The reaction of uranyl nitrate with asymmetric [3O, N] Schiff base ligands in the presence of base yields dinuclear uranyl complexes, [UO2(HL1)]2.DMF (1), [UO2(HL2)]2.2DMF.H2O (2), and [UO2(HL3)]2.2DMF (3) with 3-(2-hydroxybenzylideneamino)propane-1,2-diol (H3L1), 4-((2,3-dihydroxypropylimino)methyl)benzene-1,3-diol (H3L2), and 3-(3,5-di-tert-butyl-2-hydroxybenzylideneamino)propane-1,2-diol (H3L3), respectively. All complexes exhibit a symmetric U2O2 core featuring a distorted pentagonal bipyramidal geometry around each uranyl center. The hydroxyl groups on the ligands are attached to the uranyl ion in chelating, bridging, and coordinate covalent bonds. Distortion in the backbone is more pronounced in 1, where the phenyl groups are on the same side of the planar U2O2 core. The phenyl groups are present on the opposite side of U2O2 core in 2 and 3 due to electronic and steric effects. A similar hydrogen-bonding pattern is observed in the solid-state structures of 1 and 3 with terminal hydroxyl groups and DMF molecules, resulting in discrete molecules. Free aryl hydroxyl groups and water molecules in 2 give rise to a two-dimensional network with water molecules in the channels of an extended corrugated sheet structure. Compound 1 in the presence of excess Ag(NO3) yields {[(UO2)(NO3)(C6H4OCOO)](NH(CH2CH3)3)}2 (4), where the geometry around the uranyl center is hexagonal bipyrimidal. Two-phase extraction studies of uranium from aqueous media employing H3L3 indicate 99% reduction of uranyl ion at higher pH.

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Under identical conditions, the reaction of 2-aminoethanethiol hydrochloride with HgX(2) (X = Cl and Br) in water yielded discrete hexanuclear [Hg(6)Cl(8)(SCH(2)CH(2)NH(3))(8))]Cl(4).4H(2)O (1) and nonanuclear [Hg(9)Br(15)(SCH(2)CH(2)NH(3))(9)](Cl(0.8)Br(0.2))(3) (2) complexes with unusual coordination environments. Compound 1 crystallizes as triclinic with a = 9.434(2) Angstroms, b = 10.999(2) Angstroms, c = 13.675(7) Angstroms, alpha = 92.9(7) degrees, beta = 105.2(7) degrees, and gamma = 96.9(7) degrees, whereas 2 is monoclinic with a = 14.162(3) Angstroms, b = 8.009(16) Angstroms, c = 19.604(4) Angstroms, alpha = gamma = 90.0 degrees, and beta = 92.7(3) degrees. In both cases, it is observed that the halide creates the secondary structure around trinuclear units (dimer in 1 and trimer in 2) through Hg-X bonding. Two independent types of Hg atoms (four- and five-coordinate in 1) and (three- and four-coordinate in 2) are observed. The geometry around Hg is quite variable with bridging thiolate and both bridging and terminal halides. The angles around Hg associated with the S atoms are more obtuse than expected from mercury(II) thiolates with a coordination number of more than 2. Intermolecular hydrogen bonding involving NH(3)(+), water molecules, and the halide atoms is responsible for the three-dimensional network in both compounds. Relatively short Hg...Hg interactions in 1 (3.797 and 3.776 Angstroms) and in 2 (3.605 and 3.750 Angstroms) are also observed. The compounds have been characterized with the help of (1)H and (13)C NMR, UV-Vis, infrared, Raman, and mass spectrometry, thermogravimetric analysis, and single X-ray crystallography.

The reaction of 2-aminoethanethiol hydrochloride with Hg(2)Cl(2) in water yielded elemental mercury and one-dimensional polynuclear compounds [{Hg(3)Cl(5)(SCH(2)CH(2)NH(3))(3)}Cl](n) and [HgCl(SCH(2)CH(2)NH(2))(H(2)O)(2)](n) (2). The coordination environment around Hg in 1 and 2 is quite variable despite similar reaction conditions. The formation of a five-membered S/N chelate in 2 can be attributed to the use of base to produce a neutral ligand. Three independent types of Hg atoms, both three- and four-coordinate are observed in 1, whereas in 2, the Hg atom is tetracoordinate with S, N and Cl atoms in the primary coordination sphere. Despite distinct structural chemistry, the coordination environments in 1 and 2 are fairly similar with repeating units connected with bridged thiolate S atoms in addition to a terminal Cl attached to Hg. Intermolecular hydrogen-bonding involving amine protons, Cl and water molecules are responsible for a three-dimensional network in both 1 and 2. A short Hg...Hg distance of 3.564 A, indicates the presence of a mercurophilic interaction in 1. The compounds have been characterized by (1)H and (13)C NMR, UV-Vis, FT-IR, Raman, mass spectrometry, TGA and single X-ray crystallography.

Combination of 2-aminoethanethiol hydrochloride and HgI2 in water in the presence of a base yielded a cyclic molecular structure, [Hg4I4(SCH2CH2NH2)4] (1). For the same reaction in the absence of the base, a similar structure with protonated amines was expected; however, polymeric [Hg4I8(SCH2CH2NH3)2]n.nH2O2 was formed instead. The structures are quite variable despite similar reaction conditions. For instance, there is an additional Hg-N interaction in 1 due to the use of base. The environment around tetracoordinate Hg in 1 is comprised of S, N, and I atoms, with the ligand forming a five-membered chelate and the I atoms present alternate to each other. In the repeating unit of 2, three independent types of Hg atoms are observed, with HgSI3, HgS2I2, and HgI4 bonding environments that have both bridging and terminal I atoms. A simple mechanistic pathway for the formation of 1 and 2 is proposed that includes the presence of three- and four-coordinate Hg intermediates in the solution. Intermolecular hydrogen bonding involving N, I, and S in 1 and N, I, and O atoms in 2 create extended three-dimensional networks. The shortest Hg... Hg distances are found to be intrachain in the range 3.938-3.962 A and indicate no interaction between these atoms. The solution studies (UV-vis and NMR) along with solid-state (IR, Raman, and X-ray) studies for 1 and 2 confirm retention of the structural configuration in the solution. The thermal study of 2 indicates that degradation of the complex occurs in a single step, in contrast to 1, which takes a more complicated decomposition pathway.