A highly active alkane dehydrogenation catalyst: stabilization of dihydrido rhodium and iridium complexes by a P–C–P pincer ligand

1996 ◽  
pp. 2083-2084 ◽  
Author(s):  
Mukta Gupta ◽  
Chrystel Hagen ◽  
Robert J. Flesher ◽  
William C. Kaska ◽  
Craig M. Jensen
Keyword(s):  
Iridium Complexes ◽  
Pincer Ligand ◽  
Alkane Dehydrogenation ◽  
Highly Active ◽  
Catalyst Stabilization

scholarly journals Post Synthetic Defect Engineering of UiO-66 Metal-Organic Framework with Iridium(III)-HEDTA Complex and Application in Catalysis for Water Oxydation

2019 ◽  
Author(s):  
Ferdinando Costantino ◽  
Alceo Macchioni ◽  
Giordano Gatto ◽  
Roberto Bondi ◽  
Fabio Marmottini
Keyword(s):  
Water Oxidation ◽  
Metal Organic Framework ◽  
Partial Substitution ◽  
Iridium Complexes ◽  
Defect Engineering ◽  
Cerium Ammonium Nitrate ◽  
Highly Active ◽  
Metal Organic ◽  
Heterogenous Catalyst ◽  
Sacrificial Agent

Clean production of renewable fuels is a great challenge of our scientific community. Iridium complexes have demonstrated a superior catalytic activity in the water oxidation (WO) reaction, which is a crucial step in water splitting process. Herein we have used a defective zirconium MOF with UiO-66 structure as support of a highly active Ir complex based on EDTA with formula [Ir(HEDTA)Cl]Na. The defects are induced by the partial substitution of tereftalic acid with smaller formiate groups. Anchoring of the complex occurs through a post-synthetic exchange of formiate anions, coordinated at the zirconium clusters of the MOF, with the free carboxylate group of the [Ir(HEDTA)Cl]-complex. The modified material was tested as heterogenous catalyst for the WO reaction by using Cerium Ammonium Nitrate as sacrificial agent. Although TOF and TON values are comparable to those of other iridium heterogenized catalysts, the MOF exhibits iridium leaching not limited at the first catalytic run, as usually observed, suggesting a lack of stability of the hybrid system under strong oxidative conditions.

scholarly journals Post Synthetic Defect Engineering of UiO-66 Metal–Organic Framework with An Iridium(III)-HEDTA Complex and Application in Water Oxidation Catalysis

Inorganics ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 123 ◽  
Author(s):  
Giordano Gatto ◽  
Alceo Macchioni ◽  
Roberto Bondi ◽  
Fabio Marmottini ◽  
Ferdinando Costantino
Keyword(s):  
Water Oxidation ◽  
Metal Organic Framework ◽  
Oxidation Catalysis ◽  
Partial Substitution ◽  
Iridium Complexes ◽  
Cerium Ammonium Nitrate ◽  
Highly Active ◽  
Water Oxidation Catalysis ◽  
Metal Organic ◽  
Organic Framework

Clean production of renewable fuels is a great challenge of our scientific community. Iridium complexes have demonstrated a superior catalytic activity in the water oxidation (WO) reaction, which is a crucial step in water splitting process. Herein, we have used a defective zirconium metal–organic framework (MOF) with UiO-66 structure as support of a highly active Ir complex based on EDTA with the formula [Ir(HEDTA)Cl]Na. The defects are induced by the partial substitution of terephthalic acid with smaller formate groups. Anchoring of the complex occurs through a post-synthetic exchange of formate anions, coordinated at the zirconium clusters of the MOF, with the free carboxylate group of the [Ir(HEDTA)Cl]− complex. The modified material was tested as a heterogeneous catalyst for the WO reaction by using cerium ammonium nitrate (CAN) as the sacrificial agent. Although turnover frequency (TOF) and turnover number (TON) values are comparable to those of other iridium heterogenized catalysts, the MOF exhibits iridium leaching not limited at the first catalytic run, as usually observed, suggesting a lack of stability of the hybrid system under strong oxidative conditions.

N-Bridged Pincer Iridium Complexes for Highly Efficient Alkane Dehydrogenation and the Relevant Linker Effects

ACS Catalysis ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 6475-6487 ◽  
Author(s):  
Xin Zhang ◽  
Song-Bai Wu ◽  
Xuebing Leng ◽  
Lung Wa Chung ◽  
Guixia Liu ◽  
...  
Keyword(s):  
Iridium Complexes ◽  
Alkane Dehydrogenation ◽  
Highly Efficient

scholarly journals Experimental and computational study of alkane dehydrogenation catalyzed by a carbazolide-based rhodium PNP pincer complex

2016 ◽  
Vol 7 (4) ◽  
pp. 2579-2586 ◽  
Author(s):  
David Bézier ◽  
Changjian Guan ◽  
Karsten Krogh-Jespersen ◽  
Alan S. Goldman ◽  
Maurice Brookhart
Keyword(s):  
Computational Study ◽  
Rhodium Complex ◽  
Pincer Ligand ◽  
Alkane Dehydrogenation ◽  
Pincer Complex

A rhodium complex based on the bis-phosphine carbazolide pincer ligand was investigated in the context of alkane dehydrogenation and in comparison with its iridium analogue.

scholarly journals Crystal structure of an iridium(III) complex of the [C(dppm)2] PCP pincer ligand system and its conjugate CH acid form

