Search results for: Kazunari Yoshizawa

Items from 1 to 20 out of 194 results

article

Catalytic Reduction of Dinitrogen into Ammonia and Hydrazine by Using Chromium Complexes Bearing PCP‐Type Pincer Ligands**

Yuya Ashida, Akihito Egi, Kazuya Arashiba, Hiromasa Tanaka, more

Chemistry – A European Journal > 28 > 25 > n/a - n/a

A series of chromium‐halide, ‐nitride, and ‐dinitrogen complexes bearing carbene‐ and phosphine‐based PCP‐type pincer ligands has been newly prepared, and some of them are found to work as effective catalysts to reduce dinitrogen under atmospheric pressure, whereby up to 11.60 equiv. of ammonia and 2.52 equiv. of hydrazine (16.6 equiv. of fixed N atom) are produced based on the chromium atom. To the...

article

Cover Feature: Catalytic Reduction of Dinitrogen into Ammonia and Hydrazine by Using Chromium Complexes Bearing PCP‐Type Pincer Ligands (Chem. Eur. J. 25/2022)

Yuya Ashida, Akihito Egi, Kazuya Arashiba, Hiromasa Tanaka, more

Chemistry – A European Journal > 28 > 25 > n/a - n/a

A series of chromium complexes bearing a carbene‐ and phosphine‐based PCP‐type pincer ligand has been newly prepared, and some of them are found to work as effective catalysts to reduce dinitrogen into ammonia and hydrazine under atmospheric pressure. This reaction can be expressed as nitrogen molecules (raindrops) being converted into ammonia and hydrazine on the chromium complex (umbrella). More...

article

Heterointerface Created on Au‐Cluster‐Loaded Unilamellar Hydroxide Electrocatalysts as a Highly Active Site for the Oxygen Evolution Reaction (Adv. Mater. 16/2022)

Sho Kitano, Tomohiro G. Noguchi, Masamichi Nishihara, Kazutaka Kamitani, more

Advanced Materials > 34 > 16 > n/a - n/a

Oxygen Evolution Reaction In article number 2110552, Aleksandar Staykov, Miho Yamauchi, and co‐workers report that Au‐cluster‐loaded unillamellar hydroxide catalysts drastically enhance the electrochemical oxygen evolution reaction (OER). The electronic sates of a catalytic site can be finely tuned by the formation of a Au‐cluster–hydroxide interface for the OER. Theoretical and advanced spectroscopic...

article

Heterointerface Created on Au‐Cluster‐Loaded Unilamellar Hydroxide Electrocatalysts as a Highly Active Site for the Oxygen Evolution Reaction

Sho Kitano, Tomohiro G. Noguchi, Masamichi Nishihara, Kazutaka Kamitani, more

Advanced Materials > 34 > 16 > n/a - n/a

The oxygen evolution reaction (OER) is a critical element for all sorts of reactions that use water as a hydrogen source, such as hydrogen evolution and electrochemical CO₂ reduction, and novel design principles that provide highly active sites on OER electrocatalysts push the limits of their practical applications. Herein, Au‐cluster loading on unilamellar exfoliated layered double hydroxide (ULDH)...

article

Quadruple Role of Pd Catalyst in Domino Reaction Involving Aryl to Alkyl 1,5‐Pd Migration to Access 1,9‐Bridged Triptycenes

Takayuki Iwata, Satoru Kumagai, Tatsuro Yoshinaga, Masato Hanada, more

Chemistry – A European Journal > 27 > 45 > 11548 - 11553

A Pd‐catalyzed domino reaction of 1,8,13‐tribromo‐9‐methoxytriptycenes is reported. Under conventional Suzuki coupling conditions, the triptycenes underwent multiple transformations to give 1,9‐bridged triptycenes. Based on mechanistic investigations, a single Pd catalyst functions as Pd⁰, Pd^II and Pd^IV species to catalyze four distinct processes: (1) aryl to alkyl 1,5‐Pd migration, (2) intramolecular...

article

Cover Feature: Quadruple Role of Pd Catalyst in Domino Reaction Involving Aryl to Alkyl 1,5‐Pd Migration to Access 1,9‐Bridged Triptycenes (Chem. Eur. J. 45/2021)

