Trihapto Ligation of a Borirene to a Single Metal Atom: A Heterocyclic Analogue of the η 3 ‐Cyclopropenyl Ligand

The first example of a complex containing an η(3)-coordinated borirene ligand bound to a single metal atom was prepared by photolytic transfer of an arylborylene ligand to diphenylacetylene and loss of three CO ligands from the precursor. The η(3)-borirene complex possesses a chromium(0) atom which is also bound to one phenyl group in an η(6) fashion. The complex was isolated in 15% yield along with the corresponding metal-free borirene, which was isolated in 62% yield. The bonding between the chromium center and the borirene ring was studied computationally by DFT methods.