“…One of these is a four-membered ring of vertex-sharing pentagonal bipyramids, with a (WO 4 OH) 3– square pyramid located at the center of each ring, where it shares edges with each of the four uranyl bipyramids (Figure b). This unit is very similar to those found in dedecaniobate Keggin ions, as well as in uranyl chromates. , The other structural unit consists of two uranyl hexagonal bipyramids that are bridged by a peroxo ligand that is bidentate to each uranyl ion. Each of these hexagonal bipyramids is also coordinated by two bidentate (H 2 PO 4 ) 1– tetrahedra (Figure c).…”
Section: Resultssupporting
confidence: 66%
“…This unit is very similar to those found in dedecaniobate Keggin ions, 41 as well as in uranyl chromates. 42,43 The other structural unit consists of two uranyl hexagonal bipyramids that are bridged by a peroxo ligand that is bidentate to each uranyl ion. Each of these hexagonal bipyramids is also coordinated by two bidentate (H 2 PO 4 ) 1− tetrahedra (Figure 6c).…”
Transition-metal based polyoxometalate clusters have been known for decades, whereas those built from uranyl peroxide polyhedra have more recently emerged as a family of complex clusters. Here we report the synthesis and structures of six nanoscale uranyl peroxide cage clusters that contain either tungstate or molybdate polyhedra as part of the cage, as well as phosphate tetrahedra. These transition-metal-uranium hybrid clusters exhibit unique polyhedral connectivities and topologies that include 6-, 7-, 8-, 10-, and 12-membered rings of uranyl polyhedra and uranyl ions coordinated by bidentate peroxide in both trans and cis configurations. The transition-metal polyhedra appear to stabilize unusual units built of uranyl polyhedra, rather than templating their formation.
“…One of these is a four-membered ring of vertex-sharing pentagonal bipyramids, with a (WO 4 OH) 3– square pyramid located at the center of each ring, where it shares edges with each of the four uranyl bipyramids (Figure b). This unit is very similar to those found in dedecaniobate Keggin ions, as well as in uranyl chromates. , The other structural unit consists of two uranyl hexagonal bipyramids that are bridged by a peroxo ligand that is bidentate to each uranyl ion. Each of these hexagonal bipyramids is also coordinated by two bidentate (H 2 PO 4 ) 1– tetrahedra (Figure c).…”
Section: Resultssupporting
confidence: 66%
“…This unit is very similar to those found in dedecaniobate Keggin ions, 41 as well as in uranyl chromates. 42,43 The other structural unit consists of two uranyl hexagonal bipyramids that are bridged by a peroxo ligand that is bidentate to each uranyl ion. Each of these hexagonal bipyramids is also coordinated by two bidentate (H 2 PO 4 ) 1− tetrahedra (Figure 6c).…”
Transition-metal based polyoxometalate clusters have been known for decades, whereas those built from uranyl peroxide polyhedra have more recently emerged as a family of complex clusters. Here we report the synthesis and structures of six nanoscale uranyl peroxide cage clusters that contain either tungstate or molybdate polyhedra as part of the cage, as well as phosphate tetrahedra. These transition-metal-uranium hybrid clusters exhibit unique polyhedral connectivities and topologies that include 6-, 7-, 8-, 10-, and 12-membered rings of uranyl polyhedra and uranyl ions coordinated by bidentate peroxide in both trans and cis configurations. The transition-metal polyhedra appear to stabilize unusual units built of uranyl polyhedra, rather than templating their formation.
