Manganese(III) Nitrate Complexes as Bench-Stable Powerful Oxidants

We report herein a convenient one-pot synthesis for the shelf-stable molecular complex [Mn(NO3)3(OPPh3)2] (2) and describe the properties that make it a powerful and selective one-electron oxidation (deelectronation) reagent. 2 has a high reduction potential of 1.02 V versus ferrocene (MeCN) (1.65 vs normal hydrogen electrode), which is one the highest known among readily available redox agents used in chemical synthesis. 2 exhibits stability toward air in the solid state, can be handled with relative ease, and is soluble in most common laboratory solvents such as MeCN, dichloromethane, and fluorobenzene. 2 is substitutionally labile with respect to the coordinated (pseudo)halide ions enabling the synthesis of other new Mn(III) nitrato complexes also with high reduction potentials ranging from 0.6 to 1.0 V versus ferrocene

Diastereo- and Enantioselective Formal [3 + 2] Cycloaddition of Cyclopropyl Ketones and Alkenes via Ti-Catalyzed Radical Redox Relay

We report a stereoselective formal [3 + 2] cycloaddition of cyclopropyl ketones and radical-acceptor alkenes to form polysubstituted cyclopentane derivatives. Catalyzed by a chiral Ti­(salen) complex, the cycloaddition occurs via a radical redox-relay mechanism and constructs two C–C bonds and two contiguous stereogenic centers with generally excellent diastereo- and enantioselectivity

Diastereo- and Enantioselective Formal [3 + 2] Cycloaddition of Cyclopropyl Ketones and Alkenes via Ti-Catalyzed Radical Redox Relay

We report a stereoselective formal [3 + 2] cycloaddition of cyclopropyl ketones and radical-acceptor alkenes to form polysubstituted cyclopentane derivatives. Catalyzed by a chiral Ti­(salen) complex, the cycloaddition occurs via a radical redox-relay mechanism and constructs two C–C bonds and two contiguous stereogenic centers with generally excellent diastereo- and enantioselectivity

Diastereo- and Enantioselective Formal [3 + 2] Cycloaddition of Cyclopropyl Ketones and Alkenes via Ti-Catalyzed Radical Redox Relay

We report a stereoselective formal [3 + 2] cycloaddition of cyclopropyl ketones and radical-acceptor alkenes to form polysubstituted cyclopentane derivatives. Catalyzed by a chiral Ti­(salen) complex, the cycloaddition occurs via a radical redox-relay mechanism and constructs two C–C bonds and two contiguous stereogenic centers with generally excellent diastereo- and enantioselectivity

Ligand-Sensitive But Not Ligand-Diagnostic: Evaluating Cr Valence-to-Core X‑ray Emission Spectroscopy as a Probe of Inner-Sphere Coordination

This paper explores the strengths and limitations of valence-to-core X-ray emission spectroscopy (V2C XES) as a probe of coordination environments. A library was assembled from spectra obtained for 12 diverse Cr complexes and used to calibrate density functional theory (DFT) calculations of V2C XES band energies. A functional dependence study was undertaken to benchmark predictive accuracy. All 7 functionals tested reproduce experimental V2C XES energies with an accuracy of 0.5 eV. Experimentally calibrated, DFT calculated V2C XES spectra of 90 Cr compounds were used to produce a quantitative spectrochemical series showing the V2C XES band energy ranges for ligands comprising 18 distinct classes. Substantial overlaps are detected in these ranges, which complicates the use of V2C XES to identify ligands in the coordination spheres of unknown Cr compounds. The ligand-dependent origins of V2C intensity are explored for a homologous series of [Cr^III(NH₃)₅X]²⁺ (X = F, Cl, Br, and I) to rationalize the variable intensity contributions of these ligand classes

Spectroscopic Evidence for a 3d¹⁰ Ground State Electronic Configuration and Ligand Field Inversion in [Cu(CF₃)₄]^1–

The contested electronic structure of [Cu­(CF₃)₄]^1– is investigated with UV/visible/near IR spectroscopy, Cu K-edge X-ray absorption spectroscopy, and 1s2p resonant inelastic X-ray scattering. These data, supported by density functional theory, multiplet theory, and multireference calculations, support a ground state electronic configuration in which the lowest unoccupied orbital is of predominantly trifluoromethyl character. The consensus 3d¹⁰ configuration features an inverted ligand field in which all five metal-localized molecular orbitals are located at lower energy relative to the trifluoromethyl-centered σ orbitals

Rare Examples of Fe(IV) Alkyl-Imide Migratory Insertions: Impact of FeC Covalency in (Me₂IPr)Fe(NAd)R₂ (R = ^neoPe, 1‑nor)

The iron­(IV) imide complexes, (Me₂IPr)–R₂Fe=NAd (R = ^neoPe (<b>3a</b>), 1-nor (<b>3b</b>)) undergo migratory insertion to iron­(II) amides (Me₂IPr)­RFe­{NR­(Ad)} (R = ^neoPe (<b>4a</b>), 1-nor (<b>4b</b>)) without evidence of imidyl or free nitrene character. By increasing the field strength about iron, odd-electron reactivity was circumvented via increased covalency

Radical Redox-Relay Catalysis: Formal [3+2] Cycloaddition of <i>N</i>‑Acylaziridines and Alkenes

We report Ti-catalyzed radical formal [3+2] cycloadditions of <i>N</i>-acylaziridines and alkenes. This method provides an efficient approach to the synthesis of pyrrolidines, structural units prevalent in bioactive compounds and organocatalysts, from readily available starting materials. The overall redox-neutral reaction was achieved via a redox-relay mechanism, which harnesses radical intermediates for selective CN bond cleavage and formation

Chain-Straightening Polymerization of Olefins to Form Polar Functionalized Semicrystalline Polyethylene

We report the design and synthesis of an α-diimine PdII catalyst that copolymerizes functionalized and long chain α-olefins to produce semicrystalline polyethylene materials. Through a chain-straightening polymerization mechanism, the catalyst afforded high-melting point polymers with Tm values of up to 120 °C. The chain-straightening polymerization operates with high [ω,1]-insertion selectivity at high alkene concentrations and with varying α-olefin chain lengths, including propylene. The Pd catalyst can copolymerize 1-decene and methyl decenoate into semicrystalline ester-functionalized polymers with incorporation percentages proportional to the comonomer ratio (up to 13 mol %). 13C nuclear magnetic resonance and isotope labeling studies revealed that the improved selectivity relative to those of other systems arises from a high selectivity for [2,1]-insertion (96%) coupled with rapid chain-walking for a total of 90 mol % of 1-decene undergoing net [10,1]-insertion

Synthetic Methods for the Preparation of a Functional Analogue of Ru360, a Potent Inhibitor of Mitochondrial Calcium Uptake

The mixed-valent oxo-bridged ruthenium complex [(HCO₂)­(NH₃)₄Ru­(μ-O)­Ru­(NH₃)₄(O₂CH)]³⁺, known as Ru360, is a selective inhibitor of mitochondrial calcium uptake. Although this compound is useful for studying the role of mitochondrial calcium in biological processes, its widespread availability is limited because of challenges in purification and characterization. Here, we describe our investigations of three different synthetic methods for the preparation of a functional analogue of this valuable compound. We demonstrate that this analogue, isolated from our procedures, exhibits potent mitochondrial calcium uptake inhibitory properties in permeabilized HeLa cells and in isolated mitochondria