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Cobalt Complexes with Aminophenolate Ligands: Spin Crossover and Ligand Versatility.

I Haseena Ismail¹, Marcus J Giansiracusa¹, Robert W Gable¹

¹School of Chemistry, University of Melbourne, Parkville 3010, Victoria, Australia.

Inorganic Chemistry

|January 6, 2025

Summary

This study introduces novel cobalt complexes with switchable properties, demonstrating the first cobalt-iminosemiquinonate complex exhibiting spin crossover behavior for potential molecular materials.

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Published on: July 21, 2011

Area of Science:

Coordination Chemistry
Materials Science
Supramolecular Chemistry

Background:

Switchable molecules are crucial for developing advanced materials with tunable properties.
Cobalt complexes offer diverse electronic structures due to their redox activity.
Ligand design plays a key role in modulating metal complex behavior.

Purpose of the Study:

To synthesize and characterize a new family of heteroleptic cobalt complexes.
To investigate the spin crossover phenomenon in these cobalt complexes.
To explore the potential of these complexes in molecular materials and chemical reactivity.

Main Methods:

Synthesis of eight novel cobalt complexes featuring 2-aminophenol derivatives and tris(2-pyridylmethyl)amine (tpa) ligands.
Characterization using spectroscopic and crystallographic techniques.
Variable temperature electronic spectroscopy and Density Functional Theory (DFT) calculations to study spin crossover.

Main Results:

Isolation of high-spin Co(II) and low-spin Co(III) complexes with no solid-state thermal interconversion.
Observation of Co(II) spin crossover in solution for a specific complex (3b) via electronic spectroscopy.
DFT calculations corroborated experimental findings, supporting the observed electronic behaviors.

Conclusions:

This work reports the first cobalt-iminosemiquinonate complex exhibiting spin crossover.
The electronic structure versatility of these complexes, arising from redox-active cobalt and adaptable ligands, is highlighted.
These findings suggest significant promise for applications in molecular materials and catalysis.