Carbon dioxide activation by surface excess electrons: an EPR study of the CO2- radical ion adsorbed on the surface of MgO.

The CO2- radical anion has been generated at the surface of MgO by direct electron transfer from surface trapped excess electrons and characterized by electron paramagnetic resonance spectroscopy. Both 13C and 17O hyperfine structures have been resolved for the first time, leading to a detailed mapping of the unpaired electron spin density distribution over the entire radical anion. The magnetic equivalence of the two O nuclei has been ascertained allowing a side-on adsorption structure at low-coordinate Mg2+ ions to be proposed for the surface stabilized radical.