CO2 binding in the (quinoline-CO2)(-) anionic complex.

ABSTRACT

We have studied the (quinoline-CO2)(-) anionic complex by a combination of mass spectrometry, anion photoelectron spectroscopy, and density functional theory calculations. The (quinoline-CO2)(-) anionic complex has much in common with previously studied (N-heterocycle-CO2)(-) anionic complexes both in terms of geometric structure and covalent bonding character. Unlike the previously studied N-heterocycles, however, quinoline has a positive electron affinity, and this provided a pathway for determining the binding energy of CO2 in the (quinoline-CO2)(-) anionic complex. From the theoretical calculations, we found CO2 to be bound within the (quinoline-CO2)(-) anionic complex by 0.6 eV. We also showed that the excess electron is delocalized over the entire molecular framework. It is likely that the CO2 binding energies and excess electron delocalization profiles of the previously studied (N-heterocycle-CO2)(-) anionic complexes are quite similar to that of the (quinoline-CO2)(-) anionic complex. This class of complexes may have a role to play in CO2 activation and/or sequestration.