Inorganic Chemistry, Vol.41, No.21, 5495-5501, 2002
Expanding the remarkable structural diversity of uranyl tellurites: Hydrothermal preparation and structures of K[UO2Te2O5(OH)], Tl-3{(UO2)(2)[Te2O5(OH)](Te2O6)}center dot 2H(2)O, beta-Tl-2[UO2(TeO3)(2)], and Sr-3[UO2(TeO3)(2)](TeO3)(2)
The reactions of UO2(C2H3O2)(2).2H(2)O with K2TeO3.H2O, Na2TeO3 and TlCl, or Na2TeO3 and Sr(OH)(2).8H(2)O under mild hydrothermal conditions yield K[UO2Te2O5(OH)] (1), Tl-3{(UO2)(2)[Te2O5(OH)](Te2O6)].2H(2)O (2) and beta-Tl-2[UO2(TeO3)(2)] (3), or Sr-3[UO2(TeO3)(2)](TeO3)(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 UO6 units span between one-dimensional chains of corner-sharing, square pyramidal TeO4 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 TeO4 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 (1)(infinity)[UO2(TeO3)(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 TeO32- anions present. Crystallographic data: 1, orthorhombic, space group Cmcm, a = 7.9993(5) Angstrom, b = 8.7416(6) Angstrom, c = 11.4413(8) Angstrom, Z = 4; 2, orthorhombic, space group Pbam, a = 10.0623(8) Angstrom, b = 23.024(2) Angstrom, c = 7.9389(6) Angstrom, Z = 4; 3, monoclinic, space group P2(1)/n, a = 5.4766(4) Angstrom, b = 8.2348(6) Angstrom, c = 20.849(3) Angstrom, beta = 92.329(1)degrees, Z = 4; 4, monoclinic, space group C2/c, a = 20.546(1) Angstrom, b = 5.6571(3) Angstrom, c = 13.0979(8) Angstrom, beta = 94.416(1)degrees, Z = 4.