Molecular dynamics (MD) simulations validated against two-dimensional infrared (2D-IR) measurements of CO in an imidazolium-based ionic liquid have revealed new insights into the mechanism of CO solvation. The first solvation shell around CO has a distinctly quadrupolar structure, with strong negative charge density around the CO carbon atom and positive charge density near the CO oxygen atoms. When CO is modeled without atomic charges (thus removing its strong quadrupole moment), its solvation shell weakens and changes significantly into a structure that is similar to that of N in the same liquid. The solvation shell of CO evolves more quickly when its quadrupole is removed, and we find evidence that solvent cage dynamics is measured by 2D-IR spectroscopy. We also find that the solvent cage evolution of N is similar to that of CO with no atomic charges, implying that the weaker quadrupole of N is responsible for its higher diffusion and lower absorption in ionic liquids.