Inducing Radicality in Gold‐Coordinated Porphyrinoids Through Precise Tip‐Induced Covalent Bond Dissociation

Abstract

ABSTRACT π‐Extended porphyrinoids are versatile platforms for the emerging field of π‐electron magnetism in conjugated systems. However, achieving controlled bond‐selective transformations that enable tuning of their electronic ground states remains a major challenge. Here, we propose a protocol for covalent bond dissociation in π‐extended porphyrinoids at carbonitrile‐Au substituents. By applying bias pulses with an STM tip positioned close to the molecule, the ligand can be selectively cleaved, resulting in chemisorption of the porphyrinoid onto the Au(111) surface. BR‐STM provides structural insights into the bonding configurations before and after the scission, while STS in combination with DFT+CASCI calculations reveals the impact of the cleavage on the molecule's electronic properties. Whereas the intact molecule exhibits a closed‐shell electronic structure, removal of the ligands induces a change in its electronic ground state, leading to the emergence of a Kondo resonance upon cleavage of the CN─Au ligands. In addition, DFT + vdW simulations show that carbonitrile─Au coordination weakens the carbon─carbon bond connecting the ligand to the molecular core, thereby facilitating its cleavage through tip‐induced manipulation. Overall, these results provide insights into the bonding nature of the carbonitrile─Au interaction and demonstrate how the bond scission induces a transition from closed‐shell to open‐shell states.