Observation of Orbital-Resolved Conductance in a Single-Molecule Metal–Metal Interaction Channel

The exploration of unique metallophilic interactions, a pivotal category of intermolecular interactions that govern material properties and reactivity, is crucial for deciphering the role of metal atomic orbitals in their formation and uncovering their fundamental characteristics. However, due to their inherently subtle and delicate nature, these interactions remain exceptionally challenging to detect and characterize. Here, we present a method of utilizing metallophilic interactions to build stable graphene–molecule–graphene single-molecule junctions through molecular engineering. Real-time electrical measurements reveal that the metal atomic orbital contributions in various metal–metal interactions originate from the hybridization of different angular components of intermetallic d and s orbitals (dz2–s/dxy–s), a conclusion further corroborated by theoretical calculations. Distinct overlaps between intermetallic orbitals give rise to diverse molecular configurations, leading to corresponding orbital-resolved conductance. Furthermore, we establish the relationship between the orbital interaction and experimental transition activation energy through counterion- and metal-dependent measurements. This work uncovers the underlying mechanism of metal–metal interactions, bridges the gap between covalent bonds and weak interactions, and extends the research scope of molecular electronics.