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Nickel-catalyzed alkyl coupling reactions: evaluation of computational methods
Lawrence M Pratt1, Stewart Voit, Fabian N Okeke
1Department of Chemistry, Fisk University, 1000 17th Avenue North, Nashville, Tennessee 37208, USA. lpratt@fisk.edu
The Journal of Physical Chemistry. A
|March 1, 2011
Summary
Density Functional Theory (DFT) methods were assessed for nickel-catalyzed coupling reactions. M06 and PBE1PBE functionals accurately modeled reaction geometries and transition states, identifying nucleophilic attack as the rate-limiting step.
Area of Science:
- Computational Chemistry
- Organometallic Chemistry
- Catalysis
Background:
- Nickel-catalyzed coupling reactions are crucial in organic synthesis.
- Accurate theoretical modeling is essential for understanding reaction mechanisms and optimizing catalysts.
- Previous studies have shown varying success with different Density Functional Theory (DFT) methods for transition metal catalysis.
Purpose of the Study:
- To evaluate the performance of six DFT methods (B3LYP, M06, M06L, M062X, MPW1K, PBE1PBE) for modeling nickel-catalyzed coupling reactions.
- To identify the most reliable DFT functionals for predicting reaction geometries and transition states.
- To determine the rate-determining step of the investigated nickel-catalyzed coupling reaction.
Main Methods:
- DFT calculations were performed using B3LYP, M06, M06L, M062X, MPW1K, and PBE1PBE functionals.
- High-level coupled-cluster calculations (CCSD(T)) were used for single-point energy evaluations at DFT-optimized geometries.
- Second-order Møller–Plesset perturbation theory (MP2) and coupled-cluster singles and doubles (CCSD) methods were also employed for single-point energy calculations.
Main Results:
- B3LYP, M06, and PBE1PBE functionals provided the most accurate ground-state geometries based on CCSD(T)//DFT single-point energies.
- M06 functional showed comparable or superior performance to B3LYP and PBE1PBE for transition state energy calculations.
- The nucleophilic attack of a L(2)NiR anion on an alkyl halide was identified as the rate-determining step.
Conclusions:
- M06 and PBE1PBE are recommended DFT functionals for modeling nickel-catalyzed coupling reactions due to their accuracy in geometry and transition state predictions.
- Understanding the rate-determining step provides insights for catalyst design and reaction optimization.
- The study highlights the importance of method selection in computational chemistry for reliable mechanistic studies.
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