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A High-Fidelity Molecular Model of the Cu(111) Repeating Unit
Andrew W Beamer1, Kelsey S Zimmerman1, Joshua A Buss1
1Willard Henry Dow Laboratory, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States.
Journal of the American Chemical Society
|April 30, 2026
Summary
A tricopper molecular cluster mimics the behavior of a Cu(111) surface for carbon monoxide (CO) adsorption and dihydrogen (H2) activation. This cluster-surface analogy provides a precise model for studying heterogeneous catalysis mechanisms.
Area of Science:
- Heterogeneous Catalysis
- Surface Science
- Inorganic Chemistry
- Computational Chemistry
Background:
- Understanding dynamic surface processes is crucial for heterogeneous catalysis.
- Atomistic mechanisms are often obscured by material structural variations and differing reaction/characterization conditions.
- The cluster-surface analogy offers a potential solution for studying surface chemistry in a controlled manner.
Purpose of the Study:
- To validate the cluster-surface analogy using a low-valent tricopper cluster (1) as a model for Cu(111).
- To investigate small molecule activation, specifically carbon monoxide (CO) adsorption and dihydrogen (H2) dissociative adsorption.
- To compare the reactivity and energetics of the molecular cluster with the established behavior of the Cu(111) surface.
Main Methods:
- Synthesis and characterization of a low-valent tricopper molecular cluster (1).
- Variable temperature Nuclear Magnetic Resonance (NMR) spectroscopy using 13CO to study CO binding thermodynamics.
- Kinetic analysis to determine activation parameters for H2 dissociative adsorption on the cluster.
Main Results:
- The tricopper cluster (1) reversibly binds CO with favorable enthalpy but unfavorable entropy, resulting in marginally endergonic adsorption at room temperature.
- Cluster (1) exhibits oxidative addition (chemisorption) of H2, mirroring the behavior of the Cu(111) surface.
- The activation enthalpy for H2 adsorption on the cluster (8.4 ± 0.5 kcal/mol) closely matches literature values for Cu(111) (6.0–12.4 kcal/mol).
Conclusions:
- A trinuclear copper cluster can accurately reproduce the energetics of small molecule binding and activation observed on a bulk Cu(111) surface.
- This study validates the cluster-surface analogy, demonstrating its utility for studying heterogeneous catalysis.
- The findings pave the way for using atomically precise molecular clusters to investigate complex surface processes.
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