Local Electronic Properties of Titanocene Chloride Dimer Molecules on a Metal Surface

We have examined the local electronic behavior of titanocene chloride dimer molecules, [Cp2TiCl]2 (Cp = C5H5), on Au(111) using both scanning tunneling microscopy (STM) and density functional theory (DFT). Isolated dimeric molecules are seen to decorate gold step edges at low surface coverages and two coexisting monolayer phases are observed at higher coverages. Differential conductance STM spectroscopy shows a variety of structure in the electronic local density of states for single molecules and for the two monolayer phases. DFT calculations modeling an isolated titanocene chloride dimer do not reproduce the wide variations seen in spectral density, suggesting that a fraction of titanocene dimers break apart into metallocene monomers on the Au(111) surface and display magnetic behavior.