Why Low Valent Lead(II) Hydride Complex Would be a Better Catalyst for CO2 Activation than Its 14 Group Analogues?

Abstract

A low valent Pb(II) hydride complex with NacNac ligand (NacNac = [ArNC(Me)CHC (Me)NAr]−, with Ar = 2,6–iPr2C6H3) is predicted to be the best catalyst for CO2 activation compared to its Ge(II) and Sn(II) analogues, which have been experimentally reported (Jana, A., et al. J. Am. Chem. Soc. 2009, 131, 1288;Jana, A. et al. Angew. Chem. Int. Ed. 2009, 48, 1106). The CO2 activation mechanism mediated by Ge(II), Sn(II) and Pb(II) catalysts was studied in toluene using density functional theory calculations. The results show that the activation can be carried out through two reaction pathways, giving rise to two different conformers which have been computationally predicted for the first time. In all the cases, the activation process was thermodynamically favored, in addition, the Pb(II) catalyst exhibited the lowest activation energy, compared with Ge(II), Sn(II), and even Si(II). Thus, it was found that, going down in group 14, the reactivity of the NacNac based complexes toward CO2 activation increases consid...