What is "diboryne"

A diboryne in chemistry is a chemical compound containing a boron-to-boron triple bond. Such compounds are of fundamental importance in the study of chemical bonding, though only few have been reported. A diboryne stabilized by two carbon monoxide groups (OCBBCO) was reported isolated in matrix isolation in 2002. A diboryne stable at room temperature with two N-heterocyclic carbene (NHC) units was reported in 2012. In terms of qualitative MO theory the B molecule is expected to have a single bond but with NHC ligands the third excited state yields a triple bond.