Non-heme iron oxygenases utilize dioxygen to accomplish challenging chemical oxidations. Further understanding of the Fe-O2 intermediates implicated in these processes is challenged by their highly transient nature. To that end, we have developed a ligand platform featuring phosphinimide donors intended to stabilize oxidized, high-spin iron complexes. O2 exposure of single crystals of a threecoordinate Fe(II) complex of this framework allowed for in crystallo trapping of a terminally-bound Fe-O2 complex suitable for XRD characterization. Spectroscopic and computational studies of this species support a high-spin Fe(III) center antiferromagnetically coupled to a superoxide ligand, similar to that proposed for numerous non-heme iron oxygenases. In addition to the stability of this synthetic Fe-O2 complex, its ability to engage in a range of stoichiometric and catalytic oxidation processes demonstrates that this iron-phosphinimide system is primed for development in modelling oxidizing bioinorganic intermediates and green oxidation chemistry.
Terminal, π-basic moieties occupy a prominent position in the stabilization of unusual or reactive inorganic species. The electron-releasing, π-basic properties of phosphinimides (PN) have been employed to stabilize electron-deficient early transition metals and lanthanides. In principle, a ligand field comprised of terminal PN groups should enable access to high-valent states of late first row transition metals. Herein, we report a new class of multidentate phosphinimide ligands to logically explore this hypothesis. Access to such ligands is made possible by a new procedure for the electrophilic amination of rigid, sterically encumbering, multidentate phosphines. Such frameworks facilitate terminal PN coordination to cobalt as demonstrated by the synthesis of a trinuclear CoII 3 complex and a homoleptic, three-coordinate CoIII complex. Interestingly, the CoIII complex exhibits an exceedingly rare S = 2 ground state. Combined XRD, magnetic susceptibility, and DFT studies highlight that terminally bound PNs engage in strong dπ–pπ interactions that present a weak ligand field appropriate to stabilize high-spin states of late transition metals.
Acid-catalyzed decomposition of dicumyl peroxide in dodecane from 60 to 130 °C produces α-methylstyrene and phenol as the major products. Pseudo-first-order rate constants were determined as a function of the temperature for the reaction of DCP with dodecylbenzenesulfonic acid in dodecane and resulted in an Arrhenius plot exhibiting two distinct kinetic regimes with differing activation energies: 76.9 kJ/mol at low temperatures (measured from 60 to 90 °C) and 8.50 kJ/mol at higher temperatures (measured from 90 to 130 °C). With employment of a combination of kinetics, product analysis, and trapping experiments, evidence is presented to show the intermediacy of cumene hydroperoxidea reactive intermediate absent from previous mechanistic descriptions of this process. The yield of cumene hydroperoxide production is discussed, and the mechanistic pathways for formation of the observed products are presented.
Terminal, π-basic moieties occupy a prominent position in the stabilization of unusual or reactive inorganic species. The electron-releasing, π-basic properties of phosphinimides have been employed to stabilize electron deficient early transition metals and lanthanides. In principle, a ligand field comprised of terminal PN groups should enable access to high-valent states of late first row transition metals. Herein, we report a new class of multidentate phosphinimide ligands to logically explore this hypothesis. Access to such ligands is made possible by a new procedure for the electrophilic amination of rigid, sterically-encumbering, multidentate phosphines. Such frameworks facilitate terminal PN coordination to Cobalt as demonstrated by the synthesis of a three-coordinate CoIII complex, which exhibits an exceedingly rare S = 2 ground state. Combined XRD, magnetic susceptibility, and DFT studies highlight that terminally-bound PNs engage in strong dπ-pπ interactions that present a weak ligand field appropriate to stabilize high-spin states of late transition metals.
Terminal, π-basic moieties occupy a prominent position in the stabilization of unusual or reactive inorganic species. The electron-releasing, π-basic properties of phosphinimides (PN) have been employed to stabilize electrondeficient early transition metals and lanthanides. In principle, a ligand field comprised of terminal PN groups should enable access to high-valent states of late first row transition metals. Herein, we report a new class of multidentate phosphinimide ligands to logically explore this hypothesis. Access to such ligands is made possible by a new procedure for the electrophilic amination of rigid, sterically-encumbering, multidentate phosphines. Such frameworks facilitate terminal PN coordination to Cobalt as demonstrated by the synthesis of a trinuclear Co II 3 complex and a homoleptic, three-coordinate Co III complex. Interestingly, the Co III complex exhibits an exceedingly rare S = 2 ground state. Combined XRD, magnetic susceptibility, and DFT studies highlight that terminally-bound PNs engage in strong dπ-pπ interactions that present a weak ligand field appropriate to stabilize high-spin states of late transition metals.the filtrate under reduced pressure. The 1 H NMR (Figure S23) matches an authentic sample of 2 (11.0 mg, 28 %). ASSOCIATED CONTENTSupporting Information. Experimental procedures and characterization. This material is available free of charge via the Internet at http://pubs.acs.org.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.