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Jiang-gao Mao - One of the best experts on this subject based on the ideXlab platform.
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exploration of new birefringent crystals in bismuth d0 transition metal Selenites
Chemistry: A European Journal, 2019Co-Authors: Yaping Gong, Fang Kong, Jiang-gao MaoAbstract:The first examples of bismuth fluoride Selenites with d0 -TM/TeVI polyhedrons, namely, Bi4 TiO2 F4 (SeO3 )4 (1), Bi4 NbO3 F3 (SeO3 )4 (2), Bi4 TeO4 F2 (TeO3 )2 (SeO3 )2 (3), Bi2 F2 (MoO4 )(SeO3 ) (4) and Bi2 ZrO2 F2 (SeO3 )2 (5) have been successfully synthesized under hydrothermal reactions by aliovalent substitution. The five new compounds feature three different types of structures. Compounds 1-3, containing TiIV , NbV and TeVI respectively, are isostructural, exhibiting a new 3D framework composed of a 3D bismuth oxyfluoride architecture, with intersecting tunnels occupied by d0 -TM/TeVI octahedrons and selenite/tellurite groups. Interestingly, compound Bi4 TeO4 F2 (TeO3 )2 (SeO3 )2 (3) is the first structure containing SeIV and mixed-valent TeIV /TeVI cations simultaneously. Compound 4 features a new 3D structure formed by a 3D bismuth oxyfluoride network with MoO4 tetrahedrons and Selenites groups imbedded in the 1D tunnels. Compound 5 displays a novel pillar-layered 3D open framework, consisting of 2D bismuth oxide layers bridged by the [ZrO2 F2 (SeO3 )2 ]6- polyanions. Theoretical calculations revealed that the five compounds displayed very strong birefringence. The birefringence values of compounds 1-3, especially, are above 0.19 at 1064 nm, which are larger than the mineral calcite. Based on the structure and property analysis, it was found that the asymmetric SeO3 groups (and TeO3 in compound 3) displayed the largest anisotropy, compared with the bismuth cations and the d0 -TM/Te polyhedra, which is beneficial to the birefringence.
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three new d10 transition metal Selenites containing po4 tetrahedron cd7 hpo4 2 po4 2 seo3 2 cd6 po4 1 34 seo3 4 66 and zn3 hpo4 seo3 2 h2o
Journal of Solid State Chemistry, 2018Co-Authors: Jiang-gao Mao, Yaping Gong, Fang KongAbstract:Abstract Three new d10 transition metal Selenites containing PO4 tetrahedron, namely, Cd7(HPO4)2(PO4)2(SeO3)2 (1), Cd6(PO4)1.34(SeO3)4.66 (2) and Zn3(HPO4)(SeO3)2(H2O) (3), have been synthesized by hydrothermal reaction. They feature three different structural types. Compound 1 exhibits a novel 3D network composed of 3D cadmium selenite open framework with phosphate groups filled in the 1D helical tunnels. The structure of compound 2 displays a new 3D framework consisted of 2D cadmium oxide layers bridged by SeO3 and PO4 groups. Compound 3 is isostructural with the reported solids of Co3(SeO3)3-x(PO3OH)x(H2O) when x is equal to 1.0. Its structure could be viewed as a 3D zinc oxide open skeleton with SeO3 and HPO4 polyhedra attached on the wall of the tunnels. They represent the only examples in metal selenite phosphates in addition to the above cobalt compounds. Optical diffuse reflectance spectra revealed that these solids are insulators, which are consistent with the results of band structure computations based on DFT algorithm.
