Computational unraveling of the effect of the positioning groups of Ir(III) complexes on catalytic activity

Abstract

In this paper, we present the first comprehensive study on the effects of pincer ligands. By employing density functional theory (DFT), our investigation encompasses the impact of these ligands on various aspects, including the structural stability of the complexes, dearomatization-rearomatization phenomena, hydrogen molecule dissociation, as well as the CO2 hydrogenation reaction to formate. Taking the CO2 hydrogenation reaction as an illustrative example, we discovered that NNN-type ligands play a crucial role in formate formation. Furthermore, we observed that the –CH2 group on the ligands side arm exhibits superior performance compared to the –NH group, displaying a lower energy barrier when coordinated with the NNN-type ligand. Moreover, complexes featuring a methoxy group at the Z position also exhibit a reduced potential barrier.