Polymer-bound metal complexes as catalysts: Synthesis, characterization, reactivity and catalytic activity in E–H bond activation

2011 ◽  
Vol 696 (1) ◽  
pp. 244-254 ◽  
Author(s):  
Mannar R. Maurya ◽  
João Costa Pessoa
Keyword(s):  
Catalytic Activity ◽  
Metal Complexes ◽  
Bond Activation

scholarly journals CO Oxidation Efficiency and Hysteresis Behavior over Mesoporous Pd/SiO2 Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 131 ◽  
Author(s):  
Rola Mohammad Al Soubaihi ◽  
Khaled Mohammad Saoud ◽  
Myo Tay Zar Myint ◽  
Mats A. Göthelid ◽  
Joydeep Dutta
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Active Sites ◽  
Bond Activation ◽  
Dissociative Adsorption ◽  
High Catalytic Activity ◽  
Good Catalytic Activity ◽  
Pretreatment Conditions ◽  
Oxidation Efficiency

Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO2 aerogel catalysts exhibit good catalytic activity toward this reaction owing to their CO bond activation capability and thermal stability. Pd/SiO2 catalysts were investigated using carbon monoxide (CO) oxidation as a model reaction. The catalyst becomes active, and the conversion increases after the temperature reaches the ignition temperature (Tig). A normal hysteresis in carbon monoxide (CO) oxidation has been observed, where the catalysts continue to exhibit high catalytic activity (CO conversion remains at 100%) during the extinction even at temperatures lower than Tig. The catalyst was characterized using BET, TEM, XPS, TGA-DSC, and FTIR. In this work, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis is presented. The CO oxidation on the Pd/SiO2 catalyst has been attributed to the dissociative adsorption of molecular oxygen and the activation of the C-O bond, followed by diffusion of adsorbates at Tig to form CO2. Whereas, the hysteresis has been explained by the enhanced stability of the active site caused by thermal effects, pretreatment conditions, Pd-SiO2 support interaction, and PdO formation and decomposition.

Recent Advances in Transition Metal Catalyzed C-H Functionalization Reactions Involving Aza/Oxabicyclic Alkenes

Synthesis ◽  
2021 ◽  
Author(s):  
Masilamani Jeganmohan ◽  
Pinki Sihag
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Ring Opening ◽  
Bond Activation ◽  
Considerable Progress ◽  
Double Bonds ◽  
Facial Selectivity ◽  
Ring Opening Reactions ◽  
Metal Catalyzed

Bicyclic alkenes, including Oxa- and azabicyclic alkenes can be readily activated by using transition-metal complexes with facial selectivity, because of the intrinsic angle strain on carbon-carbon double bonds of these unsymmetrical bicyclic systems. During last decades considerable progress has been done in the area of ring-opening of bicyclic strained ring by employing the concept of C-H activation. This Review comprehensively compiles the various C-H bond activation assisted reactions of oxa- and azabicyclic alkenes, viz., ring-opening reactions, hydroarylation as well as annulation reactions.

scholarly journals The Exchange of Cyclometalated Ligands

Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 210
Author(s):  
Alexander D. Ryabov
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Bond Activation ◽  
Bond Cleavage ◽  
Cyclopalladated Complexes ◽  
Derivatives Of ◽  
Cyclometalated Ligand ◽  
Incoming Ligand

Reactions of cyclometalated compounds are numerous. This account is focused on one of such reactions, the exchange of cyclometalated ligands, a reaction between a cyclometalated compound and an incoming ligand that replaces a previously cyclometalated ligand to form a new metalacycle: + H-C*~Z ⇄ + H-C~Y. Originally discovered for PdII complexes with Y/Z = N, P, S, the exchange appeared to be a mechanistically challenging, simple, and convenient routine for the synthesis of cyclopalladated complexes. Over four decades it was expanded to cyclometalated derivatives of platinum, ruthenium, manganese, rhodium, and iridium. The exchange, which is also questionably referred to as transcyclometalation, offers attractive synthetic possibilities and assists in disclosing key mechanistic pathways associated with the C–H bond activation by transition metal complexes and C–M bond cleavage. Both synthetic and mechanistic aspects of the exchange are reviewed and discussed.

