Improving a Methane C-H Activation Complex by Metal and Ligand Alterations from Computational Results
Dragan B Ninković1,2, Salvador Moncho1, Predrag Petrović1
1Department of Chemistry, Texas A&M University at Qatar, P.O. Box 23874 Doha, Qatar.
Inorganic Chemistry
|March 22, 2023
Summary
Vanadium complexes show promise for activating methane's C-H bonds, with V(V) exhibiting the lowest activation barrier. Ligand modification further enhances catalytic performance.
Area of Science:
- Organometallic Chemistry
- Catalysis
- Computational Chemistry
Background:
- Titanium complexes can activate C-H bonds under mild conditions.
- Methylidene complexes are valuable synthetic intermediates.
- Exploring low-cost 3d transition metals is crucial for sustainable catalysis.
Purpose of the Study:
- To investigate methane C-H bond activation using various 3d transition metal complexes.
- To evaluate the potential of vanadium complexes for methane activation and methylidene tautomerization.
- To assess the impact of ligand modification on catalytic activity.
Main Methods:
- Density Functional Theory (DFT) calculations were employed.
- A series of isoelectronic and isocharged complexes with scandium, titanium, vanadium, and chromium were studied.
- Ligand modifications, including replacing nitrogen with phosphorus in the PNP ligand, were explored.
Main Results:
- Vanadium(IV) and Vanadium(V) complexes demonstrate significant potential for methane C-H bond activation.
- The V(V) complex exhibits a low activation barrier (16.6 kcal/mol) and a moderate tautomerization barrier (29.8 kcal/mol).
- Scandium and chromium complexes showed poor performance due to high barriers or overstabilization of intermediates.
Conclusions:
- Vanadium complexes are promising catalysts for methane C-H activation.
- Ligand modification, particularly the P-based analog of PNP, can further reduce reaction barriers, enhancing catalytic efficiency.
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