Hyperconjugative effects in π-hydrogen bonding: Theory and experiment.
Boris GalabovValia NikolovaDiana CheshmedzhievaBoriana HadjievaHenry F SchaeferPublished in: Journal of computational chemistry (2017)
Density functional theory computations with the B3LYP/6-311++G(2df,2p) method and IR spectroscopy are employed in investigating the properties of twenty π-hydrogen bonded complexes between substituted phenols and hexamethylbenzene. All complexes possess T-shaped structures. The methyl hyperconjugative effects on interactions energies and OH stretching frequencies are estimated via comparisons with previously reported theoretical and experimental results for analogous phenol complexes with benzene. The theoretical computations provide excellent quantitative predictions of the OH stretching frequency shifts (ΔνOH ) resulting from the hydrogen bonding. The ΔνOH shifts in the hexamethylbenzene complexes are approximately twice as large as the corresponding shifts for the benzene complexes. Hirshfeld charges, electrostatic potential at nuclei values, and molecular electrostatic potential maps are employed in gaining insights into the mechanisms of methyl hyperconjugative effects on complex formation. © 2017 Wiley Periodicals, Inc.