Self-contained Kondo effect in single molecules

Kondo coupling of f and conduction electrons is a common feature of f-electron intermetallics. Similar effects should occur in carbon ring systems (metallocenes). Evidence for Kondo coupling in Ce(C8H8)(2) (cerocene) and the ytterbocene (Cp2Yb)-Yb-*(bipy) is reported from magnetic susceptibility and L-III-edge x-ray absorption spectroscopy. These well-defined systems provide a new way to study the Kondo effect on the nanoscale, should generate insight into the Anderson Lattice problem, and indicate the importance of this often-ignored contribution to bonding in organometallics.