Takayuki Iwata, Satoru Kumagai, Tatsuro Yoshinaga, Masato Hanada, more

Chemistry – A European Journal > 27 > 45 > 11478 - 11478

A Pd‐catalyzed domino reaction of 1,8,13‐tribromo‐9‐methoxytriptycenes is reported. Under conventional Suzuki coupling conditions, the triptycenes underwent multiple transformations to give 1,9‐bridged triptycenes. Based on mechanistic investigations, a single Pd catalyst functions as Pd⁰, Pd^II and Pd^IV species to catalyze four distinct processes: 1) aryl‐to‐alkyl 1,5‐Pd migration, 2) intramolecular...

article

Ammonia Formation Catalyzed by a Dinitrogen‐Bridged Dirhenium Complex Bearing PNP‐Pincer Ligands under Mild Reaction Conditions**

Fanqiang Meng, Shogo Kuriyama, Hiromasa Tanaka, Akihito Egi, more

Angewandte Chemie > 133 > 25 > 14025 - 14031

A series of rhenium complexes bearing a pyridine‐based PNP‐type pincer ligand are synthesized from rhenium phosphine complexes as precursors. A dinitrogen‐bridged dirhenium complex bearing the PNP‐type pincer ligands catalytically converts dinitrogen into ammonia during the reaction with KC₈ as a reductant and [HPCy₃]BAr^F₄ (Cy=cyclohexyl, Ar^F=3,5‐(CF₃)₂C₆H₃) as a proton source at −78 °C to afford...

article

Ammonia Formation Catalyzed by a Dinitrogen‐Bridged Dirhenium Complex Bearing PNP‐Pincer Ligands under Mild Reaction Conditions**

Fanqiang Meng, Shogo Kuriyama, Hiromasa Tanaka, Akihito Egi, more

Angewandte Chemie International Edition > 60 > 25 > 13906 - 13912

article

Synthesis, spectral characterization, density functional theory studies, and biological screening of some transition metal complexes of a novel hydrazide–hydrazone ligand of isonicotinic acid

Dina A. Tolan, Tahani I. Kashar, Kazunari Yoshizawa, Ahmed M. El‐Nahas

Applied Organometallic Chemistry > 35 > 6 > n/a - n/a

Novel Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) complexes (1–7) of hydrazide–hydrazone ligand (H₂L) derived from the condensation of isonicotinic acid hydrazide with (Z)‐N′‐(2‐nitrobenzylidene)‐3‐oxobutanehydrazide have been prepared. The ligand and its chelates were characterized based on elemental analysis, spectral, thermal analysis, molar conductance, and magnetic moment measurements...

article

Cycling between Molybdenum‐Dinitrogen and ‐Nitride Complexes to Support the Reaction Pathway for Catalytic Formation of Ammonia from Dinitrogen

Kazuya Arashiba, Hiromasa Tanaka, Kazunari Yoshizawa, Yoshiaki Nishibayashi

Chemistry – A European Journal > 26 > 59 > 13383 - 13389

Cycling between molybdenum(I)‐dinitrogen and molybdenum(IV)‐nitride complexes was investigated under ambient reaction conditions. A kinetic study of the second‐order reaction rate for the conversion of the molybdenum‐dinitrogen complex into the molybdenum‐nitride complex indicates that the formation of the dinitrogen‐bridged dimolybdenum complex is involved in the rate‐determining step. DFT calculations...

article

Cycling between Molybdenum‐Dinitrogen and ‐Nitride Complexes to Support the Reaction Pathway for Catalytic Formation of Ammonia from Dinitrogen

Kazuya Arashiba, Hiromasa Tanaka, Kazunari Yoshizawa, Yoshiaki Nishibayashi

Chemistry – A European Journal > 26 > 59 > 13321 - 13321

Invited for the featured front cover of Kazuya Arashiba, Hiromasa Tanaka, Kazunari Yoshizawa, and Yoshiaki Nishibayashi at The University of Tokyo, Daido University, and Kyushu University. The image depicts a roulette wheel to represent the cycling reaction used in this work. Read the full text of the article at 10.1002/chem.202002200.

article

Front Cover: Cycling between Molybdenum‐Dinitrogen and ‐Nitride Complexes to Support the Reaction Pathway for Catalytic Formation of Ammonia from Dinitrogen (Chem. Eur. J. 59/2020)

Kazuya Arashiba, Hiromasa Tanaka, Kazunari Yoshizawa, Yoshiaki Nishibayashi

Chemistry – A European Journal > 26 > 59 > 13317 - 13317

Cycling between molybdenum(I)–dinitrogen and molybdenum(IV)–nitride complexes was investigated under ambient reaction conditions. Here, a new modified reaction pathway has been proposed based on the findings of experimental and theoretical results. The molecular dinitrogen (ball) on the roulette fixes as dinitrogen and nitride ligand on molybdenum complexes. The ball thrown into the roulette smoothly...

