Computational studies on the hydride transfer barrier for the catalytic hydrogenation of CO₂ by different Ni(II)...

Hydride transfer is the most crucial step for the catalytic hydrogenation of CO₂ in homogeneous condition. Here, we perform state-of-the-art calculations to show the effect of geometry and spin states of Ni-hydride complexes containing different types of multidentate phosphine ligands on their hydride transfer barrier. For doing this, we first choose Ni-bis(diphosphine) complexes of the type NiP₄, which have been synthesized recently and then by extrapolating the idea we propose a new type of NiP₂N₂ complex showing much lower hydride transfer barrier. We also compute the hydricities of the Ni-hydride complexes in aqueous medium and try to correlate these thermodynamic quantities with the kinetic barrier of hydride transfer. Graphical Abstract NiP₂N₂ complex can efficiently hydrogenage CO₂ with a quite low hydride transfer barrier.