New Molecular Geometries with Pentagonal-Pyramidal Structure

Area of Science:

• Computational chemistry
• Theoretical chemistry
• Quantum chemistry

Background:

• The benzene dication (C6H6^2+) exhibits a unique pentagonal-pyramidal geometry.
• Understanding the electronic structure and stability of dicationic species is crucial in molecular science.

Purpose of the Study:

• To design novel molecular ions with similar pentagonal-pyramidal structures to the benzene dication.
• To investigate the stability and geometric preferences of these new dicationic species.

Main Methods:

• Global minimum (GM) searches were employed to identify stable structures.
• Density Functional Theory (DFT) computations were utilized to analyze the electronic properties and geometries.

Main Results:

• Several new dicationic species, including C5H6Si^2+, C5H5N^2+, C5H5P^2+, C5H6B^+, and C5H6Al^+, were computationally designed.
• All designed ions, except for the pyridine dication, adopted a pentagonal-pyramidal geometry.
• Eight valence electrons were found to stabilize these structures, analogous to the benzene dication.

Conclusions:

• The study demonstrates that eight valence electrons can stabilize pentagonal-pyramidal structures in dicationic species with penta- or hexacoordinated main group elements.
• The phosphorine dication is highlighted as a promising candidate for experimental realization and detection, drawing parallels with previous benzene dication research.