High-pressure studies of three polymorphs of a palladium(II) oxathioether macrocyclic complex

What is it about?

There are three known solid-state phases of the dichloro coordination complex formed between palladium(II) and the macrocyclic ligand 1-oxa-4,7-dithiacyclononane. We have studied the responses of all these phases to pressures exceeding 9 GPa (90,000 atmospheres) using single-crystal X-ray diffraction and other techniques. Two of the phases respond smoothly to compression, but the third one undergoes a reversible transition to a fourth phase. This transition involves changes to the conformation of the macrocycle and leads to an extensively disordered structure.

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Why is it important?

By combining the results of the X-ray diffraction experiments with those from other calculations, we were able to work out the mechanism of the phase transition and follow the changes to the structures by monitoring variations in geometric and bonding parameters.