Accurate Calculation of Electron Paramagnetic Resonance Parameters for Molybdenum Compounds

Area of Science:

• Inorganic chemistry
• Computational chemistry
• Quantum chemistry

Background:

• Paramagnetic molybdenum compounds are vital in inorganic chemistry and metalloenzyme catalysis.
• Electron paramagnetic resonance (EPR) spectroscopy is key for studying their electronic structure.
• Accurate quantum chemical calculations are needed to interpret EPR data.

Purpose of the Study:

• To present a database of Mo(V) complexes with defined structures and EPR parameters.
• To investigate optimal quantum chemical protocols for predicting 95Mo hyperfine coupling constants (HFCs) and g-values.
• To assess the performance of various density functional theory (DFT) functionals.

Main Methods:

• Utilized the exact-2-component (X2C) Hamiltonian with unmodified segmented all-electron relativistically contracted (SARC) basis sets.
• Evaluated the performance of different DFT functionals, including double-hybrid and global hybrid functionals.
• Compared DFT-derived EPR parameters with coupled cluster theory (DLPNO-CCSD) results.

Main Results:

• Converged results for HFCs and g-values were obtained using X2C and SARC basis sets.
• Double-hybrid and global hybrid functionals showed superior performance for 95Mo HFCs, with PBE0-DH being the best.
• DFT proved to be the method of choice for these Mo compounds, outperforming coupled cluster theory in some aspects.
• PBE0-DH was also a top performer for g-tensors, recommended for both valence and core properties.

Conclusions:

• Optimal quantum chemical protocols involving X2C and specific DFT functionals (especially PBE0-DH) enable accurate prediction of EPR parameters for molybdenum compounds.
• DFT, particularly with PBE0-DH, is a reliable and efficient method for studying the electronic structure of these systems.