Fragmentation and Distortion of Terpyridine-Based Spin-Crossover Complexes on Au(111)

Spin-crossover complexes are attractive for their spin-switching functionality. However, only a few compounds have been found to remain intact in direct contact to metal surfaces. For the design of new spin crossover complexes, it is important to understand the mechanisms leading to fragmentation. Here, we investigate, using low-temperature scanning tunneling microscopy along with density functional theory calculations, two Fe(terpyridine)(2) complexes deposited on Au(111) by electrospray ionization with in-line mass selection. Only fragments of the first compound are observed on the surface, while the second compound is strongly flattened. On the basis of a detailed analysis of the adsorbates on the surface, possible mechanisms for the fragmentation and molecular distortion are proposed.