2018 ◽  
Vol 74 (5) ◽  
pp. 620-624 ◽  
Author(s):  
Christian Reitsamer ◽  
Inge Schlapp-Hackl ◽  
Gabriel Partl ◽  
Walter Schuh ◽  
Holger Kopacka ◽  
...  
Keyword(s):  
Carbon Atom ◽  
Iridium Complexes ◽  
Pincer Ligand ◽  
Single Crystal Diffraction ◽  
Dalton Trans ◽  
Ligand System ◽  
Distorted Octahedral ◽  
Major Interest ◽  
Carbonyl Bond ◽  
Pcp Pincer

After the successful creation of the newly designed PCP carbodiphosphorane (CDP) ligand [Reitsamer et al. (2012). Dalton Trans. 41, 3503–3514; Stallinger et al. (2007). Chem. Commun. pp. 510–512], the treatment of this PCP pincer system with the transition metal iridium and further the analysis of the structures by single-crystal diffraction and by NMR spectroscopy were of major interest. Two different iridium complexes, namely (bis{[(diphenylphosphanyl)methyl]diphenylphosphanylidene}methane-κ3 P,C,P′)carbonylchloridohydridoiridium(III) chloride dichloromethane trisolvate, [IrIII(CO){C(dppm)2-κ3 P,C,P′}ClH]Cl·3CH2Cl2 (1) and the closely related (bis{[(diphenylphosphanyl)methyl]diphenylphosphanylidene}methanide(1+)-κ3 P,C,P′)carbonylchloridohydridoiridium(III) dichloride–hydrochloric acid–water (1/2/5.5), [IrIII(CO){CH(dppm)2-κ3 P,C,P′)ClH]Cl}2 (2), have been designed and both complexes show a slightly distorted octahedral coordinated IrIII centre. The PCP pincer ligand system is arranged in a meridional manner, the CO ligand is located trans to the central PCP carbon and a hydride and chloride are located perpendicular above and below the P2C2 plane. With an Ir—CCDP distance of 2.157 (5) Å, an Ir—CO distance of 1.891 (6) Å and a quite short C—O distance of 1.117 (7) Å, complex 1 presents a strong carbonyl bond. Complex 2, the corresponding CH acid of 1, shows an additionally attached proton at the carbodiphosphorane carbon atom located antiperiplanar to the hydride of the metal centre. In comparison with complex 1, the Ir—CCDP distance of 2.207 (3) Å is lengthened and the Ir—C—O values indicate a weaker trans influence of the central carbodiphosphorane carbon atom.

scholarly journals Cationic NHC‐Phosphine Iridium Complexes: Highly Active Catalysts for Base‐Free Hydrogenation of Ketones

2020 ◽  
Vol 26 (58) ◽  
pp. 13311-13316
Author(s):  
Xu Quan ◽  
Sutthichat Kerdphon ◽  
Bram B. C. Peters ◽  
Janjira Rujirawanich ◽  
Suppachai Krajangsri ◽  
...  
Keyword(s):  
Iridium Complexes ◽  
Highly Active

Kinetics and selectivity of methane oxidation on an IrO2(110) film

2021 ◽  
Author(s):  
Christopher J Lee ◽  
Saumye Vashishtha ◽  
Mohammed Shariff ◽  
Fangrong Zou ◽  
Junjie Shi ◽  
...  
Keyword(s):  
Low Temperature ◽  
Methane Oxidation ◽  
High Stability ◽  
Product Formation ◽  
Product Selectivity ◽  
Alkane Dehydrogenation ◽  
Highly Active ◽  
Temperature Programmed ◽  
Temperature Programmed Reaction Spectroscopy ◽  
Temperature Programmed Reaction

Abstract Undercoordinated, bridging O-atoms (Obr) are highly active as H-acceptors in alkane dehydrogenation on IrO2(110) surfaces but transform to HObr groups that are inactive toward hydrocarbons. The low C-H activity and high stability of the HObr groups cause the kinetics and product selectivity during CH4 oxidation on IrO2(110) to depend sensitively on the availability of Obr atoms prior to the onset of product desorption. From temperature programmed reaction spectroscopy (TPRS) and kinetic simulations, we identified two Obr-coverage regimes that distinguish the kinetics and product formation during CH4 oxidation on IrO2(110). Under excess Obr conditions, when the initial Obr coverage is greater than that needed to oxidize all the CH4 to CO2 and HObr groups, complete CH4 oxidation is dominant and produces CO2 in a single TPRS peak between 450 and 500 K. However, under Obr-limited conditions, nearly all the initial Obr atoms are deactivated by conversion to HObr or abstracted after only a fraction of the initially adsorbed CH4 oxidizes to CO2 and CO below 500 K. Thereafter, some of the excess CHx groups abstract H and desorb as CH4 above ~500 K while the remainder oxidize to CO2 and CO at a rate that is controlled by the rate at which Obr atoms are regenerated from HObr during the formation of CH4 and H2O products. We also show that chemisorbed O-atoms (“on-top O”) on IrO2(110) enhance CO2 production below 500 K by efficiently abstracting H from Obr atoms and thereby increasing the coverage of Obr atoms available to completely oxidize CHx groups at low temperature. Our results provide new insights for understanding factors which govern the kinetics and selectivity during CH4 oxidation on IrO2(110) surfaces.

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