Interaction of second-row dicarbides with molecular oxygen: A theoretical study

In this work, we report our calculations, based on density functional theory (DFT) to investigate the molecular adsorption of O2 on the second-row dicarbides, C2X, with X = Na, Mg, Al, Si, S, P, and Cl. It is found that all the second-row dicarbides, except C2Si, almost retain their structures while reacting with O2 molecule, whereas the ground-state structure of C2Si which is reported to be cyclic, however, becomes linear in presence of O2. Similarly, the ground-state structure of C2S cluster which is reported to be triplet becomes singlet while interacting with O2 molecule, with the triplet state 1.08 eV higher in energy. The O–O stretching frequencies in the complex C2XO2 are red-shifted as compared to that in O2 molecule, whereas the C–C stretching frequencies are observed to increase. Negative adsorption and Gibb’s free energies indicate that the adsorptions are thermodynamically favorable. Moreover, the existence of disynpatic basins V (C, O) and their corresponding higher covariance values based on ELF topological analysis infers that the electrons are delocalized in these areas giving rise to shared-electron interactions.