Anion encapsulation drives the formation of dimeric GdIII[15-metallacrown-5]3+ complexes in aqueous solution

Metallacrown complexes capable of sequesteringdianions, as shown in the solid state, also exist inaqueous solution at neutral pH, as demonstrated bycalorimetric and mass spectrometric data. The driving forces for the formation of these dimeric complexes in solution strongly depend on the chain length of the guest rather than its degree of unsaturation.