Californium is difficult to prepare in its divalent state. Now, crystals of a Cf(II) crown–ether complex have been synthesized by reduction of a Cf(III) precursor with an Al/Hg amalgam. They exhibit 5f→6d transitions in the visible region and near-infrared emission that are highly sensitive to changes in the coordination environment.
- Todd N. Poe
- Harry Ramanantoanina
- Cristian Celis-Barros