Expanding the Remarkable Structural Diversity of Uranyl Tellurites:  Hydrothermal Preparation and Structures of K[UO₂Te₂O₅(OH)], Tl₃{(UO₂)₂[Te₂O₅(OH)](Te₂O₆)}·2H₂O, β-Tl₂[UO₂(TeO₃)₂], and Sr₃[UO₂(TeO₃)₂](TeO₃)₂

Abstract

The reactions of UO(2)(C(2)H(3)O(2))(2).2H(2)O with K(2)TeO(3).H(2)O, Na(2)TeO(3) and TlCl, or Na(2)TeO(3) and Sr(OH)(2).8H(2)O under mild hydrothermal conditions yield K[UO(2)Te(2)O(5)(OH)] (1), Tl(3)[(UO(2))(2)[Te(2)O(5)(OH)](Te(2)O(6))].2H(2)O (2) and beta-Tl(2)[UO(2)(TeO(3))(2)] (3), or Sr(3)[UO(2)(TeO(3))(2)](TeO(3))(2) (4), respectively. The structure of 1 consists of tetragonal bipyramidal U(VI) centers that are bound by terminal oxo groups and tellurite anions. These UO(6) units span between one-dimensional chains of corner-sharing, square pyramidal TeO(4) polyhedra to create two-dimensional layers. Alternating corner-shared oxygen atoms in the tellurium oxide chains are protonated to create short/long bonding patterns. The one-dimensional chains of corner-sharing TeO(4) units found in 1 are also present in 2. However, in 2 there are two distinct chains present, one where alternating corner-shared oxygen atoms are protonated, and one where the chains are unprotonated. The uranyl moieties in 2 are bound by five oxygen atoms from the tellurite chains to create seven-coordinate pentagonal bipyramidal U(VI). The structures of 3 and 4 both contain one-dimensional [UO(2)(TeO(3))(2)](2-) chains constructed from tetragonal bipyramidal U(VI) centers that are bridged by tellurite anions. The chains differ between 3 and 4 in that all of the pyramidal tellurite anions in 3 have the same orientation, whereas the tellurite anions in 4 have opposite orientations on each side of the chain. In 4, there are also additional isolated TeO(3)(2-) anions present. Crystallographic data: 1, orthorhombic, space group Cmcm, a = 7.9993(5) A, b = 8.7416(6) A, c = 11.4413(8) A, Z = 4; 2, orthorhombic, space group Pbam, a = 10.0623(8) A, b = 23.024(2) A, c = 7.9389(6) A, Z = 4; 3, monoclinic, space group P2(1)/n, a = 5.4766(4) A, b = 8.2348(6) A, c = 20.849(3) A, beta = 92.329(1) degrees, Z = 4; 4, monoclinic, space group C2/c, a = 20.546(1) A, b = 5.6571(3) A, c = 13.0979(8) A, beta = 94.416(1) degrees, Z = 4.

Hydrothermal syntheses and structures of the uranyl tellurates AgUO2(HTeO5) and Pb2UO2(TeO6)

“…Four of these, sheet, the pentagonal bipyramids are linked into four-membered rings, with a WO 5 square pyramid located at the center of the ring. These units are further linked into a sheet through the dimers of edge-sharing WO 6 The sheet of uranyl square bipyramids and TeO 6 octahedra in 2 is based on the autunite anion topology that consists only of squares. The connectivity of this net is 4.4.4.4 [32].…”

“…These rare minerals are from the oxidizied zone of a U deposit at Shinkolobwe, Democratic Republic of Congo, and the oxidized zone of a hydrothermal Au/Te deposit at the Moctezuma mine in Mexico [4]. More recently, 11 hydrothermally synthesized uranyl tellurites have been synthesized and structurally characterized: Pb 2 UO 2 (TeO 3 ) 3 [5] [6], Na 8 [(UO 2 ) 6 (TeO 3 ) 10 ] [7], A 2 [(UO 2 ) 3 (TeO 3 ) 2 O 2 ] (A¼K, Rb, Cs) [8], and K 4 [(UO 2 ) 5 (TeO 3 ) 2 O 5 ] [9]. Considerable structural diversity is exhibited by these compounds, which contain structural units consisting of uranyl tellurite chains, sheets, and frameworks.…”

“…Tellurate thus presents more binding sites than tellurite, and could potentially give more complex extended structures. The coordination of tellurate to metal centers is unusually strong, which enables it to stabilize high oxidation states of the transition metals in an aqueous solution that can then be crystallized, such as Ru(VI) in Na 6 (0.5 mmol) and 2 ml distilled water under hydrothermal conditions, respectively. Reactants were heated in 23 ml Teflon-lined Parr reaction vessels at 220 1C for nine days.…”

Tellurites of Hexavalent Uranium: First Observation of Polymerized (UO4)2– Tetraoxido Cores

“…Within the last decade, a number of uranyl tellurites with various monovalent and divalent cations have been obtained by hydrothermal methods and reported in the literature: K[(UO 2 )Te 2 O 5 (OH)], Tl 3 [(UO 2 ) 2 (Te 2 O 5 OH)(Te 2 O 6 )] · 2H 2 O, Sr 3 [UO 2 (TeO 3 ) 2 ](TeO 3 ) 2 , β‐Tl 2 [UO 2 (TeO 3 ) 2 ], α‐Tl 2 [UO 2 (TeO 3 ) 2 ], Na 8 [(UO 2 ) 6 (TeO 3 ) 10 ] . Solid‐state methods have also been applied for the synthesis of several compounds: A 2 [(UO 2 ) 3 (TeO 3 ) 2 O 2 ] (A = K, Rb, Cs) was obtained in sealed silica tubes and K 4 [(UO 2 ) 5 (TeO 3 ) 2 O 5 ] was obtained in air in alumina crucibles.…”

One-dimensional lanthanide selenite-carboxylate compounds: Synthesis, crystal structure and properties

“…Such materials can be designed and synthesized from a variety of compositional and structural combinations of individual inorganic and organic components [7][8][9][10]. Selenite as inorganic component of hybrids is of much interest because the stereochemically active lone-pair of electrons on the Se(IV) centers may act as a structural directing agents [11] and the asymmetric geometry of ψ-SeO 3 may lead to a noncentrosymmetric structure, thus possessing interesting physical properties such as optical nonlinearity [12,13]. Since the first organic amine templated selenite compound [14] reported by Harrison et al in 2000, a large number of inorganicorganic hybrid metal selenites have been prepared [15][16][17][18][19][20][21][22][23][24], most of which are organic amine containing hybrids in which organic amines exist as cations or sometimes enter the metal-selenite moieties by coordinating to the metals.…”