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Putting the squeeze on valence tautomerism in cobalt-dioxolene complexes
Aston Summers1, F Zahra M Zahir2, Gemma F Turner1
1School of Molecular Sciences, University of Western Australia, Crowley, Western Australia, Australia.
Nature Communications
|October 16, 2024
Summary
This study reveals how cobalt complexes switch electronic states (valence tautomerism) under temperature and pressure. Atomic-resolution X-ray diffraction clarifies structural changes, crucial for designing molecular switches.
Area of Science:
- Coordination Chemistry
- Materials Science
- Crystallography
Background:
- Molecules switching electronic states are key for applications like data storage.
- Valence tautomerism in metal complexes causes magnetic, color, and structural changes.
- Precise solid-state structural changes during valence tautomerism lack atomic resolution.
Purpose of the Study:
- To atomically characterize valence tautomerism in cobalt complexes using variable temperature and pressure.
- To elucidate the structural mechanisms of switching in response to external stimuli.
Main Methods:
- Single crystal X-ray diffraction under variable temperature and high pressure.
- Characterization of two isostructural cobalt complexes with differing steric hindrance.
Main Results:
- The less hindered complex shows two-step thermal valence tautomerism (high-spin Co(II)-seminquinonate to low-spin Co(III)-catecholate).
- The more hindered complex does not exhibit thermal valence tautomerism due to steric effects.
- Pressure induces valence tautomerism in both complexes, even in the thermally inactive one, with distinct pressure ranges.
Conclusions:
- Atomic-resolution structural data clarifies valence tautomerism mechanisms.
- Steric hindrance significantly impacts thermal and pressure-induced switching behavior.
- In situ high-pressure X-ray diffraction is vital for understanding structure-property relationships in molecular switches.
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