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6. Hydrogenation of CO2, carbonyl and imine substrates catalyzed by [IrH3(PhPNHP)] complex

Author

Munirathinam Nethaji, Balaji R. Jagirdar, and Ayyappan Ramaraj

Subjects
Hydrogen bond, Organic Chemistry, Imine, chemistry.chemical_element, Crystal structure, Biochemistry, Medicinal chemistry, Catalysis, Rhodium, Inorganic Chemistry, chemistry.chemical_compound, chemistry, Materials Chemistry, Iridium, Physical and Theoretical Chemistry, Pincer ligand, Bifunctional
Abstract

A series of iridium and rhodium complexes M(COD)((PNP)-P-Ph-P-H)]Cl {M = Ir (1), Rh (2)}, MH2Cl((PNP)-P-Ph-P-H)] {M = Ir (3), Rh (4)} and IrH3((PNP)-P-Ph-P-H)] (6) supported by pincer ligand HeN(CH2CH2PPh2)(2) {(PNP)-P-Ph-P-H} have been synthesized and characterized. All complexes were isolated in good yields. The iridium trihydride complex IrH3((PNP)-P-Ph-P-H)] (6) was found to be an active catalyst for the hydrogenation of CO2 in 1 M aqueous KOH solution. It also acts as a catalyst for the base-free hydrogenation of carbonyl and imine substrates in MeOH. Under similar hydrogenation conditions, 2-cyclohexen-1-one undergoes solvent assisted tandem Michael addition-reduction mediated by bifunctional Lewis-acid-catalyst IrH3((PNP)-P-Ph-P-H)] in ROH (R = Me, Et) at room temperature. The complexes 1, 3, 4, and 6 were characterized by X-ray crystallography. Extensive hydrogen bonding interactions N-H center dot center dot center dot H-Ir (2.15 angstrom), N-H center dot center dot center dot center dot Cl (2.370 angstrom) were noted in the crystal structures of these complexes. (C) 2018 Elsevier B.V. All rights reserved.

Published
2019
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8. Recent developments on the transformation of CO2 utilising ligand cooperation and related strategies.

Author

Ayyappan, Ramaraj, Abdalghani, Issam, Da Costa, Rosenildo C., and Owen, Gareth R.

Subjects
*COOPERATION, *TRANSITION metals
Abstract

A portfolio of value-added chemicals, fuels and building block compounds can be envisioned from CO2 on an industrial scale. The high kinetic and thermodynamic stabilities of CO2, however, present a significant barrier to its utilisation as a C1 source. In this context, metal–ligand cooperation methodologies have emerged as one of the most dominant strategies for the transformation of the CO2 molecule over the last decade or so. This review focuses on the advancements in CO2 transformation using these cooperative methodologies. Different and well-studied ligand cooperation methodologies, such as dearomatisation–aromatisation type cooperation, bimetallic cooperation (M⋯M′; M′ = main group or transition metal) and other related strategies are also discussed. Furthermore, the cooperative bond activations are subdivided based on the number of atoms connecting the reactive centre in the ligand framework (spacer/linker length) and the transition metal. Several similarities across these seemingly distinct cooperative methodologies are emphasised. Finally, this review brings out the challenges ahead in developing catalytic systems from these CO2 transformations. [ABSTRACT FROM AUTHOR]

Published
2022
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