Tetrel Bonding in Anion Recognition: A First Principles Investigation

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Chemical Physics

Background:

• Tetrel bonds are crucial non-covalent interactions involving tetrel group elements (C, Si, Ge, Sn, Pb).
• Understanding tetrel bonding is essential for predicting molecular recognition and complex formation.

Purpose of the Study:

• To investigate the tetrel bonding capabilities of I₄Tt molecules with halide anions (X^-).
• To characterize the strength and nature of tetrel bonds in [I₄Tt···X^-] complexes using advanced computational methods.

Main Methods:

• Density functional theory (DFT) with ωB97X-D functional.
• Ab initio methods including Møller-Plesset perturbation theory (MP2) and coupled-cluster singles and doubles (CCSD).
• High-level coupled-cluster calculations with single, double, and perturbative triple excitations [CCSD(T)] for accurate interaction energies.

Main Results:

• Twenty-five [I₄Tt···X^-] complexes were analyzed, revealing diverse tetrel bond strengths.
• Weak-to-moderate tetrel bonds were observed in [I₄C···X^-] and some [I₄Tt···X^-] (Tt = Si, Sn) complexes.
• Dative tetrel bonds with significant interaction energies (-3.0 to -112.2 kcal mol^-1) and short Tt···X distances were found in 16 complexes.
• DFT (ωB97X-D) generally agreed with high-level theory, while MP2 provided misleading results for certain systems.
• Quantum Theory of Atoms in Molecules (QTAIM) and Independent Gradient Model (IGM) analyses elucidated the bonding environments.

Conclusions:

• The tetrel atom in I₄Tt effectively recognizes and binds halide anions through tetrel bonds.
• The strength and nature of tetrel bonds are highly dependent on the specific tetrel atom and halide anion involved.
• Computational methods provide valuable insights into non-covalent interactions, but method selection is critical for accurate predictions.