Hydrogenation of Carbon Dioxide with Organic Base by PC^IIP-Ir Catalysts

Abstract

Novel PC II P-Ir I monochloride complexes (1-Cl and 2-Cl) bearing a phosphine-carbene-phosphine pincer type ligand were synthesized. Reactions of 1-Cl with hexachloroethane, hydrogen chloride, and lithium triethylborohydride under a dihydrogen atmosphere afforded PC II P-Ir III trichloride (1-Cl 3 ), hydride dichloride (1-HCl 2 ), and trihydride (1-H 3 ) complexes, respectively. The strong electron-donating ability of carbene in PC II P-Ir complexes was confirmed by X-ray crystallography and DFT calculations. Moreover, in complex 1-Cl, strong π backdonation from the iridium center to the carbene carbon was observed. Hydrogenation of CO 2 with triethanolamine catalyzed by PC II P-Ir complexes was investigated. The novel PC II P-Ir complex 1-Cl exhibited a longer lifetime in comparison to the PNP-Ir III complex 3-H 3 : the turnover number of 1-Cl is significantly higher than that of 3-H 3 (in 46 h, 1-Cl 230000 and 3-H 3 54000).

Transition Metal Complexes Supported by N‐Heterocyclic Carbene‐Based Pincer Platforms: Synthesis, Reactivity and Applications

“…The metalation of 125 a was studied by the same group, and a series of pincer complexes (131-137) of Ni, Rh, Ir and Ru were obtained (scheme 42). [59,60,61] For most cases, a strong base KN(SiMe 3 ) 2 was employed to prepare the free carbene, which underwent subsequent metalation. In contrast, pincer hydrido complexes 133 and were synthesized via an oxidative addition approach.…”

Trans Influence of Boryl Ligands in CO2 Hydrogenation on Ruthenium Complexes: Theoretical Prediction of Highly Active Catalysts for CO2 Reduction

“…The development of high-efficiency catalysts for CO 2 hydrogenation to formic acid or other carbohydrates is still attracting significant attention, as it can address the increasingly severe environmental problems and energy crisis [1][2][3][4][5][6][7]. One of the feasible methods is the homogeneous hydrogenation of CO 2 using noble metal catalysts based on Ir, Ru, and Rh [8][9][10][11][12][13][14]. In 2009, Nozaki and co-workers reported an impressive iridium catalyst (Ir(PNP)H 3 , PNP = 2,6-(diisopropylphosphinomethyl)-pyridine) for CO 2 hydrogenation to formate [8].…”

Anti-Electrostatic Main Group Metal–Metal Bonds That Activate CO2

“…1,2 A majority of reported catalytic systems so far are based on precious transition metals such as rhodium, 3,4 ruthenium, 5−7 and iridium. 8,9 However, the availability of these metals is limited, and their uses are neither economically sustainable nor environmentally friendly. Consequently, there is growing interest in the development of catalytic systems using earthabundant and non-noble (base) metals.…”