Cation effects on the formation of the one-dimensional uranyl iodates A2[(UO2)3(IO3)4O2] (A = K, Rb, Tl) and AE[(UO2)2(IO3)2O2] (H2O) (AE = Sr, Ba, Pb)

The reactions of UO3 and I2O5 with RbCl, TlCl, SrCl2, or Pb(NO3)(2) at 200 degreesC for 3 days in aqueous media result in the formation of A(2)[(UO2)(3)(IO3)(4)O-2] (A = Rb (1), Tl (2)) and AE[(UO2)(2)(IO3)(2)O-2] (H2O) (AE = Sr (3), Pb, (4)). Compounds 1 and 2 are isostructural with K-2[(UO2)(3)(IO3)(4)O-2], which has been prepared by similar methods. These compounds are composed of (1)(infinity)[(UO2)(3)(IO3)(4)O-2](2-) chains built from the edge-sharing of UO7 pentagonal bipyramids and UO6 octahedra. Compounds 3 and 4 are isostructural with Ba[(UO2)(2)(IO3)(2)O-2] H2O), consisting of one-dimensional (1)(infinity)[(UO2)(2)(IO3)(2)O-2](2-) ribbons formed from the edge-sharing of distorted UO, pentagonal bipyramids. The iodate groups in these compounds adopt both bridging and monodentate binding modes and further serve to terminate the edges of the uranium oxide chains. The alkali metal, alkaline-earth metal, and main group cations separate the chains or ribbons in these compounds forming contacts with terminal oxygen atoms from the iodate ligands. Crystallographic data (193 K, MoK alpha, lambda = 0.71073): 1, triclinic, space group P (1) over bar, a = 7.0834(8) Angstrom, b = 7.8935(9) Angstrom, c = 9.092(1) Angstrom, alpha = 91.741(2)degrees, beta =105.110(2)degrees, gamma = 92.214(2)degrees, Z =1, R(F) = 3.39% for 134 parameters with 1978 reflections with I > 2 sigma (I); 2, triclinic, space group P (1) over bar, a = 7.0602(6) Angstrom, b = 7.9475(6) Angstrom, c = 9.0175(7) Angstrom, alpha = 91.867(1)degrees, beta = 105.595(1)degrees, gamma = 91.577(1)degrees, Z = 1, R(F) = 3.12% for 134 parameters with 2220 reflections with I > 2 sigma (1); 3, monoclinic, space group P2(1)/c, a = 7.8140(5) Angstrom, b = 6.9425(4) Angstrom, e = 21.434(1), beta= 99.324(1)degrees, Z = 4, R(F) = 4.20% for 164 parameters with 2533 reflections with I > 2 sigma (I); 4, monoclinic, space group P2(1)/c, a = 7.8441(5) Angstrom, b = 6.9328(4) Angstrom, c = 21.340(1), beta = 99.062(1)degrees, Z = 4, R(F) = 3.37% for 164 parameters with 1965 reflections with I > 2 sigma (1). (C) 2001 Academic Press.