Do Planar Tetracoordinate Fluorine Atoms Exist? Revisiting a Theoretical Prediction

Area of Science:

• Inorganic Chemistry
• Computational Chemistry
• Quantum Chemistry

Background:

• Recent studies proposed the existence of planar tetracoordinate fluorine (ptF) atoms.
• These proposals were based on high-level ab initio calculations.

Purpose of the Study:

• To rigorously re-examine the existence of planar tetracoordinate fluorine (ptF) atoms.
• To investigate the stability of proposed ptF structures in various cationic complexes.

Main Methods:

• High-level ab initio methods, including coupled-cluster singles and doubles with perturbative triples (CCSD(T)).
• Utilized large basis sets for accurate electronic structure calculations.
• Employed Density Functional Theory (DFT) to assess potential discrepancies.

Main Results:

• The planar structures of FIn4+, FTl4+, FGaIn3+, FIn2Tl2+, FIn3Tl+, and FInTl3+ were identified as transition states, not minimum energy states.
• Density Functional Theory (DFT) was found to overestimate cavity size, leading to erroneous conclusions about ptF atoms.
• The preference for non-planar structures was not attributed to the pseudo Jahn-Teller effect, and spin-orbit coupling did not alter the findings.

Conclusions:

• The existence of planar tetracoordinate fluorine (ptF) atoms in the studied cations is not supported by accurate computational methods.
• Accurate theoretical investigations suggest that ptF atoms are unlikely to exist under typical conditions.
• The formation of a sufficiently large cavity by group 13 elements could potentially allow for ptF atom existence.