To Boldly Pass the Metal–Metal Quadruple Bond

The metal–metal quintuple bond: Minimizing the number of sterically demanding ligands increases the number of valence orbitals available to form metal–metal bonds. Following this concept, Power et al. have recently synthesized and structurally characterized a dinuclear chromium–chromium-bonded complex with one ligand per metal atom (see picture) featuring a metal–metal quintuple bond. Driving this concept to an extreme, even larger bond orders than five should be feasible.