Stereoretention
An unprecedentedly reactive iron species (2) has been generated by reaction of excess peracetic acid with a mononuclear iron complex [FeII(CF3SO3)2(PyNMe3)] (1) at cryogenic temperatures, and characterized spectroscopically. Compound 2 is kinetically competent for breaking strong C-H bonds of alkanes (BDE ≈ 100 kcal·mol-1) through a hydrogen-atom transfer mechanism, and the transformations proceed with stereoretention and regioselectively, responding to bond strength, as well as to steric and polar effects. Bimolecular reaction rates are at least an order of magnitude faster than those of the most reactive synthetic high-valent nonheme oxoiron species described to date. EPR studies in tande…
Exceedingly Fast Oxygen Atom Transfer to Olefins via a Catalytically Competent Nonheme Iron Species
El mateix article està publicat en alemany a l'edició alemanya d' 'Angewandte Chemie' (ISSN 0044-8249, EISSN 1521-3757), 2016, vol. 128, núm. 21, p.6418–6422. DOI http://dx.doi.org/10.1002/ange.201601396 The reaction of [Fe(CF3SO3)2(PyNMe3)] with excess peracetic acid at −40 °C leads to the accumulation of a metastable compound that exists as a pair of electromeric species, [FeIII(OOAc)(PyNMe3)]2+ and [FeV(O)(OAc)(PyNMe3)]2+, in fast equilibrium. Stopped-flow UV/Vis analysis confirmed that oxygen atom transfer (OAT) from these electromeric species to olefinic substrates is exceedingly fast, forming epoxides with stereoretention. The impact of the electronic and steric properties of the subs…
Evidence that steric factors modulate reactivity of tautomeric iron-oxo species in stereospecific alkane C-H hydroxylation
A new iron complex mediates stereospecific hydroxylation of alkyl C-H bonds with hydrogen peroxide, exhibiting excellent efficiency. Isotope labelling studies provide evidence that the relative reactivity of tautomerically related oxo-iron species responsible for the C-H hydroxylation reaction is dominated by steric factors This work has been supported by the European Union (the Erasmus Mundus program), the International Research Training Group Metal Sites in Biomolecules: Structures, Regulation and Mechanisms (www.biometals.eu), and COST Action CM1003. M.C. acknowledges ERC-29910, MINECO of Spain for CTQ2012- 37420-C02-01/BQU and CSD2010-00065, catalan DIUE (2009SGR637) and an ICREA academ…
Characterization of a Ferryl Flip in Electronically Tuned Nonheme Complexes. Consequences in Hydrogen Atom Transfer Reactivity
Two oxoiron(IV) isomers (R2a and R2b) of general formula [FeIV(O)(RPyNMe3)(CH3CN)]2+ are obtained by reaction of their iron(II) precursor with NBu4IO4. The two isomers differ in the position of the oxo ligand, cis and trans to the pyridine donor. The mechanism of isomerization between R2a and R2b has been determined by kinetic and computational analyses uncovering an unprecedented path for interconversion of geometrical oxoiron(IV) isomers. The activity of the two oxoiron(IV) isomers in hydrogen atom transfer (HAT) reactions shows that R2a reacts one order of magnitude faster than R2b, which is explained by a repulsive noncovalent interaction between the ligand and the substrate in R2b. Int…
Spectroscopic and DFT Characterization of a Highly Reactive Nonheme FeV–Oxo Intermediate
The reaction of [(PyNMe3)FeII(CF3SO3)2], 1, with excess peracetic acid at −40 °C generates a highly reactive intermediate, 2b(PAA), that has the fastest rate to date for oxidizing cyclohexane by a nonheme iron species. It exhibits an intense 490 nm chromophore associated with an S = 1/2 EPR signal having g-values at 2.07, 2.01, and 1.94. This species was shown to be in a fast equilibrium with a second S = 1/2 species, 2a(PAA), assigned to a low-spin acylperoxoiron(III) center. Unfortunately, contaminants accompanying the 2(PAA) samples prevented determination of the iron oxidation state by Mossbauer spectroscopy. Use of MeO-PyNMe3 (an electron-enriched version of PyNMe3) and cyclohexyl pero…
Triggering the generation of an iron(IV)-oxo compound and its reactivity toward sulfides by RuII photocatalysis
The preparation of [FeIV(O)(MePy2tacn)]2+ (2, MePy2tacn = N-methyl-N,N-bis(2-picolyl)-1,4,7-triazacyclononane) by reaction of [FeII(MePy2tacn)(solvent)]2+ (1) and PhIO in CH3CN and its full characterization are described. This compound can also be prepared photochemically from its iron(II) precursor by irradiation at 447 nm in the presence of catalytic amounts of [Ru II(bpy)3]2+ as photosensitizer and a sacrificial electron acceptor (Na2S2O8). Remarkably, the rate of the reaction of the photochemically prepared compound 2 toward sulfides increases 150-fold under irradiation, and 2 is partially regenerated after the sulfide has been consumed; hence, the process can be repeated several times.…
