Bader's Topological Bond Path Does Not Necessarily Indicate Stabilizing Interaction-Proof Studies Based on the...

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Computational Chemistry

Background:

• Bader's quantum theory of atoms in molecules (QTAIM) defines bonded atoms by the presence of a bond path and bond critical point.
• This is generally assumed to indicate a stabilizing interaction within a molecular system.
• However, 'counterintuitive' bond paths challenge this assumption, particularly in endohedral complexes.

Purpose of the Study:

• To investigate whether topological bond paths in endohedral complexes necessarily indicate stabilizing interactions.
• To challenge the universal applicability of QTAIM's bond path criterion for stabilizing interactions.
• To provide evidence for repulsive guest-host interactions in endohedral complexes.

Main Methods:

• Utilized Bader's quantum theory of atoms in molecules (QTAIM) for topological analysis.
• Studied 24 noble gas (Ng) encapsulated within [3n]cyclophane (3≤n≤6) endohedral complexes.
• Performed geometry optimizations on guest@host complexes with small escape channels.

Main Results:

• Observed numerous counterintuitive bond paths in endohedral complexes, suggesting non-stabilizing interactions.
• Demonstrated spontaneous escape of guest species from host cages during geometry optimization.
• Found that topological bond paths do not always correlate with stabilizing interactions.

Conclusions:

• Topological bond paths, as defined by QTAIM, do not exclusively signify stabilizing interactions.
• The presence of guest-host repulsive forces can lead to counterintuitive bond paths in endohedral complexes.
• The spontaneous escape phenomenon provides strong evidence against the stabilizing nature of certain QTAIM-defined interactions.