Here we report a recent joint experimental photoelectron spectroscopy (PES) and quantum chemical calculations study in our group: observation of highly stable and symmetrical lanthanide octa-boron inverse sandwich clusters-La2B8- and Pr2B8-.
PES spectra showed simple patterns of these two clusters, suggesting highly symmetric structures. Quantum chemical calculations revealed that both clusters possess inverse sandwich structures with two Ln atoms sandwiching the B8 ring, being the first inverse sandwiches observed for lanthanide boride complexes. By further chemical bonding analysis, we found a strong (d-p) π and (d-p) δ bonding is vital to stabilize these systems. Due to the unpaired f electrons in the systems and similarities of Lanthanide elements, these inverse sandwich structures can be viewed as motifs to design perspective magnetic materials, such as 1D nanowires.