Accurate calculation of spin-state energy gaps in Fe(III) spin-crossover systems using density functional methods

Area of Science:

• Materials Science
• Computational Chemistry
• Inorganic Chemistry

Background:

• Iron(III) complexes are promising spin crossover (SCO) materials due to their air stability, unlike oxidizable iron(II) complexes.
• Accurate prediction of spin-state energy gaps is crucial for designing effective SCO systems.

Purpose of the Study:

• To systematically evaluate the performance of various exchange-correlation functionals for predicting SCO properties in Fe(III) complexes.
• To identify reliable computational methods for screening and designing new Fe(III)-based SCO materials.

Main Methods:

• A dataset of 24 hexacoordinated Fe(III) complexes was used for benchmarking.
• The accuracy of several exchange-correlation functionals was assessed for predicting high-spin (S = 5/2) and low-spin (S = 1/2) energy gaps.
• The B3LYP* functional was specifically evaluated for its predictive capabilities.

Main Results:

• The B3LYP* functional demonstrated excellent accuracy in predicting spin-state energy gaps for Fe(III) complexes.
• B3LYP* effectively distinguished between low-spin and high-spin Fe(III) complexes across various temperatures.
• A versatile Fe(III) compound with tunable SCO properties was identified by modifying a single axial ligand.

Conclusions:

• B3LYP* is a reliable and accurate computational tool for screening novel spin crossover systems with tailored properties.
• This work provides a validated approach for the rational design of Fe(III)-based SCO materials.