Increasing Complexity in the Uranyl Ion − Kemp’s Triacid System: From One- and Two-Dimensional Polymers to Uranyl − Copper(II) Dodeca- and Hexadecanuclear Species - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Crystal Growth & Design Année : 2014

Increasing Complexity in the Uranyl Ion − Kemp’s Triacid System: From One- and Two-Dimensional Polymers to Uranyl − Copper(II) Dodeca- and Hexadecanuclear Species

Résumé

Kemp’s triacid (cis,cis-1,3,5-trimethylcyclohexane-1,3,5-tricarboxylic acid, LH3) has recently been shown to be a versatile ligand for the uranyl ion, with the presence of additional nickel(II) cations allowing isolation of nanotubular and cage species in particular. The high sensitivity of the uranyl−LH3 system to variations in the experimental conditions was the incentive for the present investigation of different solvents as organic components in solvo-hydrothermal synthesis methods and of different additional species (metal cations, 2,2′-bipyridine). Reaction of LH3 with uranyl ions under purely hydrothermal conditions gives [UO2(LH2)2(H2O)2]·2H2O (1), an unremarkable mononuclear complex. In the presence of manganese nitrate and in water−THF or water−methanol, respectively, the complexes [Hbipy][UO2(L)]·0.5H2O·0.25THF (2) and [(UO2)3(MeL)2(OH)2(H2O)]·8MeOH (3) were obtained; 2 is a two-dimensional (2D) species, while 3 is one-dimensional (1D) and contains the monoester derivative of LH3, formed in situ. Another 2D compound, [UO2Tb(L)2H(H2O)2] (4), crystallizes in the presence of terbium(III) nitrate. The three complexes [(UO2)8(L)6H2(H2O)6]·H2O (5), [(UO2)8(L)6H2(H2O)6]·3H2O (6), and [Cu2(C2O4)(bipy)2(THF)2][(UO2)8(L)6H- (H2O)6]2·4H2O·7THF (7), which were obtained in the presence of copper(II) or nickel(II) cations, all contain homometallic octanuclear cage-like species analogous to that previously reported. The most interesting complexes in this series, [(UO2)8Cu4(L)8(H2O)16]·9H2O (8) and [(UO2)10Cu6(L)10(OH)2(H2O)7] (9), were obtained together in water−THF and in the presence of copper(II) cations. Compound 8 is a dodecanuclear metallacycle comprising four (UO2)2Cu trinuclear subunits, in which the central copper atom is bound to two uranyl oxo groups, arranged in helical geometry. Compound 9 is a large, hexadecanuclear cage-like species devoid of any crystallographic symmetry. In both 8 and 9, uranyl ions are topologically sufficient for the formation of the cyclic or cage molecules, and the hydrated copper ions are located inside. The curved shape of the three-pronged Kemp’s tricarboxylate ligand appears well suited to the formation of closed species (nanotubes, rings, and cages), which are in all cases coated on the outside by the hydrophobic parts of the ligands.
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hal-01157648 , version 1 (28-05-2015)

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Pierre Thuéry. Increasing Complexity in the Uranyl Ion − Kemp’s Triacid System: From One- and Two-Dimensional Polymers to Uranyl − Copper(II) Dodeca- and Hexadecanuclear Species. Crystal Growth & Design, 2014, 14, pp.2665−2676. ⟨10.1021/cg500353k⟩. ⟨hal-01157648⟩
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