Monomeric and Trimeric Thorium Chlorides Isolated from Acidic Aqueous Solution

Abstract

Two thorium­(IV) compounds, [Th­(H2O)4Cl4]·2­(HPy·Cl) (1) and (HPy)3[Th3(H2O)2Cl10(OH)5]·4­(HPy·Cl) (2) (HPy = pyridinium), were isolated from acidic aqueous solution. The compounds were synthesized at room temperature and subsequently characterized using single crystal X-ray diffraction along with Raman and IR spectroscopies. Whereas compound 1 is built from discrete mononuclear Th­(H2O)4Cl4 units, compound 2 consists of a novel hydroxo-bridged trimeric [Th3(OH)5]7+ core. Such species are largely absent from discussions of Th solution and solid-state chemistry and their isolation may be attributed to outer coordination sphere interactions that help stabilize the structural units; extensive hydrogen bonding and π–π stacking interactions are present in 1 and 2. Density functional theory calculations were performed to predict the respective vibrational frequencies of the structural units, and their relative stability was predicted at the correlated molecular theory level. Small-angle X-ray scattering analysis of [Th3(OH)5]7+ in water indicates that the trimeric structural unit remains intact and that it is indeed an important species that necessitates consideration in geochemical models and for design of Th materials from water.

Bridging the Transuranics with Uranium(IV) Sulfate Aqueous Species and Solid Phases

“…In addition, a Th3 trimer has recently been isolated. (22) On the other hand, the higher acidity of Pu IV promotes the formation of larger molecular clusters, including Pu16,(23) Pu22,(23) and Pu38, (24) in addition to the ubiquitous hexamer as isolated clusters (10) and, more recently, within a MOF framework. (25) Different from thorium, the diplutonium(IV) dihydroxide bridged dimer is more elusive, isolated only once, with nitrate ligands, (26) and, more recently, singly bridged via an oxo ligand also with nitrate ligands.…”

Influence of pH on CeIV-[AsIIIW9O33]9− association for the formation of hexanuclear cerium(iv) oxo-hydroxo-clusters stabilized by trivacant polyanions

“…In order to estimate the stability of the four molecular systems in aqueous solution, we carried out SAXS (Small angle X-ray Scattering) analysis, which has been previously reported in literature for the characterization of molecular inorganic polyoxometalate-like species. [41][42][43][44] The strategy lies on the dissolution of a given amount of crystalline products of the different compounds 1-4 in water, poured in a 1.5 mm diameter glass capillary, with the targeted concentration of 25 mmol.L -1 . Unfortunately, in the case of compounds 1 and 2, and probably due to their relatively low charge (i. e. -2 and -5 for compound 1 and 2, respectively), we were not able to solubilize their crystals sufficiently to get an exploitable SAXS signal.…”

Tetranuclear oxido-bridged thorium(iv) clusters obtained using tridentate Schiff bases

“…Even at the time of submission of the present work, thorium chemistry continues to surprise the inorganic chemistry community. [85][86][87][88][89][90][91] For example, the number of the crystallographically characterised Th(III) complexes (mainly with cyclopentadienyl ancillary ligands) increases and the first example of a square planar thorium complex has been just reported. 89 Many scientists believe that with the harmful effects of global climate change becoming more evident with every passing year, more research activity and allocated resources will help the Z = 90 element realize its great potential and become a truly valuable source of materials in our energy economy.…”