article

Three‐Step Spin State Transition and Hysteretic Proton Transfer in the Crystal of an Iron(II) Hydrazone Complex

Takumi Nakanishi, Yuta Hori, Shuqi Wu, Hiroyasu Sato, more

Angewandte Chemie > 132 > 35 > 14891 - 14897

A proton–electron coupling system, exhibiting unique bistability or multistability of the protonated state, is an attractive target for developing new switchable materials based on proton dynamics. Herein, we present an iron(II) hydrazone crystalline compound, which displays the stepwise transition and bistability of proton transfer at the crystal level. These phenomena are realized through the coupling...

article

Three‐Step Spin State Transition and Hysteretic Proton Transfer in the Crystal of an Iron(II) Hydrazone Complex

Takumi Nakanishi, Yuta Hori, Shuqi Wu, Hiroyasu Sato, more

Angewandte Chemie International Edition > 59 > 35 > 14781 - 14787

article

Anthranoxides as Highly Reactive Arynophiles for the Synthesis of Triptycenes

Takayuki Iwata, Mizuki Hyodo, Takuto Fukami, Yoshihito Shiota, more

Chemistry – A European Journal > 26 > 39 > 8506 - 8510

We report herein an efficient method to synthesize triptycenes by the reaction of benzynes and anthranoxides, which are electron‐rich and readily prepared from the corresponding anthrones. Using this method, 1,9‐syn‐substituted triptycenes were regioselectively obtained employing 3‐methoxybenzynes. This method was also applied to synthesize pentiptycenes. A DFT study revealed that the cycloaddition...

article

Cover Feature: Anthranoxides as Highly Reactive Arynophiles for the Synthesis of Triptycenes (Chem. Eur. J. 39/2020)

Takayuki Iwata, Mizuki Hyodo, Takuto Fukami, Yoshihito Shiota, more

Chemistry – A European Journal > 26 > 39 > 8479 - 8479

An efficient method to synthesize triptycenes through the reaction of benzynes and anthranoxides, which are electron‐rich and readily prepared from the corresponding anthrones, is reported. Using this method, 1,9‐syn‐substituted triptycenes were regioselectively obtained employing 3‐methoxybenzynes. This method was also applied to synthesize pentiptycenes. A DFT study revealed that the cycloaddition...

article

Mechanistic Study on Catalytic Disproportionation of Hydrazine by a Protic Pincer‐Type Iron Complex through Proton‐Coupled Electron Transfer

Hiromasa Tanaka, Seiji Hitaoka, Kazuki Umehara, Kazunari Yoshizawa, more

European Journal of Inorganic Chemistry > 2020 > 15-16 > 1472 - 1482

Density functional theory calculations have been performed for the proposal of a plausible reaction pathway for disproportionation of hydrazine catalyzed by an iron complex bearing a multiproton‐responsive pincer‐type bis(pyrazole) ligand. The pyrazole arms in this ligand are capable of serving as both Brønsted acid and base. At the first stage of the catalytic cycle, a hydrazine molecule bound to...

article

Nitrogen Fixation Catalyzed by Dinitrogen‐Bridged Dimolybdenum Complexes Bearing PCP‐ and PNP‐Type Pincer Ligands: A Shortcut Pathway Deduced from Free Energy Profiles

Akihito Egi, Hiromasa Tanaka, Asuka Konomi, Yoshiaki Nishibayashi, more

European Journal of Inorganic Chemistry > 2020 > 15-16 > 1490 - 1498

Density‐functional‐theory (DFT) calculations are carried out for the proposal of a theoretically‐plausible reaction pathway for nitrogen fixation catalyzed by dinitrogen‐bridged dimolybdenum complexes bearing pincer‐type PCP and PNP ligands. The free energy profiles of the entire reaction pathway calculated with a dispersion‐corrected functional provide a catalytic mechanism energetically more efficient...

article

Mechanistic Study on Ring‐Contracting Skeletal Rearrangement from Porphycene to Isocorrole by Experimental and Theoretical Methods

Taro Koide, Takafumi Maeda, Tsukasa Abe, Yoshihito Shiota, more

European Journal of Organic Chemistry > 2020 > 12 > 1811 - 1816

In this study, the ring contracting skeletal rearrangement reaction in one‐pot under basic conditions from octaethylporphycene to two types of isocorroles, i.e., the meso‐formyl and meso‐free forms, was confirmed and the reaction mechanism was proposed by the comparative analyses of the experimental and theoretical studies. The electron accepting nature of the porphycene and imine‐amine conversion...

