Benchmark Study of Density Functional Theory Methods in Geometry Optimization of Transition Metal-Dinitrogen...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Inorganic Chemistry

Background:

• Accurate geometric optimization of transition metal-dinitrogen complexes is crucial for understanding their reactivity.
• Density Functional Theory (DFT) offers various methods, but their precision for these systems requires evaluation.

Purpose of the Study:

• To benchmark seven Density Functional (DF) methods for optimizing transition metal-dinitrogen complex geometries.
• To identify the most precise theoretical method using experimental X-ray data.

Main Methods:

• Selected seven DFT functionals (B3LYP-D3(BJ), BP86-D3(BJ), PBE0-D3(BJ), ωB97X-D, M06, M06-L, TPSSh-D3(BJ)) with the def2-SVP basis set.
• Evaluated performance against experimental X-ray data for 42 transition metal-dinitrogen compounds from the CCDC.
• Calculated root-mean-square deviation (RMSD) and bond lengths (N-N, M-N) for comparison.

Main Results:

• Minnesota functionals (M06, M06-L) and TPSSh-D3(BJ) demonstrated good performance with lower RMSD values.
• M06-L showed the lowest absolute errors in N-N and M-N bond lengths, indicating superior accuracy.
• The use of a higher-level def2-TZVP basis set had a negligible impact on RMSD compared to def2-SVP.

Conclusions:

• M06-L is the most reliable functional for optimizing the geometry of transition metal-dinitrogen complexes.
• The chosen DFT methods, particularly Minnesota functionals and TPSSh-D3(BJ), offer accurate geometric predictions.
• Basis set choice has minimal influence on the relative performance of these DFT methods for this application.