Photoelectron spectroscopy and ab initio study of boron-carbon mixed clusters: CB9- and C2B8-

We performed a joint photoelectron spectroscopy and ab initio study of two carbon-doped boron clusters, CB9- and C2B8-. Unbiased computational searches revealed similar global minimum structures for both clusters. The comparison of the experimentally observed and theoretically calculated vertical detachment energies revealed that only the global minimum structure is responsible for the experimental spectra of CB9-, whereas the two lowest-lying isomers of C2B8- contribute to the experimental spectra. The planar distorted wheel type structures with a single inner boron atom found for CB9- and C2B8- are different from the quasi-planar structure of B-10(-), which consists of two inner atoms and eight peripheral boron atoms. The adaptive natural density partitioning chemical bonding analysis revealed that CB9- and C2B8 clusters exhibit pi aromaticity and sigma antiaromaticity, which is consistent with their planar distorted structures. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4770231]