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a series of new silver Selenites with d0 tm cations
ChemInform, 2016Co-Authors: Qian Qian, Fang Kong, Jiang-gao MaoAbstract:Systematic explorations of new phases in the Ag+–Ti4+/Zr4+/Nb5+/Ta5+–Se4+–O(F) system by hydrothermal syntheses or standard high temperature solid-state reactions resulted in four new mixed-metal silver Selenites, namely, Ag3Ti3O3(SeO3)4F (1, P63), Ag2ZrF2(SeO3)2 (2, Cmca) and AgMO(SeO3)2 (M = Nb, 3; Ta, 4) in the space group Cmcm. Ag3Ti3O3(SeO3)4F features an interesting [Ti3O3(SeO3)4]2− 3D anionic framework composed of 1D chains of corner-sharing TiO6 octahedra which are further interconnected by tridentate bridging SeO32− anions, displaying 1D hexagonal channels of Ti6Se6 12-member rings (MRs) along the c-axis, filled by the Ag+ cations and isolated F− anions. More interestingly, it displays a moderate strong Second-Harmonic Generation (SHG) response about 2 times that of KH2PO4 (KDP). Compound 2 features a novel 1D [ZrF2(SeO3)2]2− anionic chain composed of edge-sharing ZrO4F4 polyhedra in which two neighboring Zr4+ cations are further bridged by a pair of selenite anions. Compounds 3 and 4 are isostructural and their structures feature 1D anionic chains of [MO(SeO3)2]− (M = Nb, Ta) which are separated by Ag+ cations, the 1D [MO(SeO3)2]− (M = Nb, Ta) chain is formed by 1D chains of corner-sharing MO6 (M = Nb, Ta) octahedra in which two neighboring metal centers are also bridged by a pair of selenite anions. Other characterizations including thermal analyses, optical and luminescence property measurements have also been performed.
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bifseo3 an excellent shg material designed by aliovalent substitution
Journal of the American Chemical Society, 2016Co-Authors: Mingli Liang, Fang Kong, Jiang-gao MaoAbstract:The first bismuth selenite fluoride, BiFSeO3, was obtained by aliovalent substitution of 2D BiOIO3. Its structure features a 3D network composed of 1D [BiF]2+ chains interconnected by SeO3 groups. BiFSeO3 exhibits a very strong second harmonic generation (SHG) effect of about 13.5 times that of KH2PO4 (KDP) under 1064 nm laser radiation and 1.1 times that of KTiOPO4 (KTP) under 2.05 μm laser radiation, which is the highest among all of the metal Selenites reported. It has also very simple chemical composition and can be synthesized easily under mild hydrothermal conditions.
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BiFSeO3: An Excellent SHG Material Designed by Aliovalent Substitution
2016Co-Authors: Mingli Liang, Fang Kong, Jiang-gao MaoAbstract:The first bismuth selenite fluoride, BiFSeO3, was obtained by aliovalent substitution of 2D BiOIO3. Its structure features a 3D network composed of 1D [BiF]2+ chains interconnected by SeO3 groups. BiFSeO3 exhibits a very strong second harmonic generation (SHG) effect of about 13.5 times that of KH2PO4 (KDP) under 1064 nm laser radiation and 1.1 times that of KTiOPO4 (KTP) under 2.05 μm laser radiation, which is the highest among all of the metal Selenites reported. It has also very simple chemical composition and can be synthesized easily under mild hydrothermal conditions
Fang Kong - One of the best experts on this subject based on the ideXlab platform.
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exploration of new birefringent crystals in bismuth d0 transition metal Selenites
Chemistry: A European Journal, 2019Co-Authors: Yaping Gong, Fang Kong, Jiang-gao MaoAbstract:The first examples of bismuth fluoride Selenites with d0 -TM/TeVI polyhedrons, namely, Bi4 TiO2 F4 (SeO3 )4 (1), Bi4 NbO3 F3 (SeO3 )4 (2), Bi4 TeO4 F2 (TeO3 )2 (SeO3 )2 (3), Bi2 F2 (MoO4 )(SeO3 ) (4) and Bi2 ZrO2 F2 (SeO3 )2 (5) have been successfully synthesized under hydrothermal reactions by aliovalent substitution. The five new compounds feature three different types of structures. Compounds 1-3, containing TiIV , NbV and TeVI respectively, are isostructural, exhibiting a new 3D framework composed of a 3D bismuth oxyfluoride architecture, with intersecting tunnels occupied by d0 -TM/TeVI octahedrons and selenite/tellurite groups. Interestingly, compound Bi4 TeO4 F2 (TeO3 )2 (SeO3 )2 (3) is the first structure containing SeIV and mixed-valent TeIV /TeVI cations simultaneously. Compound 4 features a new 3D structure formed by a 3D bismuth oxyfluoride network with MoO4 tetrahedrons and Selenites groups imbedded in the 1D tunnels. Compound 5 displays a novel pillar-layered 3D open framework, consisting of 2D bismuth oxide layers bridged by the [ZrO2 F2 (SeO3 )2 ]6- polyanions. Theoretical calculations revealed that the five compounds displayed very strong birefringence. The birefringence values of compounds 1-3, especially, are above 0.19 at 1064 nm, which are larger than the mineral calcite. Based on the structure and property analysis, it was found that the asymmetric SeO3 groups (and TeO3 in compound 3) displayed the largest anisotropy, compared with the bismuth cations and the d0 -TM/Te polyhedra, which is beneficial to the birefringence.
