The structures of cyclic dihydronium cations.

Area of Science:

• Chemistry
• Materials Science
• Computational Chemistry

Background:

• Recent experiments identified novel cyclic hydronium di-cations, (H14O6)2+ and (H18O8)2+, within crystal structures.
• These species were observed as four- and six-member cyclic structures for (H14O6)2+, and an eight-member structure for (H18O8)2+.

Purpose of the Study:

• To investigate the stability of these cyclic hydronium di-cations as independent species in the absence of crystal stabilization.
• To determine the energetic favorability and optimized structures of these novel ions using theoretical methods.

Main Methods:

• Quantum mechanical density functional theory (DFT) calculations were employed.
• Theoretical optimization of molecular geometries for the identified hydronium di-cations was performed.
• Atomic charges were calculated for both crystal and optimized geometries.

Main Results:

• The study confirms that the doubly charged cyclic hydronium structures are energetically stable as independent species.
• The four-member cyclic isomer of (H14O6)2+ demonstrates greater binding energy compared to the six-member isomer.
• Optimized structures and atomic charges for all three cyclic hydronium di-cations were determined.

Conclusions:

• Cyclic hydronium di-cations, including (H14O6)2+ and (H18O8)2+, possess inherent stability independent of their crystalline environment.
• The findings suggest potential for these novel species to exist in other phases, such as solution or gas phase.
• The theoretical characterization provides a foundation for further experimental and computational studies of these unique ions.