Terbium trapped in a molecular cage reaches rare +4 state

Chemists at the University of Iowa encased terbium in molecular cages built from a tungsten polyoxometalate with ligands and removed one electron using potassium persulfate, stabilizing the metal in the unusual +4 oxidation state. The process works under ambient conditions without special temperature, humidity or pressure controls.

• Terbium moved from its stable +3 state to rare +4 by removing one electron
• The cage combines a tungsten polyoxometalate with binding ligands
• Oxidation used potassium persulfate under ordinary ambient conditions
• The method could ease rare-earth separation and aid quantum technologies