[C ₆₀ Au] ⁺ : C ₆₀ ⁺ Au versus C ₆₀ Au ⁺

Single-molecule devices (SMDs) offer a transformative path beyond conventional electronics, leveraging the unique quantum properties of individual molecules. Fullerenes, particularly C₆₀, are highly attractive candidates for SMDs owing to their unique electronic properties and structural versatility. Gold is widely employed as an electrode material, making the C₆₀-Au interface a key determinant of device performance. However, the interaction nature between C₆₀ and gold, even for a single gold atom, remains elusive. Herein, we report the Ar-tagged infrared multiple photon dissociation spectrum of the [C₆₀Au]⁺ cluster aided with density functional theory calculations. Our results suggest that the configurations of the atop (η¹) site and the bridge site between two hexagons (η^2(6-6)) likely coexist for [C₆₀Au]⁺, with the η¹ configuration being slightly more favorable. Charge analysis reveals that C₆₀ accumulates more positive charges (η¹, +0.70 <i>e</i>; η^2(6-6), +0.66 <i>e</i>) and participates in the bonding with gold in the form of C₆₀⁺. Energy decomposition analysis combined with extended transition state-natural orbitals for chemical valence calculations reveal that the C₆₀⁺-Au interaction involves electron-sharing and dative bonding components, while in the neutral C₆₀Au complex there are only dative bonds. These findings offer molecular-level insights into metal-fullerene interactions and contribute to the fundamental basis for designing fullerene-based single-molecule devices.