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three new d10 transition metal Selenites containing po4 tetrahedron cd7 hpo4 2 po4 2 seo3 2 cd6 po4 1 34 seo3 4 66 and zn3 hpo4 seo3 2 h2o
Journal of Solid State Chemistry, 2018Co-Authors: Jiang-gao Mao, Yaping Gong, Fang KongAbstract:Abstract Three new d10 transition metal Selenites containing PO4 tetrahedron, namely, Cd7(HPO4)2(PO4)2(SeO3)2 (1), Cd6(PO4)1.34(SeO3)4.66 (2) and Zn3(HPO4)(SeO3)2(H2O) (3), have been synthesized by hydrothermal reaction. They feature three different structural types. Compound 1 exhibits a novel 3D network composed of 3D cadmium selenite open framework with phosphate groups filled in the 1D helical tunnels. The structure of compound 2 displays a new 3D framework consisted of 2D cadmium oxide layers bridged by SeO3 and PO4 groups. Compound 3 is isostructural with the reported solids of Co3(SeO3)3-x(PO3OH)x(H2O) when x is equal to 1.0. Its structure could be viewed as a 3D zinc oxide open skeleton with SeO3 and HPO4 polyhedra attached on the wall of the tunnels. They represent the only examples in metal selenite phosphates in addition to the above cobalt compounds. Optical diffuse reflectance spectra revealed that these solids are insulators, which are consistent with the results of band structure computations based on DFT algorithm.
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a series of new silver Selenites with d0 tm cations
ChemInform, 2016Co-Authors: Qian Qian, Fang Kong, Jiang-gao MaoAbstract:Systematic explorations of new phases in the Ag+–Ti4+/Zr4+/Nb5+/Ta5+–Se4+–O(F) system by hydrothermal syntheses or standard high temperature solid-state reactions resulted in four new mixed-metal silver Selenites, namely, Ag3Ti3O3(SeO3)4F (1, P63), Ag2ZrF2(SeO3)2 (2, Cmca) and AgMO(SeO3)2 (M = Nb, 3; Ta, 4) in the space group Cmcm. Ag3Ti3O3(SeO3)4F features an interesting [Ti3O3(SeO3)4]2− 3D anionic framework composed of 1D chains of corner-sharing TiO6 octahedra which are further interconnected by tridentate bridging SeO32− anions, displaying 1D hexagonal channels of Ti6Se6 12-member rings (MRs) along the c-axis, filled by the Ag+ cations and isolated F− anions. More interestingly, it displays a moderate strong Second-Harmonic Generation (SHG) response about 2 times that of KH2PO4 (KDP). Compound 2 features a novel 1D [ZrF2(SeO3)2]2− anionic chain composed of edge-sharing ZrO4F4 polyhedra in which two neighboring Zr4+ cations are further bridged by a pair of selenite anions. Compounds 3 and 4 are isostructural and their structures feature 1D anionic chains of [MO(SeO3)2]− (M = Nb, Ta) which are separated by Ag+ cations, the 1D [MO(SeO3)2]− (M = Nb, Ta) chain is formed by 1D chains of corner-sharing MO6 (M = Nb, Ta) octahedra in which two neighboring metal centers are also bridged by a pair of selenite anions. Other characterizations including thermal analyses, optical and luminescence property measurements have also been performed.
