Revisiting the Hunter-Sanders Model for π-π Interactions.

Area of Science:

• Computational chemistry
• Physical chemistry
• Chemical physics

Background:

• The Hunter-Sanders model is a foundational theory for understanding aromatic system interactions.
• Recent work challenged its predictions, attributing parallel displaced geometries to steric repulsion rather than Coulombic forces.
• This study re-evaluates the Hunter-Sanders potential's accuracy against recent findings.

Purpose of the Study:

• To critically assess the validity of the Hunter-Sanders potential in predicting aromatic dimer geometries.
• To re-examine the claims made by Carter-Fenk and Herbert regarding the Hunter-Sanders potential's predictive failures.
• To clarify the strengths and weaknesses of the Hunter-Sanders potential for various aromatic systems.

Main Methods:

• Re-implementation and analysis of the Hunter-Sanders potential.
• Comparison of predicted geometries with experimental and computational data for parallel and T-shaped aromatic dimers.
• Evaluation of the potential's performance with substituted benzene dimers and heterocyclic systems.

Main Results:

• The Hunter-Sanders potential, when correctly implemented, provides qualitatively accurate predictions for T-shaped benzene dimers.
• It accurately captures the enhancing effect of substituents on benzene sandwich dimer stacking.
• The potential, however, inaccurately predicts displacement directions for some parallel displaced geometries with substituents over the ring.

Conclusions:

• The Hunter-Sanders potential retains qualitative accuracy for certain aromatic interactions, particularly T-shaped dimers.
• Recent criticisms regarding its predictive failures are based on flawed data or implementation.
• While not universally perfect, the Hunter-Sanders potential remains a valuable tool for understanding specific aromatic interactions.