Boron-made N2: Realization of a B≡B Triple Bond in the B2Al3- Cluster.

Until now, all B equivalent to B triple bonds have been achieved by adopting two ligands in the L -> B equivalent to B <- L manner. Herein, we report an alternative route of designing the B equivalent to B bonds based on the assumption that by acquiring two extra electrons, an element with the atomic number Z can have properties similar to those of the element with the atomic number Z+2. Specifically, we show that due to the electron donation from Al to B, the negatively charged B equivalent to B kernel in the B2Al3- cluster mimics a triple N equivalent to N bond. Comprehensive computational searches reveal that the global minimum structure of B2Al3- exhibits a direct B-B distance of 1.553 angstrom, and its calculated electron vertical detachment energies are in excellent agreement with the corresponding values of the experimental photoelectron spectrum. Chemical bonding analysis revealed one sigma and two pi bonds between the two B atoms, thus confirming a classical textbook B equivalent to B triple bond, similar to that of N-2.