Fivefold Bonding in Cr(I) Dimer
This paper describes the synthesis and characterization of a Cr(I) dimer with a very short Cr-Cr distance. Computational studies support fivefold bonding between the chromium atoms. I have used this paper to introduce metal-metal multiple bonds and discuss the molecular orbital interactions of homonuclear diatomics including d-orbitals. More generally, it is a nice example to stimulate the discussion of what constitutes a bond and the various interpretations of bond order.