Observation of Single Dinuclear Metal-Complex Molecules Using Scanning Tunneling Microscopy

We report a scanning tunneling microscopy (STM) investigation of a dinuclear organometallic molecule, trans-[Cl(dppe)₂Ru(C≡C)₆Ru(dppe)₂Cl] (Ru2), absorbed on a Au(111) surface; this molecule is a potential candidate for use in molecular quantum-dot cellular automata (QCA) devices. Isolated Ru2 molecules were observed under ultra-high-vacuum conditions. Submolecular structure was clearly discernible in the STM images, with a bright feature corresponding to each of the two Ru−ligand complexes within the Ru2 molecule. Rotation and translation of the Ru2 molecules were observed to be induced by the STM tip under some tunneling conditions.