Mechanistic insights from theory on the reduction of CO2, N2O, and SO2 molecules using tripodal diimine-enolate substituted magnesium(i) dimers

Abstract

The mechanistic investigation of the reductive coupling vs. reductive disproportionation of CO₂ using magnesium(I) dimers bearing tripodal ligands, [{Mg[κ³-N,N′,O-(ArNCMe)₂(OCCPh₂)CH]}₂] (Ar = C₆H₃Et₂-2,6) has been carried out using DFT computational methods. We also elucidated the reduction of N₂O to form a μ-oxo magnesium complex which upon addition of CO₂ affords the experimentally observed carbonate complex. Finally, the interesting reactivity towards SO₂ is considered and some insights into the mechanistic aspects of such activation/homo-coupling reaction are given for both “Nacnac” substituted magnesium(I) dimers ([{(^DipNacnac)Mg}₂] (^DipNacnac = [(DipNCMe)₂CH]⁻, Dip = C₆H₃Prⁱ₂-2,6)) and those bearing tripodal ligands. The analogy between the activation chemistry of low-valent f-block metal complexes with that of magnesium systems is highlighted.