The mechanistic investigation of the reductive coupling vs. reductive disproportionation of CO2 using magnesium(i) dimers bearing tripodal ligands, [{Mg[κ(3)-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 ([{((Dip)Nacnac)Mg}2] ((Dip)Nacnac = [(DipNCMe)2CH](-), Dip = C6H3Pr(i)2-2,6)) 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.