The Curium Aqua Ion

Abstract

The coordination environment of the hydrated Cm3+ ion is probed both in the solid state and in solution. The analysis of single-crystal X-ray diffraction data from [Cm(H2O)9](CF3SO3)3 determines that the Cm species is surrounded by nine coordinating waters with a tricapped-trigonal-prismatic geometry involving six short Cm-O distances at 2.453(1) A and three longer Cm-O distances at 2.545(1) A. The Cm nona-aqua triflate is isostructural with the series of lanthanide and actinide [R(H2O)9](CF3SO3)3 (R=La-Lu, Pu) compounds. A similar nona-aqua geometry is seen for the coordination environment of Cm in aqueous solution, as probed by high-energy X-ray scattering and extended X-ray absorption fine structure spectroscopy, although the splitting in the first coordination shell is increased from 0.092(2) in the solid to 0.16(2) A in solution. This increase in splitting of the Cm-water distances in the first coordination sphere is discussed in terms of its potential relevance to the previously observed decrease in coordinating waters with decreasing ionic radius about the f-ion in solution.

Thorium nanochemistry: the solution structure of the Th(iv)–hydroxo pentamer

“…A peak at 3.12(8) Å is attributed to the corresponding H atoms from the Th-bound waters. 36 A correlation at 3.9 Å results from 1.1(2) Th-Th interactions, in excellent agreement with the XAFS data ( Table 2). Second coordination sphere waters give rise to a broad peak at about 4.5-5.5 Å, with possibly some chloride ion contribution.…”

From Yellow to Black: Dramatic Changes between Cerium(IV) and Plutonium(IV) Molybdates

“…[4][5][6][7][8][9][10][11][12][13][14] Exploration of this field is filled with opportunity as there are only a few systems that have systematically spanned the lanthanide and actinide series such as the aquo-triflates, phosphonates, and phosphites. [15][16][17][18][19][20][21][22][23][24][25] It is in this objective we have chosen to explore the rare earth molybdates.…”

Structure of the Homoleptic Thorium(IV) Aqua Ion [Th(H2O)10]Br4

“…[11] Thorium near-neighbor correlations are clearly visible from the pair-distribution function (PDF, Figure 2), which was obtained following a Fourier transform of scattering data after subtracting correlations not involving thorium. [12] There are three notable features in the PDF, the assignment of which are assisted by the structure of the solid-state sample. The first intense peak centered at 2.46(1) is attributed primarily to Th-O water correlations.…”