Correlation between Noncovalent Bond Strength and Spectroscopic Perturbations within the Lewis Base

Me₂CO was allowed to interact with 20 different Lewis acids so as to engage in various sorts of noncovalent interactions, encompassing hydrogen, halogen, chalcogen, pnictogen, and tetrel bonds. Density functional theory computations evaluated the interaction energy of each dyad, which was compared with spectroscopic, geometric, AIM, and energy decomposition elements so as to elucidate any correlations. The red shift of the C═O stretching frequency, and the changes in the nuclear magnetic resonance shielding of the O and C atoms of acetone, are closely correlated with the interaction energy so can be used to estimate the latter from experimental measurements. The standard AIM measures at the bond critical point, ρ, ∇²ρ, and <i>V</i> also correlate with the energy, albeit not as well as the spectroscopic parameters. The σ-hole depth on the Lewis acid is not well correlated with the energetics, due in part to the fact that electrostatics in general are not an accurate metric of bond strength.