Formation of sandwich and multidecker complexes between O2 and alkali/alkaline earth metals: a DFT study

Abstract

The feasibility of the formation of sandwich and multidecker complexes between O₂ molecules and alkali/alkaline earth metals has been analyzed in the light of density functional theory (DFT). The high value of the stabilization energy (SE) confirmed strong interactions in such sandwich and multidecker complexes. The total SE of the complexes increases with increase in the size of the complexes, and the average SE exhibits an opposite trend to that of the total SE. The solvent phase results indicate even stronger complexation upon the incorporation of a dielectric solvent. NBO analysis indicated charge transfer upon complexation from the metal to the antibonding π-orbital of O₂. The interaction can be assumed to be primarily covalent in nature, and the process of complexation is thermodynamically favourable. TD-DFT calculations showed a red shift in the absorption maxima upon complexation, which indicates the ability to absorb more in the visible region.