A computational study on ligand assisted vs. ligand participation mechanisms for CO2 hydrogenation: importance of bifunctional ligand based catalysts. Issue 7 (31st January 2019)

• Record Type: Journal Article
• Authors: Mandal, Shyama Charan; Rawat, Kuber Singh; Pathak, Biswarup
• Is Part Of: Physical chemistry chemical physics. Volume 21:Issue 7(2019)
• Page Start: 3932
• Page End: 3941
• Publication Date: 2019-01-31
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c8cp06714g
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Bifunctional aminomethyl based Mn(i ) catalysts favour a revised Noyori type mechanism for the CO2 hydrogenation reaction. Abstract : CO2 hydrogenation products are not only useful chemical sources but also promising hydrogen storage materials. A DFT study has been carried out on the CO2 hydrogenation reaction catalyzed by a series of bifunctional aminomethyl based Mn(i ) complexes. We find that the N–H functionality in the aminomethyl ligand shows a metal–ligand cooperation (MLC) mechanism for the CO2 hydrogenation reaction. Here, the N–H functionality assists the MLC mechanism by stabilizing the formate anion via N–H⋯O hydrogen bonding interactions. This is opposite to the MLC mechanism proposed by Noyori for ketone hydrogenation, where the N–H functionality actively participates in the reaction mechanism via cleavage/formation of N–H/M–H bonds. Furthermore, the stabilized formate anion initiates heterolytic H2 cleavage, which requires a very low barrier compared to external base/ligand participation heterolytic H2 cleavage. Therefore, the bifunctional aminomethyl based Mn(i ) complexes are promising for the CO2 hydrogenation reaction and our study may be very helpful for experimentalists for the development of efficient bifunctional ligand-based catalysts for the CO2 hydrogenation reaction.