An Extended Rudolph Diagram: B₃H₅ and B₃H₆ Relate 3D-, 2D-, 1D-, and 0D-Boron Allotropes

Area of Science:

• Inorganic Chemistry
• Materials Science
• Theoretical Chemistry

Background:

• Boron's structural chemistry deviates from traditional sp, sp2, and sp3 hybridization models.
• Existing knowledge separates polyhedral boranes/3D allotropes from 2D borophene structures.

Purpose of the Study:

• To establish a unified framework connecting diverse boron structures.
• To elucidate the formation principles of borophenes and multilayer borophenes.
• To identify key boron clusters as building blocks for complex boron architectures.

Main Methods:

• Utilized an extended Rudolph diagram to correlate different boron structures.
• Investigated all-boron analogues of cyclopropenium cation (B3H5, B3H6+).
• Employed theoretical validation for the design principles of multilayer borophenes.

Main Results:

• Identified B3H5 and B3H6+ as crucial links between polyhedral boranes and borophenes.
• Demonstrated B3H6+ as a precursor for polyhedral boranes (e.g., B6H62-).
• Showcased planar B3H6+ and B3H5 as related to borophenes with hexagonal holes, enabling diverse stacking.

Conclusions:

• The study provides a unified view of boron structural chemistry.
• Electron sufficiency drives the formation of hexagonal holes and specific interlayer bonds in multilayer borophenes.
• The findings offer design principles for novel boron materials.