How Thermodynamic, Electronic, and Steric Factors Influence Mesitylcopper Oligomers
D P Ngan Le1, Michael Stollenz2, Samer Gozem1
1Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, United States.
The Journal of Physical Chemistry. A
|October 24, 2025
Summary
Mesitylcopper (CuMes) aggregation is driven by electronic interactions between copper d orbitals and mesityl pi orbitals. Mid-sized oligomers (n=4-5) represent the most stable structures due to a balance of electronic, steric, and entropic factors.
Area of Science:
- Organometallic Chemistry
- Computational Chemistry
Background:
- Mesitylcopper (CuMes) is a key organocopper reagent in synthesis.
- CuMes exists as cyclic tetrameric or pentameric oligomers ([CuMes]n, n=4, 5).
- The electronic and thermodynamic drivers of CuMes aggregation remain unclear.
Purpose of the Study:
- Investigate the electronic, structural, and thermodynamic forces behind CuMes aggregation.
- Utilize computational methods to analyze monomeric and oligomeric CuMes species.
- Determine the factors governing the stability of different [CuMes]n oligomers.
Main Methods:
- Density Functional Theory (DFT) calculations were employed.
- Studied monomeric [CuMes] and oligomers [CuMes]n (n=2-7).
- Analyzed electronic orbital mixing, bonding, steric, and entropic effects.
Main Results:
- Strong electronic driving force for aggregation due to Cu d-Mes π orbital mixing in oligomers (n≥3).
- Mesityl groups act as bridging ligands in stable oligomers, optimizing orbital overlap.
- Midsized oligomers (n=4-5) exhibit optimal stability by balancing electronic, steric, and entropic factors.
Conclusions:
- DFT calculations elucidate the aggregation behavior of mesitylcopper.
- Electronic factors, specifically Cu-Mes orbital mixing, are primary drivers of CuMes oligomerization.
- Thermodynamic stability of [CuMes]n is determined by a complex interplay of electronic, steric, and entropic contributions, favoring midsized aggregates.
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