PrB7−: A Praseodymium‐Doped Boron Cluster with a PrII Center Coordinated by a Doubly Aromatic Planar η7‐B73− Ligand

Abstract

AbstractThe structure and bonding of a Pr‐doped boron cluster (PrB7−) are investigated using photoelectron spectroscopy and quantum chemistry. The adiabatic electron detachment energy of PrB7− is found to be low [1.47(8) eV]. A large energy gap is observed between the first and second detachment features, indicating a highly stable neutral PrB7. Global minimum searches and comparison between experiment and theory show that PrB7− has a half‐sandwich structure with C6v symmetry. Chemical bonding analyses show that PrB7− can be viewed as a PrII[η7‐B73−] complex with three unpaired electrons, corresponding to a Pr (4f26s1) open‐shell configuration. Upon detachment of the 6s electron, the neutral PrB7 cluster is a highly stable PrIII[η7‐B73−] complex with Pr in its favorite +3 oxidation state. The B73− ligand is found to be highly stable and doubly aromatic with six delocalized π and six delocalized σ electrons and should exist for a series of lanthanide MIII[η7‐B73−] complexes.