Peculiar Differences between Two Copper Complexes Containing Similar Redox-Active Ligands: Density Functional and
Luca Gerhards1, Marco Werr2, Olaf Hübner2
1Institute of Physics, Carl von Ossietzky Universität Oldenburg, Carl-von-Ossietzky-Street 9-11, Oldenburg 26129, Germany.
Inorganic Chemistry
|December 29, 2023
Summary
This study reveals significant electronic structure differences in copper complexes with modified redox-active ligands. A multiconfigurational approach accurately describes copper
Area of Science:
- Inorganic Chemistry
- Computational Chemistry
- Materials Science
Background:
- Redox-active ligands in transition metal complexes enable multiple electronic states.
- Understanding these electronic structures is crucial for designing novel materials.
Purpose of the Study:
- To investigate the electronic structures of two copper complexes with urea azine ligands.
- To identify discrepancies in electronic configurations influenced by ligand modification (NCH3 vs. S atom).
- To evaluate the efficacy of different computational methods in describing these systems.
Main Methods:
- Synthesis and experimental characterization of two mononuclear copper complexes.
- Application of Density Functional Theory (DFT) with various functionals (B3LYP, TPSSh, CAM-B3LYP).
- Utilizing multiconfigurational approaches, including Complete Active Space Self-Consistent Field (CASSCF) and Multireference Perturbation Theory (MRPT).
Main Results:
- Experimental data showed distinct electronic structures for the two complexes in solution and solid states.
- Standard DFT methods failed to explain the observed spectroscopic anomalies.
- Multireference methods correctly identified a Cu(I) state for one complex and a mixed Cu(I)/Cu(II) state for the other.
Conclusions:
- Ligand modification significantly alters the electronic structure of copper complexes.
- Advanced multiconfigurational computational methods are essential for accurately describing systems with complex electronic behaviors.
- DFT is insufficient for rationalizing the electronic properties of these specific redox-active ligand systems.
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