The Structures and Optical Spectra of Hydrated Transplutonium Ions in the Solid State and in Solution

Stable nine-coordination: X-ray diffraction reveals highly symmetrical [M(H2O)9]3+ entities for the actinides americium and curium in single crystals of their triflate salts (see picture, yellow M, red O). Comparison of absorption spectra in solution confirm that these transplutonium ions are large enough to remain ninefold coordinated also in aqueous solution.