A low cost, high accuracy method for halogen bonding complexes.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Modeling

Background:

• Halogen bonding (XB) is a crucial non-covalent interaction in chemistry.
• Accurate modeling of XB in large systems is computationally expensive with traditional Density Functional Theory (DFT) methods.
• Existing methods struggle with the computational scaling for systems exceeding 40 atoms.

Purpose of the Study:

• To develop a computationally efficient method for modeling halogen bond geometries and energies.
• To assess the accuracy of the ONIOM scheme M052X/[Def2TZVP+Def2TZVPD.ECP(I)]:AM1 for large systems.
• To provide a faster alternative to DFT for studying complex halogen bonding interactions.

Main Methods:

• Utilized the ONIOM scheme M052X/[Def2TZVP+Def2TZVPD.ECP(I)]:AM1 for geometry optimization.
• Compared ONIOM results with established DFT calculations for accuracy.
• Employed single-point energy calculations at the DFT level on ONIOM-optimized geometries for complexation free energies.

Main Results:

• The ONIOM scheme accurately reproduced halogen bond geometries, comparable to DFT.
• The ONIOM method demonstrated over two orders of magnitude speedup for systems >40 atoms.
• Accurate complexation free energies were obtained using ONIOM geometries and DFT single-point energies.
• The approach was validated across 40 XB donors and various neutral/anionic Lewis bases.

Conclusions:

• The ONIOM scheme provides a highly accurate and significantly faster approach for modeling halogen bonding in large molecular systems.
• This method overcomes the computational limitations of DFT for extensive XB studies.
• Enables more efficient research into complex systems involving halogen bonding.