Direct molecular-level understanding of heterogeneous catalysis remains intrinsically challenging because the active sites cannot easily be isolated and studied individually, while well-established concepts from molecular catalysis are often difficult to translate to processes on the surface.^[1] Transition-metal clusters have therefore emerged as important molecular models for heterogeneous catalysts by reproducing the coordination environments around active sites in processes such as hydrogen-evolution reaction (HER)^[2] and nitrogen oxide (NO_x) reduction.^[3] These systems reflect not only structural features but also functional behavior of catalytic surfaces, making them highly valuable in elucidating mechanisms and potential intermediates.

Herein, we propose a new family of heterometallic clusters as a molecular framework that, instead of mimicking surface active sites only structurally, incorporates the key functional characteristics of highly reactive surfaces in heterogeneous catalysis. Our trimetallic {Re₂Fe} clusters possess one accessible and reactive Fe center together with two Re metal cores which are supported by two μ-Dipp-imido fragments (Dipp = 2,6-diisopropylphenyl). Direct metal-metal bonds, along with multiple terminal and bridging imido moieties, render these clusters structurally rigid over multiple redox states. Gram-scale synthesis of the cluster enabled investigation of its rich redox chemistry and the accessibility of the Fe active site through coordination of different ligands. Furthermore, preliminary studies revealed promising catalytic activity in the conversion of phosphonium ylides to olefins.

[1] Robert Schlögl, Angewandte Chemie International Edition, 2015, 54, 3465-3520

[2] Lauren T. Feden, Shatha Alabbad, Manuraj Kallumkal, Jan-Niklas Boyn, Gwendolyn A. Bailey, Journal of the American Chemical Society, 2025, 147, 36686-36696.

[3] Andrew W. Beamer, Joshua A. Buss, Angewandte Chemie International Edition, 2025, 64, e202424772.