Year: 2026
Type: preprint
Abstract: Californium (Cf3+) complexes with several Keggin-type polyoxometalate (POM) ligands have been synthesized and characterized, providing the first serial approach to Cf chemistry and a unique occasion to contrast its coordination properties with that of other felements. Contrary to trivalent lanthanides, americium and curium, californium yields a higher diversity of structures. Using microgram amounts of 249Cf, nine new structures containing Cf3+ have been obtained with the POM ligands [PW11O39]7-, [SiW11O39]8-, [GeW11O39]8-, and [BW11O39]9-, representing the largest series of Cf compounds ever isolated and significantly expanding experimental data on POM compounds with heavy actinides. Cf3+ crystallizes as the typical 8coordinate sandwich complexes with Keggin ions, [Cf(XW11O39)2]n-, but the long-range bond distances and twist angles of the Cf-POM complexes depart from any previous case reported. Comparative compounds obtained with the nearly isometric lanthanides also underline the uniqueness of the Cf3+ compounds beyond the ion size effects. The now extended family of [M(XW11O39)2]n- complexes also revealed previously unobserved topological isomers in such complexes, defined here as iota (ι) and omega (ω), with the Cf complexes’ isomerism often differing from the other f-elements. This first series of isotypic Cf compounds, CsyHz[Cf(XW11O39)2]·nH2O, (X = P5+, Si4+, Ge4+, or B3+), combined with structures previously obtained with Am3+, Cm3+, and lanthanides allows for the determination of bond valence sum (BVS) parameters for Cf3+ as well as the experimental determination of its 8-coordinate ionic radius: 1.066 ± 0.004 Å.
Source: ChemRxiv
Authors: Ian Colliard, Gauthier J. -P. Deblonde
Institution: Lawrence Livermore National Laboratory
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223297021