Building a Quintuple Bond

Since 1964, chemists have tried without success to synthesize molecules in which the constituent atoms have bond order (that is, the number of bonds between a pair of atoms) greater than four. In his Perspective, [Frenking][1] discusses results reported in the same issue by [ Nguyen et al. ][2] in which fivefold bonding between chromium atoms has been achieved. The synthesis was made possible through the use of functional groups that bond with chromium in such a way that the chromium atoms can form quintuple bonds with each other. This opens the way for more novel multiple bond chemistry and will provide plenty of food for thought for experimentalists and theoreticians alike. [1]: http://www.sciencemag.org/cgi/content/full/310/5749/796 [2]: http://www.sciencemag.org/cgi/content/short/310/5749/844