article

Cover Feature: Mechanistic Study on Ring‐Contracting Skeletal Rearrangement from Porphycene to Isocorrole by Experimental and Theoretical Methods (Eur. J. Org. Chem. 12/2020)

Taro Koide, Takafumi Maeda, Tsukasa Abe, Yoshihito Shiota, more

European Journal of Organic Chemistry > 2020 > 12 > 1783 - 1783

The Cover Feature shows the rings as the background since this study is on the ring contraction of macrocyclic porphyrinoid. The color change from porphycene to isocorrole is from blue to green and purple, indicated by the background colors. The background design and color also implies that the reaction proceeded in one‐pot and the three compounds are co‐existing in the reaction system. The structures...

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INFONA - science communication portal

Search results for: Kazunari Yoshizawa

Catalytic Reduction of Dinitrogen into Ammonia and Hydrazine by Using Chromium Complexes Bearing PCP‐Type Pincer Ligands**

Cover Feature: Catalytic Reduction of Dinitrogen into Ammonia and Hydrazine by Using Chromium Complexes Bearing PCP‐Type Pincer Ligands (Chem. Eur. J. 25/2022)

Heterointerface Created on Au‐Cluster‐Loaded Unilamellar Hydroxide Electrocatalysts as a Highly Active Site for the Oxygen Evolution Reaction (Adv. Mater. 16/2022)

Heterointerface Created on Au‐Cluster‐Loaded Unilamellar Hydroxide Electrocatalysts as a Highly Active Site for the Oxygen Evolution Reaction

Quadruple Role of Pd Catalyst in Domino Reaction Involving Aryl to Alkyl 1,5‐Pd Migration to Access 1,9‐Bridged Triptycenes

Cover Feature: Quadruple Role of Pd Catalyst in Domino Reaction Involving Aryl to Alkyl 1,5‐Pd Migration to Access 1,9‐Bridged Triptycenes (Chem. Eur. J. 45/2021)

Ammonia Formation Catalyzed by a Dinitrogen‐Bridged Dirhenium Complex Bearing PNP‐Pincer Ligands under Mild Reaction Conditions**

Ammonia Formation Catalyzed by a Dinitrogen‐Bridged Dirhenium Complex Bearing PNP‐Pincer Ligands under Mild Reaction Conditions**

Synthesis, spectral characterization, density functional theory studies, and biological screening of some transition metal complexes of a novel hydrazide–hydrazone ligand of isonicotinic acid

Cycling between Molybdenum‐Dinitrogen and ‐Nitride Complexes to Support the Reaction Pathway for Catalytic Formation of Ammonia from Dinitrogen

Cycling between Molybdenum‐Dinitrogen and ‐Nitride Complexes to Support the Reaction Pathway for Catalytic Formation of Ammonia from Dinitrogen

Front Cover: Cycling between Molybdenum‐Dinitrogen and ‐Nitride Complexes to Support the Reaction Pathway for Catalytic Formation of Ammonia from Dinitrogen (Chem. Eur. J. 59/2020)

Three‐Step Spin State Transition and Hysteretic Proton Transfer in the Crystal of an Iron(II) Hydrazone Complex

Three‐Step Spin State Transition and Hysteretic Proton Transfer in the Crystal of an Iron(II) Hydrazone Complex

Anthranoxides as Highly Reactive Arynophiles for the Synthesis of Triptycenes

Cover Feature: Anthranoxides as Highly Reactive Arynophiles for the Synthesis of Triptycenes (Chem. Eur. J. 39/2020)

Mechanistic Study on Catalytic Disproportionation of Hydrazine by a Protic Pincer‐Type Iron Complex through Proton‐Coupled Electron Transfer

Nitrogen Fixation Catalyzed by Dinitrogen‐Bridged Dimolybdenum Complexes Bearing PCP‐ and PNP‐Type Pincer Ligands: A Shortcut Pathway Deduced from Free Energy Profiles

Mechanistic Study on Ring‐Contracting Skeletal Rearrangement from Porphycene to Isocorrole by Experimental and Theoretical Methods

Cover Feature: Mechanistic Study on Ring‐Contracting Skeletal Rearrangement from Porphycene to Isocorrole by Experimental and Theoretical Methods (Eur. J. Org. Chem. 12/2020)

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