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bifseo3 an excellent shg material designed by aliovalent substitution
Journal of the American Chemical Society, 2016Co-Authors: Mingli Liang, Fang Kong, Jiang-gao MaoAbstract:The first bismuth selenite fluoride, BiFSeO3, was obtained by aliovalent substitution of 2D BiOIO3. Its structure features a 3D network composed of 1D [BiF]2+ chains interconnected by SeO3 groups. BiFSeO3 exhibits a very strong second harmonic generation (SHG) effect of about 13.5 times that of KH2PO4 (KDP) under 1064 nm laser radiation and 1.1 times that of KTiOPO4 (KTP) under 2.05 μm laser radiation, which is the highest among all of the metal Selenites reported. It has also very simple chemical composition and can be synthesized easily under mild hydrothermal conditions.
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BiFSeO3: An Excellent SHG Material Designed by Aliovalent Substitution
2016Co-Authors: Mingli Liang, Fang Kong, Jiang-gao MaoAbstract:The first bismuth selenite fluoride, BiFSeO3, was obtained by aliovalent substitution of 2D BiOIO3. Its structure features a 3D network composed of 1D [BiF]2+ chains interconnected by SeO3 groups. BiFSeO3 exhibits a very strong second harmonic generation (SHG) effect of about 13.5 times that of KH2PO4 (KDP) under 1064 nm laser radiation and 1.1 times that of KTiOPO4 (KTP) under 2.05 μm laser radiation, which is the highest among all of the metal Selenites reported. It has also very simple chemical composition and can be synthesized easily under mild hydrothermal conditions
Thomas E Albrechtschmitt - One of the best experts on this subject based on the ideXlab platform.
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variable dimensionality and new uranium oxide topologies in the alkaline earth metal uranyl Selenites ae uo2 seo3 2 ae ca ba and sr uo2 seo3 2 2h2o
Journal of Solid State Chemistry, 2002Co-Authors: Philip M Almond, Shane Peper, Eric Bakker, Thomas E AlbrechtschmittAbstract:Abstract Three new alkaline-earth metal uranyl Selenites, Ca[(UO 2 )(SeO 3 ) 2 ] (1), Sr[(UO 2 )(SeO 3 ) 2 ] · 2H 2 O (2), and Ba[(UO 2 )(SeO 3 ) 2 ] (3), have been prepared from the reactions of CaCO 3 and Ca(OH) 2 , SrCl 2 and Sr(OH) 2 , or BaCl 2 and Ba(OH) 2 with UO 3 and SeO 2 under mild hydrothermal conditions. Single-crystal X-ray diffraction experiments reveal that the structures of 1–3 differ in both connectivity and dimensionality even though all contain the same fundamental building unit, namely [UO 2 (SeO 3 ) 4 ]. This polyhedron consists of a linear uranyl unit that is bound by one chelating and three bridging selenite anions creating a pentagonal bipyramidal environment around the U(VI) center. The crystal structure of 1 contains one-dimensional ribbons where the edges are terminated by monodentate selenite anions. The interior of the ribbons are constructed from edge-sharing pentagonal bipyramidal UO 7 units. The structure of 2 is also one-dimensional; however, here there are chains of edge-sharing pentagonal bipyramidal UO 7 dimers that are connected by bridging selenite anions. Ba[(UO 2 )(SeO 3 ) 2 ] (3) is two-dimensional, and the highly ruffled anionic sheets present in this structure are formed from both bridging and chelating/bridging selenite anions bound to uranyl moieties. The anionic substructures in 1–3 are separated by Ca 2+ , Sr 2+ , or Ba 2+ cations. Crystallographic data (193 K, Mo Kα , λ =0.71073): 1, triclinic, space group P 1 , a =5.5502(6) A, b =6.6415(7) A, c =11.013(1) A, α =104.055(2)°, β =93.342(2)°, γ =110.589(2)°, Z =2, R ( F )=4.56% for 100 parameters with 1530 reflections with I >2 σ ( I ); 2, triclinic, space group P 1 , a =7.0545(5) A, b =7.4656(5) A, c =10.0484(6) A, α =106.995(1)°, β =108.028(1)°, γ=98.875(1)°, Z =2, R ( F )= 2.43% for 128 parameters with 2187 reflections with I >2 σ ( I ); 3, monoclinic, space group P2 1 /c , a =7.3067(6) A, b =8.1239(7) A, c =13.651(1) A, β =100.375(2)°, Z =4, R ( F )=4.31% for 105 parameters with 1824 reflections with I> 2 σ ( I ).
