Surface-Mediated Catalytic Dechlorination and Spin-State Modulation of ClFePc on Au(111)

Interactions between molecules and surfaces are crucial in modern surface science. In particular, surfaces catalyze molecular reactions and modulate molecular spin states. In this article, we investigate the adsorption behaviors and electronic structures of chloro-iron phthalocyanine (ClFePc) on Au(111). Combining ultrahigh vacuum scanning tunneling microscopy experiments with density functional theory calculations, we found indications of surface-catalyzed dechlorination. Our findings reveal that the adsorption behavior of ClFePc is determined by its adsorption direction. ClFePc in the Cl-up (Cl pointing to the vacuum) configuration exhibits stable adsorption on the Au(111) surface. Conversely, the Cl-down (Cl pointing to the substrate) configuration is unstable, resulting in the dissociation of the Cl–Fe bond due to interactions with the Au(111) surface. Through scanning tunneling spectroscopy analysis, we further investigate the Kondo resonance features and spin characteristics. Notably, following dechlorination, the spin-state transitions from S = 3/2 to 1. This study provides profound insights into the surface-molecule interaction and its application in modulating magnetic properties.