O 2 activation at nonheme iron centers is a common motif in biological systems. While synthetic models have provided numerous insights into the reactivity of high-valent iron−oxo complexes related to biological processes, the majority of these complexes are synthesized using alternative oxidants. This report describes O 2 activation by an iron(II)−triflate complex of the imino-functionalized tris(pyrrol-2-ylmethyl)amine ligand framework, H 3 [N(pi Cy ) 3 ]. Initial reaction conditions result in the formation of a mixture of oxidation products including terminal iron(III)−oxo and iron(III)−hydroxo complexes. The relevance of these species to the O 2 activation process is demonstrated through reactivity studies and electrochemical analysis of the iron(III)−oxo complex.

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Bridged μ-oxo iron porphyrins serve as photocatalysts for oxidative organic transformations, but suffer from low photon-to-product efficiency. This low photochemical quantum yield is most commonly attributed to the short lifetime...

A Co­(acac)3/PN precatalyst was developed and optimized for catalytic Kumada coupling of aryl Grignard reagents to sterically encumbered alkyl halides. The substrate scope demonstrates excellent yields for primary alkyl chlorides and bromides, including good performance using neopentyl chloride and neophyl chloride. Secondary alkyl halides were also successfully arylated in good yields, and the presence of β-hydrogen atoms in a substrate did not inhibit product formation. An intermolecular functional group tolerance screen was conducted which indicates that ester and amide functionality are well tolerated by the reaction conditions. Electrophiles containing ester, pyridine, and nitrile functionality were all coupled with 2-mesitylmagnesium bromide in good yields, supporting tolerance screen results. The intermolecular screen also showed that functional groups which are typically reactive with Grignard reagents such as alcohols and terminal alkynes were not well-tolerated by the reaction.

Femtosecond X-ray absorption spectroscopy at the Ir O3-edge and N6,7-edges is performed on the photocatalyst iridium(III) tris(2-phenylpyridine), Ir(III)(ppy)3 using a tabletop high-harmonic source. Extreme ultraviolet (XUV) absorption between 44 and 76 eV measures transitions from the Ir 5p 3/2 and 4f 5/2,7/2 core to 5d valence orbitals, and the position of these spectral features is shown to be sensitive to the oxidation state and ligand field of the metal center. Upon excitation of the singlet metal-to-ligand charge transfer (1MLCT) band at 400 nm, a shift in the spectra due to the formation of the Ir(IV) center is observed, as is the creation of a new spectral feature corresponding to transitions into the t2g hole. Vibrational cooling of the MLCT state on the 3 and 16 ps time scales is measured as changes in the intensity of the transient features. This work establishes XUV spectroscopy as a useful tool for measuring the electronic structure of third row transition metal photosensitizers and catalysts at ultrafast time scales.