Boron-Boron Multiple Bonding: From Charged to Neutral and Back Again

The area of boronboron multiple bonding has fascinated many researchers over the years. However, the apparent difficulty of this chemistry meant that for decades the number of compounds in this category was very limited. In 2007, Robinson and co-workers presented a synthesis of a neutral compound with a boronboron double bond. In our laboratories we have since extended this by adding four new, selective routes to these diborene compounds, as well as isolating the first compound with a boronboron triple bond. Herein a history of accomplishments in noncarbon main-group multiple bonding and the base stabilization of allotropes of main-group atoms is given. This is followed by an account of the recent progress made in the area of boronboron multiple bonding.