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hydrothermal syntheses structures and properties of the new uranyl Selenites ag 2 uo 2 seo 3 2 m uo 2 hseo 3 seo 3 m k rb cs tl and pb uo 2 seo 3 2
Inorganic Chemistry, 2002Co-Authors: Philip M Almond, Thomas E AlbrechtschmittAbstract:The transition metal, alkali metal, and main group uranyl Selenites, Ag(2)(UO(2))(SeO(3))(2) (1), K[(UO(2))(HSeO(3))(SeO(3))] (2), Rb[(UO(2))(HSeO(3))(SeO(3))] (3), Cs[(UO(2))(HSeO(3))(SeO(3))] (4), Tl[(UO(2))(HSeO(3))(SeO(3))] (5), and Pb(UO(2))(SeO(3))(2) (6), have been prepared from the hydrothermal reactions of AgNO(3), KCl, RbCl, CsCl, TlCl, or Pb(NO(3))(2) with UO(3) and SeO(2) at 180 degrees C for 3 d. The structures of 1-5 contain similar [(UO(2))(SeO(3))(2)](2-) sheets constructed from pentagonal bipyramidal UO(7) units that are joined by bridging SeO(3)(2-) anions. In 1, the selenite oxo ligands that are not utilized within the layers coordinate the Ag(+) cations to create a three-dimensional network structure. In 2-5, half of the selenite ligands are monoprotonated to yield a layer composition of [(UO(2))(HSeO(3))(SeO(3))](1-), and coordination of the K(+), Rb(+), Cs(+), and Tl(+) cations occurs through long ionic contacts. The structure of 6 contains a uranyl selenite layered substructure that differs substantially from those in 1-5 because the selenite anions adopt both bridging and chelating binding modes to the uranyl centers. Furthermore, the Pb(2+) cations form strong covalent bonds with these anions creating a three-dimensional framework. These cations occur as distorted square pyramidal PbO(5) units with stereochemically active lone pairs of electrons. These polyhedra align along the c-axis to create a polar structure. Second-harmonic generation (SHG) measurements revealed a response of 5x alpha-quartz for 6. The diffuse reflectance spectrum of 6 shows optical transitions at 330 and 440 nm. The trailing off of the 440 nm transition to longer wavelengths is responsible for the orange coloration of 6.
Dong Woo Lee - One of the best experts on this subject based on the ideXlab platform.
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variable framework structures and centricities in alkali metal yttrium Selenites ay seo3 2 a na k rb and cs
Inorganic Chemistry, 2014Co-Authors: Seongeun Bang, Dong Woo LeeAbstract:Pure samples of a series of yttrium Selenites, AY(SeO3)2 (A = Na, K, Rb, and Cs), were prepared through hydrothermal reactions using A2CO3, Y(NO3)3·6H2O, and SeO2. All four materials have 3D framework structures; however, they exhibit different channel geometries. The three-dimensional framework of NaY(SeO3)2 consists of zigzag chains of vertex-shared YO7 polyhedra and SeO3 linkers. KY(SeO3)2 and RbY(SeO3)2 reveal channels composed of corner-shared YO6 octahedra and SeO3 polyhedra. CsY(SeO3)2 exhibits a highly symmetric cage structure with radially spreading linkages of YO6 and SeO3 groups. Close structural examinations suggest that the cation size and coordination environment significantly influence the backbone architectures and their centricities. Second-harmonic generation (SHG) measurements on the powder sample of NaY(SeO3)2 reveal that the NCS selenite possesses a similar SHG efficiency to that of NH4H2PO4 (ADP).
