This study used mpw1pw91 quantum chemical calculations in gas and solution phases to clarify the interaction between C20and Cr(CO)5fragment. It also sought to clarify the effects of solvent polarity on dipole moment, structural parameters, and frontier orbital energies of the complex. Energy decomposition analysis (EDA) was applied to analyze the bonding interaction between the C20and Cr(CO)5fragment. Percentage composition in terms of the defined groups of frontier orbitals for the complex was evaluated to characterize the metal–ligand bonds. The Cr–C bonds within the complex were examined using quantum theory of atoms in molecules (QTAIM) analysis. In order to determine the back-bonding effects in these bonds, QTAIM analysis was applied to calculate of the quadrupole polarization of the carbon atom.