Small Ring Molecules Comprising 3-6 Boron Atoms: An Account on Synthesis, Structure, and Orbital Engineering.

Area of Science:

• Inorganic Chemistry
• Boron Chemistry
• Computational Chemistry

Background:

• Boron typically forms polyhedral structures due to electron deficiency, unlike carbon's ring systems.
• Traditional models suggested boron rings must be 3D, limiting exploration of planar structures.
• Recent advances in boron chemistry have focused on synthesizing novel ring systems.

Purpose of the Study:

• To highlight significant experimental and theoretical advancements in the synthesis of boron ring molecules.
• To discuss strategies for stabilizing planar or near-planar boron ring systems.
• To provide a comprehensive overview for the boron chemistry community on designing and synthesizing boron rings.

Main Methods:

• Experimental synthesis of boron ring molecules using transition metal templates and other approaches.
• Computational studies to understand structures, bonding, and develop electron counting rules.
• Analysis of stabilization strategies including transition metal/main group caps and Lewis bases.

Main Results:

• Synthesis of an almost planar B6-ring stabilized by a transition metal template.
• Stabilization of B3-, B4-, and B5-rings within transition metal coordination spheres.
• Uncovered diversity in structures and bonding of B3 and B4 rings, including redox reactions.

Conclusions:

• Planar boron rings are achievable targets, contrary to previous assumptions.
• Various stabilization strategies, including TM-templated synthesis and electronic control, enable the formation of flat boron systems.
• This work provides essential insights for designing and synthesizing diverse boron ring structures.