ORCID Profile
0000-0001-7984-1715
Current Organisation
Oak Ridge National Laboratory
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Publisher: Royal Society of Chemistry (RSC)
Date: 2006
DOI: 10.1039/B611046K
Abstract: A series of thorium(IV) perrhenato- and pertechnetato-complexes with P[double bond, length as m-dash]O donor ligands have been prepared and characterised both in the solid state and in solution. Isostructural complexes of general formula [Th(MO(4))(4)(L)(4)], where M = Re or Tc and L = triethylphosphate (TEP) (2 and 7), tri-iso-butylphosphate (TiBP) (3 and 8) and tri-n-butylphosphine oxide (TBPO) (4 and 9) have been prepared from the novel starting materials [Th(ReO(4))(4)] x 4H(2)O (1) and [Th(TcO(4))(4)] x 4H(2)O (6). The reaction of or with triphenylphosphine oxide (TPPO) in MeOH has also led to the synthesis of [Th(MO(4))(3)(TPPO)(3)(OCH(3))(HOCH(3))] (M = Re (5) or Tc (10)). While the structural characterisation of 4 and 9 has been previously described, we report for the first time the structural characterisation of 2 and 5, with a partial structural refinement of 3. Vibrational spectroscopic analysis confirms that the Tc complexes not characterised by single crystal X-ray diffraction are indeed isostructural with the perrhenate complexes with the same P[double bond, length as m-dash]O donor ligand. In all cases, monodentate coordination of the Group 7 tetraoxo anion is observed. (31)P NMR spectroscopy indicates that in all the phosphine oxide-based complexes there is one dominant solution species. For the phosphate based systems, the presence of pertechnetate appears to inhibit P[double bond, length as m-dash]O donor ligand complexation in solution, whereas a significant proportion of each phosphate remains coordinated to Th(IV) when perrhenate is present as the counter ligand. These results give some indication as to the mechanism of pertechnetate co-extraction with tetravalent cations in the presence of tri-n-butyl phosphate in the Plutonium and Uranium Recovery by Extraction (PUREX) process.
Publisher: Royal Society of Chemistry (RSC)
Date: 2004
DOI: 10.1039/B404424J
Abstract: The ability of [TcO(4)](-) to coordinate directly to tetra- and hexa-valent actinides in the presence of organic P[double bond, length as m-dash]O ligands is confirmed in the crystallographically characterised complexes [UO(2)(TcO(4))(2)(Ph(3)PO)(3)] and [Th(TcO(4))(4)((n)Bu(3)PO)(4)].
Publisher: American Chemical Society (ACS)
Date: 13-09-2005
DOI: 10.1021/IC0507971
Abstract: We report the synthesis, structural, and spectroscopic characterization of a series of uranium(IV)-perrhenato complexes. Three isostructural complexes with general formula [U(ReO4)4(L)4] (where L = tri-n-butylphosphine oxide/TBPO (2), triethyl phosphate/TEP (3), or tri-iso-butyl phosphate/TiBP (4)), have been synthesized, both through the photoreduction of ethanolic {UO2}2+ solutions and also via a novel U(IV) starting material, U(ReO4)4.5H2O (1). Compound 1 has also been used in the preparation of [U(ReO4)4(TPPO)3(CH3CN)].2CH3CN (5) and [U(ReO4)(DPPMO2)3(OH)][ReO4]2.2CH3CN (6), where TPPO represents triphenylphosphine oxide and DPPMO2 represents bis(diphenylphosphino)methane dioxide. All six complexes have been spectroscopically characterized using NMR, UV-vis-NIR, and IR techniques, with 2, 3, 5, and 6 also fully structurally characterized. The U atoms in compounds 2-6 all exhibit eight-coordinate geometry with up to four perrhenate groups in addition to three (DPPMO2 and TPPO) or four (TEP, TiBP, TBPO) coordinated organic ligands. In the case of compounds 5 and 6, the coordination of eight ligands to the U(IV) center is completed by the binding of a solvent molecule (CH3CN) and OH-, respectively. Solid-state physical analysis (elemental and thermogravimetric) and infrared spectroscopy are in agreement with the structural studies. The crystallographic data suggest that the strength of the U(IV)-O-donor ligand bonds decreases across the series R3PO > [ReO4]- > (RO)3PO. Solution-state IR and 31P NMR spectroscopy appear to be in agreement with these solid-state results.
Publisher: Elsevier BV
Date: 10-2007
Publisher: International Union of Crystallography (IUCr)
Date: 17-01-2006
DOI: 10.1107/S0108768105036931
Abstract: The crystal structures of the title complexes were measured at several temperatures between room temperature and 100 K. Each s le shows reversible crystal-to-crystal phase transitions as the temperature is varied. The behaviour of [U(ReO 4 ) 4 (TBPO) 4 ] (I) and [Th(ReO 4 ) 4 (TBPO) 4 ] (II) (TBPO = tri- n -butylphosphine oxide) is very similar at room temperature, crystals of (I) and (II) are isostructural, with space group I\\bar 42m, and reducing the temperature to 100 K causes a lowering of the space-group symmetry to C-centred cells, space groups Cc for (I) and Cmc 2 1 for (II). The variation of lattice symmetry of [Th(TcO 4 ) 4 (TBPO) 4 ] (III) was found to be somewhat different, with the body-centred cubic space group, I\\bar 43m, occurring at 293 K, a reduction of symmetry at 230 K to the C-centred orthorhombic space group, Cmc 2 1 , and a further transition to the primitive orthorhombic space group, Pbc 2 1 , below 215 K. Elucidation of the correct space-group symmetry and the subsequent refinement was complicated in some cases by the twinning by pseudo-merohedry that arises from the lowering of the space-group symmetry, occurring as the temperature is reduced. All three of the crystal structures determined at room temperature have high atomic displacement parameters, particularly of the n Bu groups, and (III) shows disorder of some of the O atoms. The structures in the space group Cmc 2 1 , show some disorder of n Bu groups, but are otherwise reasonably well ordered the structures of (I) in Cc and (III) in Pbc 2 1 are ordered, even to the ends of the alkyl chains. Inter-comparison of the structures measured below 293 K, using the program OFIT from the SHELXTL package, showed that generally, they are remarkably alike, with weighted r.m.s. deviations of the M , M ′ and P atoms of less than 0.1 Å, as are the 293 K structures of (I) and (II) with their low-temperature counterparts. However, the structure of (III) measured in the space group Cmc 2 1 is significantly different from both the structure of (III) at 293 K and that found below 215 K, with weighted r.m.s. deviations of the Th, Tc and P atoms of 0.40 and 0.37 Å, respectively. An extensive network of weak intra- and intermolecular C—H...O hydrogen bonds found between the atoms of the n Bu and [ M ′O 4 ] groups probably influences the packing and the overall geometry of the molecules.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United States of America
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Andrew Sutton.