Polymer-Bound 1-Aryl-3-alkyltriazenes as Modular Ligands for Catalysis. Part 2: Screening Immobilized Metal Complexes for Catalytic Activity

2002 ◽  
Vol 12 (14) ◽  
pp. 1849-1851 ◽  
Author(s):  
Stefan Bräse ◽  
Stefan Dahmen ◽  
Frank Lauterwasser ◽  
Nicholas E. Leadbeater ◽  
Emma L. Sharp
Keyword(s):  
Catalytic Activity ◽  
Metal Complexes

scholarly journals Metal Complexes of Schiff Bases of 3-Hydroxyquinoxaline-2-carboxaldehyde Encapsulated in Zeolite Y Cages: Potential Catalyst for Removing Phenol from Effluent Media

2021 ◽  
Vol 33 (11) ◽  
pp. 2746-2754
Author(s):  
N.R. Suja ◽  
T.K. Bindu Sharmila ◽  
S.R. Amrutha
Keyword(s):  
Catalytic Activity ◽  
Transition Metal ◽  
Metal Complexes ◽  
Schiff Bases ◽  
Transition Metal Complexes ◽  
Zeolite Y ◽  
Point Of View ◽  
Organic Transformations ◽  
Efficient Catalyst ◽  
Industrial Pollutants

Transition metal complexes are known to be efficient catalyst for many organic transformations. Encapsulation of metal complexes in zeolite cage brings many significant modifications in the structure of the metal complexes, which are very interesting from the catalytic point of view. This study aims in a comparative evaluation of the influence of structure of neat and encapsulated complexes in their catalytic activity. Phenol is one of the major industrial pollutants. Heterogenizing transition metal Schiff bases by encapsulation inside the zeolite would help to minimize the reuse problem of transition metal complexes. This article deals with the synthesis, characterization and catalytic activity studies of Co(II), Ni(II) and Cu(II) complexes of 3-hydroxyquinoxaline-2-carboxaldehyde with ethylenediamine (L1) and an o-phenylene diamine (L2).

scholarly journals THE METAL COMPLEXES OF NOVEL SCHIFF BASE CONTAINING ISATIN: CHARACTERIZATION, ANTIMICROBIAL, ANTIOXIDANT AND CATALYTIC ACTIVITY STUDY

2019 ◽  
pp. 206-210
Author(s):  
VAIRALAKSHMI M ◽  
PRINCESS R ◽  
JOHNSON RAJA S
Keyword(s):  
Catalytic Activity ◽  
Metal Complexes ◽  
1H Nmr ◽  
Metal Ion ◽  
Analytical Data ◽  
Free Ligand ◽  
Molar Conductance ◽  
Diffusion Method ◽  
Spectral Studies ◽  
Standard Drug

Objectives: The aim of our work was to synthesize novel mixed ligand-metal complexes and evaluation of antimicrobial, antioxidant assay, and analysis of catalytic oxidation of cyclohexane. Methods: The complexes were characterized by means of various physicochemical techniques such as elemental analysis, molar conductance, magnetic susceptibility, infrared (IR), electronic absorption, 1H NMR (proton magnetic resonance), and mass spectral studies. The antimicrobial screening study was done by disc diffusion method. The catalytic activity of the complexes was observed in the oxidation of cyclohexane using eco-friendly hydrogen peroxide as oxidant. Results: On comparing the 1H NMR and IR spectral data of free ligand and its complexes, it was found to be azomethine (CH=N) proton which is formed in the free ligand. During complexation, the azomethine proton is coordinated to the metal ion and the phenolic oxygen is coordinated to the metal ion by deprotonation. The analytical data and mass spectra of the ligand and the complexes confirm the stoichiometry of metal complexes as being of the (MLY)Cl type and the metal to ligand ratio is 1:1. The antimicrobial, antioxidant, and catalytic potential were evaluated and the result shows the better activity of the complexes than the ligand. Conclusion: It was found to be copper(II) and zinc(II) complexes which are effective against all the bacteria when compared to standard drug streptomycin. Copper(II) complex was found to be effective antibacterial agent against Aspergillus niger and Aspergillus flavus in comparison to the standard drug Nystatin. The zinc complex exhibited good catalytic activity.

Catalytic Activity of Histidine-Metal Complexes in Oxidation Reactions

2013 ◽  
Vol 43 (3) ◽  
pp. 243-249 ◽  
Author(s):  
Krassimir Vassilev ◽  
Marina Dimitrova ◽  
Sevdalina Turmanova ◽  
Rumyana Milina
Keyword(s):  
Catalytic Activity ◽  
Metal Complexes ◽  
Oxidation Reactions
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