“…The NH 4 + cations are located between the sheets, together with the H 2 O group. The corrugated sheets are stacked perpendicular to c. These heteropolyhedral sheets are similar to those in the structures of synthetic uranyl chromates (Unruh et al, 2012) and molybdates (Obbade et al, 2003). (5) OW3-O8 3.013(7) <N1-O> 3.096 * Note that there are no obvious hydrogen bonds through H3a and there are two apparent hydrogen bonds through H3b.…”
Section: Description and Discussion Of The Structurementioning
confidence: 54%
“…The corrugated sheets are stacked perpendicular to c . These heteropolyhedral sheets are similar to those in the structures of synthetic uranyl chromates (Unruh et al ., 2012) and molybdates (Obbade et al , 2003). Fig.…”
Section: Description and Discussion Of The Structurementioning
The new mineral ammoniomathesiusite (IMA 2017-077), (NH 4 ) 5 (UO 2 ) 4 (SO 4 ) 4 (VO 5 )·4H 2 O, was found in the Burro mine, San Miguel County, Utah, USA, where it occurs as a secondary phase on asphaltum/quartz matrix in association with ammoniozippeite (2017-073), gypsum, jarosite and natrozippeite. The mineral forms pale yellow to greenish-yellow prisms, up to about 0.3 mm long, with pale yellow streak and bright yellow-green fluorescence. Crystals are transparent and have vitreous luster. The mineral is brittle, with Mohs hardness of 2½, stepped fracture and two cleavages: excellent on {110} and good on {001}. The calculated density is 3.672 g/cm 3 . Ammoniomathesiusite is optically uniaxial (-) with ω = 1.653(2) and ε = 1.609(2) (white light). Pleochroism is O green yellow, E colourless; O > E. Electron microprobe analyses yielded the empirical formula [(NH 4 ) 4.75 (U 1.00 O 2 ) 4 (S 1.00 O 4 ) 4 (V 1.00 O 5 )·4(H 2.07 O). The five strongest X-ray powder diffraction lines are [d obs Å(I)(hkl. Ammoniomathesiusite is tetragonal, P4/n, a = 14.9405(9), c = 7.1020(5) Å, V = 1585.3(2) Å 3 and Z = 2. The structure of ammoniomathesiusite (R 1 = 0.0218 for 3427 I > 2I) contains heteropolyhedral sheets based on [(UO 2 ) 4 (SO 4 ) 4 (VO 5 )] 5clusters. The structure is identical to that of mathesiusite, with NH 4 + in place of K + .
“…Uranyl molybdates tend to form framework structures [5] due to the flexibility and broad variation of U-O-Mo bond angles. Uranyl chromates constitute a particularly versatile class among the compounds considered as they exhibit all the features listed above: both mono- [6][7][8][9][10][11][12][13][14][15][16] and bidentate [17][18][19] linkage modes of CrO 4 tetrahedra to UO 7 uranyl bipyramids, formation of corner-sharing tetrahedral chromate polyanions [19][20][21], flexibility and variation of U-O-Cr angles similar to those in uranyl molybdates and formation of framework structures [22], and variability of coordination environments [23][24][25]. The tendency of the CrO 4 2− to form isopolyanions in acidic media leads to formation of structures involving simultaneously several polychromate moieties such as Cr 2 O 7 2− dimers, Cr 3 O 10 2− trimers and Cr 4 O 13 2− tetramers [26].…”
Three new uranyl dichromate compounds templated by aza-crown templates were obtained at room temperature by evaporation from aqueous solutions: 4 (3). The use of aza-crown templates made it possible to isolate unprecedented and complex one-dimensional units in 2 and 3, whereas the structure of 1 is based on simple uranyl-dichromate chains. It is very likely that the presence of relatively large organic molecules of aza-crown ethers does not allow uranyl chromate chain complexes to condense into the units of higher dimensionality (layers or frameworks). In general, the formation of 1, 2, and 3 is in agreement with the general principles elaborated for organically templated uranyl compounds. The negative charge of the [(UO 2 )(Cr 2 O 7 ) 2 (H 2 O)] 2− , [(UO 2 ) 2 (CrO 4 ) 2 (Cr 2 O 7 ) 2 (H 2 O)] 4− and [(UO 2 ) 3 (CrO 4 ) 4 (Cr 2 O 7 ) 2 ] 6− one-dimensional inorganic motifs is compensated by the protonation of all nitrogen atoms in the molecules of aza-crowns.
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