Metal-Coordination Network vs Charge Transfer Complex: The Importance of the Surface

Contrary to expectations based on solution chemistry, scanning tunneling microscopy results show that, on a Ag(111) surface, the formation of a TTF-TCNE charge transfer complex is favored over an already existent Ag-TCNE coordination network. Density functional theory calculations show that the reason behind this apparent abnormal behavior relies on the much stronger interaction of the Ag adatoms with the Ag crystal when compared to TTF. These results demonstrate that the standard hierarchy of intermolecular interactions must be carefully revised for organic systems adsorbed on solid surfaces, which may have important consequences for the development of organic-based devices.