Geometric structures and electronic properties of Co2Ge10−/0: Anion photoelectron spectroscopy and quantum chemistry calculations

The structure and electronic properties of Co2Ge10− anion and its neutral counterpart were investigated by anion photoelectron spectroscopy and theoretical calculations. The experimental vertical detachment energy of Co2Ge10− was measured to be 2.86±0.08 eV. The lowest-energy isomer of Co2Ge10− is in a doublet state and has a cage-like structure with Cs symmetry, which can be constructed by a tetragonal bipyramid on top of a pentagonal bipyramid and these two bipyramid structures share a common Co atom. The most stable structure of neutral Co2Ge10 resembles its anionic counterpart and it is in a triplet state. The natural population analysis showed that the inner Co atom of both the anionic and neutral Co2Ge10 acquires negative charge from the neighboring Ge atoms. The outer Co atom has a larger spin moment than the inner Co atom, indicating that the magnetic moments of Co2Ge10−/0 are mainly contributed by the outer Co atom. Analyses of the density of states and molecular orbitals indicated that there are a few highly delocalized molecular orbitals in Co2Ge10−, which are mainly contributed by Ge 4s atomic orbitals.