New Heteropolytungstates Incorporating Dioxouranium(VI). Derivatives of α-[SiW 9 O 34 ] 10− , α-[AsW 9 O 33 ] 9− , γ-[SiW 10 O 36 ] 8− , and [As 4 W 40 O 140 ] 28−

摘要: Reaction of uranium salts with several lacunary polyoxotungstate anions yields four new heteropolyanion assemblies in which the atoms occupy pentagonal bipyramidal coordination polyhedra. Treatment A,α-[SiW9O34]10− UO2(NO3)2 leads to Na14[Na2(UO2)2(SiW9O34)2]⋅38H2O (1, Monoclinic, P21/c, a=16.5719(8) A, b=14.1689(7) c=21.2528(10) β=111.6670(10)°, V=4786.6(4) A3, Z=2) proves be isostructural analogous derivative [PW9O34]9− reported previously. Solutions 1 exhibit 5-line W-NMR spectrum expected for structure C i point symmetry. The salt (NH4)17[(UO2)3(H2O)4As3W26O94]⋅16H2O (2, Orthorhombic, Pnma, a=40.1747(2) b=18.25840(10) c=18.0817(2) V=13263.4(2) Z=4) was isolated 64% yield from a reaction B,α-[AsW9O33]9−. anion 2 has s symmetry and contains one α-AsW9O33 two novel β-AsW8O30 units linked by UO2+ 2 groups; an additional WO6 links AsW8 fragments. Spectrophotometric titration UCl4 sodium [As4W40O140]28− indicated formation 4:1 U:As4W40 complex. During attempts isolate crystalline product this became oxidized guanidinium [Na(UO2)3(OH)(H2O)6As4W40O140(WO)]18− (3, Fdd2, a=54.848(3) b=80.809(4) c=20.2874(2) V=89919(7), Z=16) isolated. partially disordered 3 shows S2 adjacent sites As4W40 occupied three UO5 WO5 A tetrameric assembly γ-SiW10 groups occurs [{M(OH2)}4(UO2)4(OH)2(SiW10O36)4]22− (lithium salt, M=Na, 4a, tetragonal, P42/nmc, a=b=26.5285(2) c=15.0463(2) V=10589.0(2) Z=2; sodium-potassium M=K, 4b, orthorhombic, Fddd, a=24.180(5) b=31.696(6) c=58.012(12) V=44460(15) Z=8). Tungsten-183 NMR spectra show slow transformation (1:1:1:1:1) 4a species giving 6-line (2:2:2:1:2:1). latter complex not been successfully