CCDC 1418388: Experimental Crystal Structure Determination
Related Article: Mainak Mitra , Hassan Nimir , Serhiy Demeshko , Satish S. Bhat , Sergey O. Malinkin , Matti Haukka , Julio Lloret-Fillol , George C. Lisensky , Franc Meyer , Albert A. Shteinman , Wesley R. Browne , David A. Hrovat , Michael G.Richmond , Miquel Costas , Ebbe Nordlander|2015|Inorg.Chem.|54|7152|doi:10.1021/ic5029564
CCDC 960139: Experimental Crystal Structure Determination
Related Article: Mainak Mitra, Julio Lloret-Fillol, Matti Haukka, Miquel Costas, Ebbe Nordlander|2014|Chem.Commun.|50|1408|doi:10.1039/C3CC47830K
CCDC 1033835: Experimental Crystal Structure Determination
Related Article: Mainak Mitra , Hassan Nimir , Serhiy Demeshko , Satish S. Bhat , Sergey O. Malinkin , Matti Haukka , Julio Lloret-Fillol , George C. Lisensky , Franc Meyer , Albert A. Shteinman , Wesley R. Browne , David A. Hrovat , Michael G.Richmond , Miquel Costas , Ebbe Nordlander|2015|Inorg.Chem.|54|7152|doi:10.1021/ic5029564
CCDC 2192965: Experimental Crystal Structure Determination
Related Article: Valeria Dantignana, M. Carmen Pérez-Segura, Pau Besalú-Sala, Estefanía Delgado-Pinar, Álvaro Martínez-Camarena, Joan Serrano-Plana, Andrea Álvarez-Núñez, Carmen E. Castillo, Enrique García-España, Josep M. Luis, Manuel G. Basallote, Miquel Costas, Anna Company|2023|Angew.Chem.,Int.Ed.|62||doi:10.1002/anie.202211361
CCDC 2192964: Experimental Crystal Structure Determination
Related Article: Valeria Dantignana, M. Carmen Pérez-Segura, Pau Besalú-Sala, Estefanía Delgado-Pinar, Álvaro Martínez-Camarena, Joan Serrano-Plana, Andrea Álvarez-Núñez, Carmen E. Castillo, Enrique García-España, Josep M. Luis, Manuel G. Basallote, Miquel Costas, Anna Company|2023|Angew.Chem.,Int.Ed.|62||doi:10.1002/anie.202211361
CCDC 1840192: Experimental Crystal Structure Determination
Related Article: Ruixi Fan, Joan Serrano-Plana, Williamson N. Oloo, Apparao Draksharapu, Estefanía Delgado-Pinar, Anna Company, Vlad Martin-Diaconescu, Margarida Borrell, Julio Lloret-Fillol, Enrique García-España, Yisong Guo, Emile L. Bominaar, Lawrence Que Junior, Miquel Costas, Eckard Münck|2018|J.Am.Chem.Soc.|140|3916|doi:10.1021/jacs.7b11400
CCDC 1036385: Experimental Crystal Structure Determination
Related Article: Joan Serrano-Plana, Williamson N. Oloo, Laura Acosta-Rueda, Katlyn K. Meier, Begoña Verdejo, Enrique García-España, Manuel G. Basallote, Eckard Münck, Lawrence Que Junior, Anna Company, and Miquel Costas|2015|J.Am.Chem.Soc.|137|15833|doi:10.1021/jacs.5b09904
CCDC 1003098: Experimental Crystal Structure Determination
Related Article: Anna Company , Gerard Sabenya , María González-Béjar , Laura Gómez , Martin Clémancey , Geneviève Blondin , Andrew J. Jasniewski , Mayank Puri , Wesley R. Browne , Jean-Marc Latour , Lawrence Que Junior, Miquel Costas , Julia Pérez-Prieto, and Julio Lloret-Fillol|2014|J.Am.Chem.Soc.|136|4624|doi:10.1021/ja412059c
CCDC 2192963: Experimental Crystal Structure Determination
Related Article: Valeria Dantignana, M. Carmen Pérez-Segura, Pau Besalú-Sala, Estefanía Delgado-Pinar, Álvaro Martínez-Camarena, Joan Serrano-Plana, Andrea Álvarez-Núñez, Carmen E. Castillo, Enrique García-España, Josep M. Luis, Manuel G. Basallote, Miquel Costas, Anna Company|2023|Angew.Chem.,Int.Ed.|62||doi:10.1002/anie.202211361
CCDC 1446018: Experimental Crystal Structure Determination
Related Article: Joan Serrano-Plana, Williamson N. Oloo, Laura Acosta-Rueda, Katlyn K. Meier, Begoña Verdejo, Enrique García-España, Manuel G. Basallote, Eckard Münck, Lawrence Que Junior, Anna Company, and Miquel Costas|2015|J.Am.Chem.Soc.|137|15833|doi:10.1021/jacs.5b09904
CCDC 960138: Experimental Crystal Structure Determination
Related Article: Mainak Mitra, Julio Lloret-Fillol, Matti Haukka, Miquel Costas, Ebbe Nordlander|2014|Chem.Commun.|50|1408|doi:10.1039/C3CC47830K
CCDC 2192962: Experimental Crystal Structure Determination
Related Article: Valeria Dantignana, M. Carmen Pérez-Segura, Pau Besalú-Sala, Estefanía Delgado-Pinar, Álvaro Martínez-Camarena, Joan Serrano-Plana, Andrea Álvarez-Núñez, Carmen E. Castillo, Enrique García-España, Josep M. Luis, Manuel G. Basallote, Miquel Costas, Anna Company|2023|Angew.Chem.,Int.Ed.|62||doi:10.1002/anie.202211361
CCDC 994961: Experimental Crystal Structure Determination
Related Article: Mainak Mitra , Hassan Nimir , Serhiy Demeshko , Satish S. Bhat , Sergey O. Malinkin , Matti Haukka , Julio Lloret-Fillol , George C. Lisensky , Franc Meyer , Albert A. Shteinman , Wesley R. Browne , David A. Hrovat , Michael G.Richmond , Miquel Costas , Ebbe Nordlander|2015|Inorg.Chem.|54|7152|doi:10.1021/ic5029564