scholarly journals Air-stable 18-electron adducts of Schrock catalysts with tuned stability constants for spontaneous release of the active species

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Henrik Gulyás ◽  
Shigetaka Hayano ◽  
Ádám Madarász ◽  
Imre Pápai ◽  
Márk Szabó ◽  
...  
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Stability Constants ◽  
Lewis Acid ◽  
Olefin Metathesis ◽  
Acid Treatment ◽  
Active Species ◽  
Activation Process ◽  
Spontaneous Release ◽  
Metathesis Catalysts

AbstractSchrock alkylidenes are highly versatile, very active olefin metathesis catalysts, but their pronounced sensitivity to air still hinders their applications. Converting them into more robust but inactive 18-electron adducts was suggested previously to facilitate their handling. Generating the active species from the inactive adducts, however, required a high-temperature Lewis acid treatment and resulted in an insoluble by-product, limiting the practicality of the methodology. Herein, we introduce an approach to circumvent the inconvenient, costly, and environmentally taxing activation process. We show that 18-electron adducts of W- and Mo-based Schrock catalysts with finite stability constants (typically K = 200–15,000 M−1) can readily be prepared and isolated in excellent yields. The adducts display enhanced air-stability in the solid state, and in solution they dissociate spontaneously, hence liberating the active alkylidenes without chemical assistance.

Aromatic radical-ion formation using lewis acid catalysts

1967 ◽  
Vol 20 (9) ◽  
pp. 1865 ◽  
Author(s):  
JL Garnett ◽  
A Rainis ◽  
WA Sollich-Baumgartner
Keyword(s):  
Solid State ◽  
Lewis Acid ◽  
Hydrogen Exchange ◽  
Active Species ◽  
Acid Catalysts ◽  
Radical Ions ◽  
Lewis Acid Catalysts ◽  
Metal Chlorides ◽  
Factors Affecting ◽  
Polycyclic Aromatic

The formation of radical ions from interactions between organic compounds with transition metal chlorides (Pt, Pd, Rh, Ru, Ir), their potassium salts, and other Lewis acid catalysts has been studied by electron spin resonance. The possible importance of these e.s.r. active species in catalytic reactions such as self-activation in isotopic hydrogen exchange and Friedel-Crafts processes has been investigated. A number of organic donors have been examined including polycyclic aromatic hydrocarbons, aromatic mines, alkenes, chloropromazine, and phenothiazine. Effect of water of crystallization, oxygen, ultraviolet radiation, and methyl substituents on the e.s.r. has been evaluated. A study has been made of the factors affecting the formation of these e.s.r. species in solution when compared with solid state interactions using as acceptors iodine, and the halides of iron, cadmium, boron, tellurium, and titanium. The results have been interpreted in terms of the formation of radical ions. It is proposed that in the solid state, the transferred electrons are weakly coupled as in a diradicaloid triplet state.

Catalytic Carbonyl-Olefin Metathesis of Aliphatic Ketones: Iron(III) HomoDimers as Lewis Acidic Superelectrophiles

2018 ◽  
Author(s):  
Haley Albright ◽  
Paul S. Riehl ◽  
Christopher C. McAtee ◽  
Jolene P. Reid ◽  
Jacob R. Ludwig ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Acid Activation ◽  
Lewis Acid Catalysts ◽  
Distinct Mode ◽  
Aliphatic Ketones ◽  
Carbon Carbon Bond ◽  
Metathesis Reactions ◽  
Acid Catalyzed

<div>Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond</div><div>formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly-bridged iron(III)-dimer as the active catalytic species. These “superelectrophiles” function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of “superelectrophiles” and broaden the current scope of catalytic carbonyl-olefin metathesis reactions.</div>

Solid-state reaction of niobium with diamond carbon at high pressure and high temperature to form superconducting composite

2021 ◽  
Vol 31 (3) ◽  
pp. 415-418
Author(s):  
Vladimir Yu. Osipov ◽  
Fedor M. Shakhov ◽  
Nikolai M. Romanov ◽  
Kazuyuki Takai
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Solid State ◽  
Solid State Reaction

A safeguarding and high temperature tolerant organogel electrolyte for flexible solid-state supercapacitors

2021 ◽  
Vol 505 ◽  
pp. 230083
Author(s):  
Yuxuan Wu ◽  
Sheng Wang ◽  
Min Sang ◽  
Quan Shu ◽  
Junshuo Zhang ◽  
...  
Keyword(s):  
High Temperature ◽  
Solid State

Activated Hoveyda‐Grubbs Olefin Metathesis Catalysts Derived from a Large Scale Produced Pharmaceutical Intermediate—Sildenafil Aldehyde

2021 ◽  
Author(s):  
Louis Monsigny ◽  
Jakub Piątkowski ◽  
Damian Trzybiński ◽  
Krzysztof Wozniak ◽  
Tomasz Nienałtowski ◽  
...  
Keyword(s):  
Olefin Metathesis ◽  
Large Scale ◽  
Metathesis Catalysts

scholarly journals HKUST-1@IL-Li Solid-state Electrolyte with 3D Ionic Channels and Enhanced Fast Li+ Transport for Lithium Metal Batteries at High Temperature

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 736
Author(s):  
Man Li ◽  
Tao Chen ◽  
Seunghyun Song ◽  
Yang Li ◽  
Joonho Bae
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Solid Electrolyte ◽  
Metal Organic Framework ◽  
Ionic Channels ◽  
Transference Numbers ◽  
Lithium Metal ◽  
Lithium Metal Batteries ◽  
Metal Organic ◽  
Organic Framework

The challenge of safety problems in lithium batteries caused by conventional electrolytes at high temperatures is addressed in this study. A novel solid electrolyte (HKUST-1@IL-Li) was fabricated by immobilizing ionic liquid ([EMIM][TFSI]) in the nanopores of a HKUST-1 metal–organic framework. 3D angstrom-level ionic channels of the metal–organic framework (MOF) host were used to restrict electrolyte anions and acted as “highways” for fast Li+ transport. In addition, lower interfacial resistance between HKUST-1@IL-Li and electrodes was achieved by a wetted contact through open tunnels at the atomic scale. Excellent high thermal stability up to 300 °C and electrochemical properties are observed, including ionic conductivities and Li+ transference numbers of 0.68 × 10-4 S·cm-1 and 0.46, respectively, at 25 °C, and 6.85 × 10-4 S·cm-1 and 0.68, respectively, at 100 °C. A stable Li metal plating/stripping process was observed at 100 °C, suggesting an effectively suppressed growth of Li dendrites. The as-fabricated LiFePO4/HKUST-1@IL-Li/Li solid-state battery exhibits remarkable performance at high temperature with an initial discharge capacity of 144 mAh g-1 at 0.5 C and a high capacity retention of 92% after 100 cycles. Thus, the solid electrolyte in this study demonstrates promising applicability in lithium metal batteries with high performance under extreme thermal environmental conditions.

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