Atomically Dispersed Cobalt within a Bilayer of C60.

Individual cobalt atoms trapped within a bilayer of C60 have been produced by the deposition of Co atoms onto a C60 double layer supported on graphite. High-resolution scanning tunneling microscopy (STM) reveals two stable states of a single cobalt atom coordinated with three C60 molecules, which is denoted as (C60)3Co. The diffusion of the cobalt atoms within the C60 layers is highly limited, resulting in the effective capture of single cobalt atoms in the interstitial sites of the close-packed C60 layers. Density functional theory calculations show that the Co atom is located in the tetrahedral void between two close-packed C60 layers. The most stable configuration of (C60)3Co consists of two C60 molecules from the top layer with the third C60 from the bottom layer. A less stable configuration of (C60)3Co where all three C60 molecules are from the top layer was also observed at room temperature.