title: Thorium nanochemistry: the solution structure of the Th(IV)-hydroxo pentamer.
abstract: Tetravalent thorium exhibits a strong tendency towards hydrolysis and subsequent polymerization. Polymeric species play a crucial role in understanding thorium solution chemistry, since their presence causes apparent solubility several orders of magnitude higher than predicted by thermodynamic data bases. Although electrospray mass spectrometry (ESI MS) identifies Th(IV) dimers and pentamers unequivocally as dominant species close to the solubility limit, the molecular structure of Th(5)(OH)(y) polymers was hitherto unknown. In the present study, X-ray absorption fine structure (XAFS) spectroscopy, high energy X-ray scattering (HEXS) measurements, and quantum chemical calculations are combined to solve the pentamer structure. The most favourable structure is represented by two Th(IV) dimers linked by a central Th(IV) cation through hydroxide bridges.
authors.affiliation: Institut für Nukleare Entsorgung, Karlsruhe Institute of Technology (KIT-INE), Karlsruhe, Germany.
authors.forename: Clemens
authors.initials: C
authors.lastname: Walther
authors.forename: Jörg
authors.initials: J
authors.lastname: Rothe
authors.forename: Bernd
authors.initials: B
authors.lastname: Schimmelpfennig
authors.forename: Markus
authors.initials: M
authors.lastname: Fuss