Halogen Bonds under Electric Field with Quantum Accuracy and Relativistic Basis Sets

Area of Science:

• Supramolecular Chemistry
• Computational Chemistry
• Quantum Chemistry

Background:

• Halogen bonds (XBs) are vital in supramolecular chemistry.
• Their response to external perturbations, especially with heavy elements and relativistic effects, is under-investigated.

Purpose of the Study:

• To benchmark quantum chemical methods for studying electric field effects on halogen bonds.
• To assess the impact of relativistic treatments and basis sets on XB properties.

Main Methods:

• Quantum chemical calculations (CCSD, CCSD(T)) on ClI···N(CH3)3 and ClI···NCH complexes.
• Benchmarking relativistic vs. non-relativistic basis sets (jorge-TZP-DKH, def2-TZVP, SDD, LANL2DZ).
• Assessing density functional theory (M06-2X, B3LYP) and Symmetry-Adapted Perturbation Theory (SAPT).

Main Results:

• Explicit relativistic treatments significantly reduce exaggerated electric field responses.
• Relativistic basis set choice impacts results more than functional choice.
• Electrostatics dominate XB stabilization, with induction increasing under positive fields.

Conclusions:

• Halogen bonds are demonstrably more sensitive to electric fields than hydrogen bonds.
• Accurate modeling requires explicit consideration of relativistic effects for heavy elements.