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Variable Framework Structures and Centricities in Alkali Metal Yttrium Selenites, AY(SeO3)2 (A = Na, K, Rb, and Cs)
2014Co-Authors: Seongeun Bang, Dong Woo LeeAbstract:Pure samples of a series of yttrium Selenites, AY(SeO3)2 (A = Na, K, Rb, and Cs), were prepared through hydrothermal reactions using A2CO3, Y(NO3)3·6H2O, and SeO2. All four materials have 3D framework structures; however, they exhibit different channel geometries. The three-dimensional framework of NaY(SeO3)2 consists of zigzag chains of vertex-shared YO7 polyhedra and SeO3 linkers. KY(SeO3)2 and RbY(SeO3)2 reveal channels composed of corner-shared YO6 octahedra and SeO3 polyhedra. CsY(SeO3)2 exhibits a highly symmetric cage structure with radially spreading linkages of YO6 and SeO3 groups. Close structural examinations suggest that the cation size and coordination environment significantly influence the backbone architectures and their centricities. Second-harmonic generation (SHG) measurements on the powder sample of NaY(SeO3)2 reveal that the NCS selenite possesses a similar SHG efficiency to that of NH4H2PO4 (ADP)
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from an open framework to a layered and a hexagonal tungsten oxide structure controlled transformation reactions of an extended solid state material cs3ga7 seo3 12 to ga oh seo3 and kga3 seo4 2 oh 6
Inorganic Chemistry, 2013Co-Authors: Hyun Sun Ahn, Dong Woo LeeAbstract:A highly symmetric open-framework gallium selenite, Cs3Ga7(SeO3)12, containing cubic superlattices has been synthesized by a standard solid-state reaction using Cs2CO3, Ga2O3, and SeO2 as reagents. Cs3Ga7(SeO3)12 exhibits a three-dimensional open-framework structure consisting of GaO4 tetrahedra, GaO6 octahedra, and SeO3 polyhedra. Step-by-step reactions of the solid-state material in aqueous KNO3 solution at different temperatures produce Ga(OH)(SeO3) with a layered structure and KGa3(SeO4)2(OH)6 having a hexagonal tungsten oxide (HTO) topology. Novel HTO layers capped by Se(6+) cations in KGa3(SeO4)2(OH)6 led us to synthesize other alkali metal gallium selenates, NaGa3(SeO4)2(OH)6 and RbGa3(SeO4)2(OH)6, using hydrothermal reactions. Thermal analyses, infrared spectroscopy, elemental analyses, and dipole moment calculations for the reported materials are also presented.
Philip M Almond - One of the best experts on this subject based on the ideXlab platform.
