PNNL

Abstract

We demonstrated in our joint photoelectron spectroscopic and ab initio study that wheel-type structures with a boron ring are not appropriate for designing planar molecules with a hypercoordinate central carbon on the example of CB8, and CB8 clusters. According to our chemical bonding model, in the wheel type structures the central atom is involved in delocalized bonding, while peripheral atoms are involved in both delocalized bonding and 2c-2e -bonding. Since carbon is more electronegative than boron it favors peripheral positions where it can participate in 2c-2e -bonding. To design a chemical species with a central hypercoordinate carbon atom, one should consider electropositive ligands, which would have lone pairs instead of 2c-2e peripheral bonds. We presented a chemical bonding model capable of rationalizing and predicting structures either with a boron ring or a central planar carbon. This represents the first step toward rational design of nano- and subnano-structures with tailored properties.