Author: ["Sason Shaik","David Danovich","Wei Wu","Peifeng Su","Henry S. Rzepa","Philippe C. Hiberty"]
CITE.CC academic search helps you expand the influence of your papers.
Abstract
Triple bonding is conventionally considered to be the limit for multiply bonded main group elements, despite higher metal–metal bond orders being frequently observed for transition metals and lanthanides/actinides. Here, using high-level theoretical methods, we show that C2 and its isoelectronic molecules CN+, BN and CB− (each having eight valence electrons) are bound by a quadruple bond. The bonding comprises not only one σ- and two π-bonds, but also one weak ‘inverted’ bond, which can be characterized by the interaction of electrons in two outwardly pointing sp hybrid orbitals. A simple way of assessing the energy of the fourth bond is proposed and is found to be ~12–17 kcal mol−1 for the isoelectronic species studied, and thus stronger than a hydrogen bond. In contrast, the analogues of C2 that contain higher-row elements, such as Si2 and Ge2, exhibit only double bonding. The bonding order of multiply bonded main-group elements is conventionally thought to be limited to triple bonds. Now, using high-level theoretical methods, it is shown that C2 and its isoelectronic molecules CN+, BN and CB− are quadruply bonded, featuring not only one σ - and two π-bonds, but also one weak ‘inverted’ bond.
Cite this article
Shaik, S., Danovich, D., Wu, W. et al. Quadruple bonding in C2 and analogous eight-valence electron species. Nature Chem 4, 195–200 (2012). https://doi.org/10.1038/nchem.1263