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variable dimensionality and new uranium oxide topologies in the alkaline earth metal uranyl Selenites ae uo2 seo3 2 ae ca ba and sr uo2 seo3 2 2h2o
Journal of Solid State Chemistry, 2002Co-Authors: Philip M Almond, Shane Peper, Eric Bakker, Thomas E AlbrechtschmittAbstract:Abstract Three new alkaline-earth metal uranyl Selenites, Ca[(UO 2 )(SeO 3 ) 2 ] (1), Sr[(UO 2 )(SeO 3 ) 2 ] · 2H 2 O (2), and Ba[(UO 2 )(SeO 3 ) 2 ] (3), have been prepared from the reactions of CaCO 3 and Ca(OH) 2 , SrCl 2 and Sr(OH) 2 , or BaCl 2 and Ba(OH) 2 with UO 3 and SeO 2 under mild hydrothermal conditions. Single-crystal X-ray diffraction experiments reveal that the structures of 1–3 differ in both connectivity and dimensionality even though all contain the same fundamental building unit, namely [UO 2 (SeO 3 ) 4 ]. This polyhedron consists of a linear uranyl unit that is bound by one chelating and three bridging selenite anions creating a pentagonal bipyramidal environment around the U(VI) center. The crystal structure of 1 contains one-dimensional ribbons where the edges are terminated by monodentate selenite anions. The interior of the ribbons are constructed from edge-sharing pentagonal bipyramidal UO 7 units. The structure of 2 is also one-dimensional; however, here there are chains of edge-sharing pentagonal bipyramidal UO 7 dimers that are connected by bridging selenite anions. Ba[(UO 2 )(SeO 3 ) 2 ] (3) is two-dimensional, and the highly ruffled anionic sheets present in this structure are formed from both bridging and chelating/bridging selenite anions bound to uranyl moieties. The anionic substructures in 1–3 are separated by Ca 2+ , Sr 2+ , or Ba 2+ cations. Crystallographic data (193 K, Mo Kα , λ =0.71073): 1, triclinic, space group P 1 , a =5.5502(6) A, b =6.6415(7) A, c =11.013(1) A, α =104.055(2)°, β =93.342(2)°, γ =110.589(2)°, Z =2, R ( F )=4.56% for 100 parameters with 1530 reflections with I >2 σ ( I ); 2, triclinic, space group P 1 , a =7.0545(5) A, b =7.4656(5) A, c =10.0484(6) A, α =106.995(1)°, β =108.028(1)°, γ=98.875(1)°, Z =2, R ( F )= 2.43% for 128 parameters with 2187 reflections with I >2 σ ( I ); 3, monoclinic, space group P2 1 /c , a =7.3067(6) A, b =8.1239(7) A, c =13.651(1) A, β =100.375(2)°, Z =4, R ( F )=4.31% for 105 parameters with 1824 reflections with I> 2 σ ( I ).
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hydrothermal syntheses structures and properties of the new uranyl Selenites ag 2 uo 2 seo 3 2 m uo 2 hseo 3 seo 3 m k rb cs tl and pb uo 2 seo 3 2
Inorganic Chemistry, 2002Co-Authors: Philip M Almond, Thomas E AlbrechtschmittAbstract:The transition metal, alkali metal, and main group uranyl Selenites, Ag(2)(UO(2))(SeO(3))(2) (1), K[(UO(2))(HSeO(3))(SeO(3))] (2), Rb[(UO(2))(HSeO(3))(SeO(3))] (3), Cs[(UO(2))(HSeO(3))(SeO(3))] (4), Tl[(UO(2))(HSeO(3))(SeO(3))] (5), and Pb(UO(2))(SeO(3))(2) (6), have been prepared from the hydrothermal reactions of AgNO(3), KCl, RbCl, CsCl, TlCl, or Pb(NO(3))(2) with UO(3) and SeO(2) at 180 degrees C for 3 d. The structures of 1-5 contain similar [(UO(2))(SeO(3))(2)](2-) sheets constructed from pentagonal bipyramidal UO(7) units that are joined by bridging SeO(3)(2-) anions. In 1, the selenite oxo ligands that are not utilized within the layers coordinate the Ag(+) cations to create a three-dimensional network structure. In 2-5, half of the selenite ligands are monoprotonated to yield a layer composition of [(UO(2))(HSeO(3))(SeO(3))](1-), and coordination of the K(+), Rb(+), Cs(+), and Tl(+) cations occurs through long ionic contacts. The structure of 6 contains a uranyl selenite layered substructure that differs substantially from those in 1-5 because the selenite anions adopt both bridging and chelating binding modes to the uranyl centers. Furthermore, the Pb(2+) cations form strong covalent bonds with these anions creating a three-dimensional framework. These cations occur as distorted square pyramidal PbO(5) units with stereochemically active lone pairs of electrons. These polyhedra align along the c-axis to create a polar structure. Second-harmonic generation (SHG) measurements revealed a response of 5x alpha-quartz for 6. The diffuse reflectance spectrum of 6 shows optical transitions at 330 and 440 nm. The trailing off of the 440 nm transition to longer wavelengths is responsible for the orange coloration of 6.