Saturnenes Like Th@Au₆ D_6h: Ring-Current Evidence for Au Au Bonding Along the Gold Ring

The electronic structure and stability of M '@M-n systems is considered using DFT. The metal atom M ' is a rare earth, actinide, or a d transition metal, and M is a coinage (Group 11) metal. The sigma aromaticity along the M-n ring is emphasized. As a further indicator for it, the magnetically induced currents along the ring are studied, and found to be considerably larger than the aromatic pi currents in benzene. A name saturnenes is suggested for these atom-inside-ring systems. Attention is also called for the known analogous stick-inside-ring systems.