Dataset Information

Catalytic reactivity of an iridium complex with a proton responsive N-donor ligand in CO₂ hydrogenation to formate.

ABSTRACT: Catalytic hydrogenation of CO₂ into formic acid/formate is an attractive conversion in the utilization of CO₂. Although various catalysts with high catalytic efficiency are reported, a very few studies have been carried out to correlate/understand the efficacy and stability of the hydrogenation catalysts, which could be helpful to direct the future design strategy of corresponding catalysts. Herein, a half-sandwich iridium complex containing bibenzimidazole as a proton responsive N-donor ligand, [Cp*Ir(BiBzImH₂)Cl]Cl, has been synthesized and fully characterized. The generation of an N^- anion by the deprotonation of a bibenzimidazole group resulted in a significant enhancement of activity. The Ir complex showed about 20 times higher catalytic efficiency in the hydrogenation of CO₂ into formate than that of its bipyridine counterpart [Cp*Ir(Bpy)Cl]Cl. The time dependent catalytic activity studies revealed that the initial excellent activity of [Cp*Ir(BiBzImH₂)Cl]Cl was reduced when catalytic cycle proceeds; which was found to be the structural instability of the catalyst caused by steric hindrance between the bibenzimidazole and Cp* ligands.

SUBMITTER: Gunasekar GH

PROVIDER: S-EPMC9077040 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Catalytic reactivity of an iridium complex with a proton responsive N-donor ligand in CO2 hydrogenation to formate.

Gunasekar Gunniya Hariyanandam GH Yoon Yeahsel Y Baek Il-Hyun IH Yoon Sungho S

RSC advances 20180103 3

Catalytic hydrogenation of CO2 into formic acid/formate is an attractive conversion in the utilization of CO2. Although various catalysts with high catalytic efficiency are reported, a very few studies have been carried out to correlate/understand the efficacy and stability of the hydrogenation catalysts, which could be helpful to direct the future design strategy of corresponding catalysts. Herein, a half-sandwich iridium complex containing bibenzimidazole as a proton resp ...[more]

PMID: 35540928

Similar Datasets

Project description:A rise in atmospheric CO2 levels, following years of burning fossil fuels, has brought about increase in global temperatures and climate change due to the greenhouse effect. As such, recent efforts in addressing this problem have been directed to the use of CO2 as a non-expensive and non-toxic single carbon, C1, source for making chemical products. Herein, we report on the use of tetrazolyl complexes as catalyst precursors for hydrogenation of CO2. Specifically, tetrazolyl compounds bearing P-S bonds have been synthesized with the view of using these as P∧N bidentate tetrazolyl ligands (1-3) that can coordinate to iridium(III), thereby forming heteroatomic five-member complexes. Interestingly, reacting the P,N'-bidentate tetrazolyl ligands with [Ir(C5 Me 5)Cl 2]2 led to serendipitous isolation of chiral-at-metal iridium(III) half-sandwich complexes (7-9) instead. Complexes 7-9 were obtained via prior formation of non-chiral iridium(III) half-sandwich complexes (4-6). The complexes undergo prior P-S bond heterolysis of the precursor ligands, which then ultimately results in new half-sandwich iridium(III) complexes featuring monodentate phosphine co-ligands with proton-responsive P-OH groups. Conditions necessary to significantly affect the rate of P-S bond heterolysis in the precursor ligand and the subsequent coordination to iridium have been reported. The complexes served as catalyst precursors and exhibited activity in CO2 and bicarbonate hydrogenation in excellent catalytic activity, at low catalyst loadings (1 μmol or 0.07 mol% with respect to base), producing concentrated formate solutions (ca 180 mM) exclusively. Catalyst precursors with proton-responsive P-OH groups were found to influence catalytic activity when present as racemates, while ease of dissociation of the ligand from the iridium center was observed to influence activity in spite of the presence of electron-donating ligands. A test for homogeneity indicated that hydrogenation of CO2 proceeded by homogeneous means. Subsequently, the mechanism of the reaction by the iridium(III) catalyst precursors was studied using 1H NMR techniques. This revealed that a chiral-at-metal iridium hydride species generated in situ served as the active catalyst.

Dataset Information

Catalytic reactivity of an iridium complex with a proton responsive N-donor ligand in CO₂ hydrogenation to formate.

Publications

Catalytic reactivity of an iridium complex with a proton responsive N-donor ligand in CO<sub>2</sub> hydrogenation to formate.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets