An actinocene is a type of metallocene compound that contains an element from the actinide series. The typical structure is a sandwich compound, with two cyclooctatetraenyl dianions (cot, which is C
8H2−
8) bound to an actinide-metal center (An) in the oxidation state IV, with the resulting general formula An(C8H8)2
The most studied actinocene is uranocene, U(C8H8)2.
The actinide-cyclooctatetraenyl bonding was shown by computational chemistry to be mainly due to mixing of actinide 6d orbitals into ligand π-orbitals and therefore donation of electronic charge to the actinide, with a smaller such interaction involving the actinide 5f orbitals.
Other actinocenes include protactinocene (Pa(C8H8)2), thorocene (Th(C8H8)2), neptunocene (Np(C8H8)2), and plutonocene (Pu(C8H8)2).
Sandwiched M(C8H8)2 compounds (actinocenes and lanthanocenes) exist for M = (Nd, Tb, Pu, Pa, Np, Th, U and Yb).