O©Li₅F₅^2-: A Global Minimum with a Planar Pentacoordinate Oxygen

Area of Science:

• Inorganic Chemistry
• Computational Chemistry
• Quantum Chemistry

Background:

• Planar pentacoordinate oxygen (ppO) motifs are rare and theoretically challenging to stabilize.
• Previous research has explored various cluster structures, but confirmed examples of ppO are limited.

Purpose of the Study:

• To systematically investigate dianionic clusters (O©M5X52-) for viable planar pentacoordinate oxygen (ppO) motifs.
• To identify and characterize the structural, bonding, and electronic properties of potential ppO systems.

Main Methods:

• High-throughput computational screening across a wide combinatorial space of M (Li-Cs) and X (F-I) elements.
• Density Functional Theory (DFT) calculations for structural optimization and energy analysis.
• Analysis of bonding characteristics and magnetic responses.

Main Results:

• The starlike D5h-O©Li5F52- cluster was identified as the only true global minimum among the investigated structures.
• Detailed analyses confirmed that electrostatic interactions are the primary stabilizing force, rather than multicenter covalent bonding.
• The D5h-O©Li5F52- cluster represents the second confirmed system exhibiting planar pentacoordinate oxygen.

Conclusions:

• The D5h-O©Li5F52- cluster provides a new, experimentally verifiable example of planar pentacoordinate oxygen.
• This study demonstrates that ppO motifs can be achieved through strong electrostatic confinement.
• The findings open avenues for designing novel inorganic compounds with unique structural and electronic properties.