Bridges and Vertices in Heteroboranes

Area of Science:

• Inorganic Chemistry
• Computational Chemistry
• Boron Chemistry

Background:

• Main group atoms (X) in boranes can act as bridges or vertices.
• Distinguishing between these roles is crucial for understanding cluster structure and bonding.

Purpose of the Study:

• To develop a computational approach for differentiating the bridging vs. vertex roles of main group atoms in boranes.
• To analyze the electronic contributions of these atoms to the skeletal electron count.

Main Methods:

• Utilized Density Functional Theory (DFT) to optimize model [BnHn]2- fragments.
• Compared experimental borane cluster fragments with DFT-derived exemplars.
• Quantified the 'verticity' of main group atoms within the cluster framework.

Main Results:

• Identified the main group atom (X) as predominantly acting as a vertex in most studied (hetero)boranes.
• Quantified the 'verticity' of atom X to be approximately 60-65%.
• Demonstrated that radial electron contribution from X is more significant than tangential contribution.

Conclusions:

• Established a robust method for characterizing the structural role of main group atoms in borane clusters.
• Highlighted the importance of radial electron donation from heteroatoms in determining cluster stability and electronic properties.
• Provided a new perspective on bonding and structure in complex boron-based inorganic compounds.