Cobalt-Catalyzed Intramolecular Oxidative C(sp³)–H/N–H Carbonylation of Aliphatic Amides

A cobalt-catalyzed reaction protocol is developed to achieve the intramolecular oxidative C­(sp³)–H/N–H carbonylation of aliphatic amides with CO. Various substituted propanamides are selectively transformed into corresponding succinimides in good to high yields. Notably, predominant selectivity for the carbonylation at the α-methyl groups of linear aliphatic amides is observed in this reaction system

Electronic Structure and Transformation of Dinitrosyl Iron Complexes (DNICs) Regulated by Redox Non-Innocent Imino-Substituted Phenoxide Ligand

The coupled NO-vibrational peaks [IR νNO 1775 s, 1716 vs, 1668 vs cm–1 (THF)] between two adjacent [Fe(NO)2] groups implicate the electron delocalization nature of the singly O-phenoxide-bridged dinuclear dinitrosyliron complex (DNIC) [Fe(NO)2(μ-ON2Me)Fe(NO)2] (1). Electronic interplay between [Fe(NO)2] units and [ON2Me]− ligand in DNIC 1 rationalizes that “hard” O-phenoxide moiety polarizes iron center(s) of [Fe(NO)2] unit(s) to enforce a “constrained” π-conjugation system acting as an electron reservoir to bestow the spin-frustrated {Fe(NO)2}9-{Fe(NO)2}9-[·ON2Me]2– electron configuration (Stotal = 1/2). This system plays a crucial role in facilitating the ligand-based redox interconversion, working in harmony to control the storage and redox-triggered transport of the [Fe(NO)2]10 unit, while preserving the {Fe(NO)2}9 core in DNICs {Fe(NO)2}9-[·ON2Me]2– [K-18-crown-6-ether)][(ON2Me)Fe(NO)2] (2) and {Fe(NO)2}9-[·ON2Me] [(ON2Me)Fe(NO)2][PF6] (3). Electrochemical studies suggest that the redox interconversion among [{Fe(NO)2}9-[·ON2Me]2–] DNIC 3 ↔ [{Fe(NO)2}9-[ON2Me]−] ↔ [{Fe(NO)2}9-[·ON2Me]] DNIC 2 are kinetically feasible, corroborated by the redox shuttle between O-bridged dimerized [(μ-ONMe)2Fe2(NO)4] (4) and [K-18-crown-6-ether)][(ONMe)Fe(NO)2] (5). In parallel with this finding, the electronic structures of [{Fe(NO)2}9-{Fe(NO)2}9-[·ON2Me]2–] DNIC 1, [{Fe(NO)2}9-[·ON2Me]2–] DNIC 2, [{Fe(NO)2}9-[·ON2Me]] DNIC 3, [{Fe(NO)2}9-[ONMe]−]2 DNIC 4, and [{Fe(NO)2}9-[·ONMe]2–] DNIC 5 are evidenced by EPR, SQUID, and Fe K-edge pre-edge analyses, respectively

X-ray Absorption Spectroscopic Study on Interfacial Electronic Properties of FeOOH/Reduced Graphene Oxide for Asymmetric Supercapacitors

[[abstract]]The effects of growth time and interface between the iron oxyhydroxide (FeOOH) and carbon materials (carbon nanotubes (CNT) and reduced graphene oxide (RGO)) to form an asymmetric supercapacitor was studied by X-ray absorption spectroscopy (XAS) and electrochemical measurements. FeOOH/CNT (FCNT) and FeOOH/RGO (FRGO) were successfully synthesized by a simple spontaneous redox reaction with FeCl3. The RGO functions as an ideal substrate, providing rich growth sites for FeOOH, and it is believed to facilitate the transport of electrons/ions across the electrode/electrolyte interface. FRGO has been identified as a supercapacitor and found to exhibit significantly greater capacitance than FCNT. To gain further insight into the effects of growth times and the interface of FeOOH for FCNT and FRGO, the electronic structures of FCNT and FRGO with various FeOOH growth times were elucidated by XAS. The difference between the surface electronic structures of CNT and RGO yields different nucleation and growth rates of FeOOH of FeOOH. RGO with excellent interface properties arises from a high degree of covalent functionalization, and/or defects make it favorable for FeOOH growth. FRGO is therefore a promising electrode material for use in the fabrication of asymmetric supercapacitors. In this work, coupled XAS and electrochemical measurements reveal the electronic structure of the interface between FeOOH and the carbon materials and the capacitance performance of asymmetric supercapacitors, which are very useful in the fields of nanomaterials and nanotechnology, especially for their applications in storing energy[[notice]]補正完

Cobalt-Catalyzed Electrochemical Oxidative C–H/N–H Carbonylation with Hydrogen Evolution

Carbon monoxide is an abundant and cost-efficient C1 building block for the carbonylation industry. Transition-metal-catalyzed oxidative C–H/C­(X)–H carbonylation with CO provides one of the most straightforward approaches to construct carbonyl compounds. However, the use of stoichiometric oxidants would bring several drawbacks such as high cost and undesired chemical waste. Especially, the explosion limit is a potential safety hazard in oxidative carbonylation using O₂ as the oxidant. To overcome these issues, an electrochemical strategy for oxidative C–H/N–H carbonylation has been designed by taking advantage of anodic oxidation to recycle a cobalt catalyst, and H₂ is generated at the cathode. The intra- and intermolecular carbonylation products can be achieved with good functional group tolerance in 31%–99% yields. A plausible reaction mechanism involving a Co^II/Co^III/Co^I catalytic cycle is proposed by the studies of XANES and CV

X‑ray Absorption and Electron Paramagnetic Resonance Guided Discovery of the Cu-Catalyzed Synthesis of Multiaryl-Substituted Furans from Aryl Styrene and Ketones Using DMSO as the Oxidant

The first example of DMSO serving not only as a solvent but also as an oxidant to promote the oxidation of Cu­(I) to Cu­(II) has been demonstrated. X-ray absorption and electron paramagnetic resonance evidence revealed a single-electron redox process where DMSO could oxidize Cu­(I) to Cu­(II). The novel discovery guided the rational design of copper-catalyzed oxidative cyclization of aryl ketones with styrenes to furans, providing a new method for the synthesis of multiaryl-substituted furans from cheap and readily available starting materials