Abstract |
Syntheses, structures, and electrochemistry of a dialkoxo-bridged diuranyl(VI) compound [(UO2)(2)(L-1)(2)(dimethylformamide)(2)] (1) and a mononuclear-mononuclear cocrystalline compound [(UO2)(2)(L-2)(H2O)subset of(H2O)]center dot[(UO2)(L-2)(H2O)] (2) derived from Schiff base ligands are reported (H2L1 = Schiff base ligand obtained on condensation of 3-ethoxysalicylaldehyde with 2-aminoethanol; H2L2 = N,N -o-phenylenebis(3-ethoxysalicylaldimine)). The compounds 1 and 2 crystallize in the space groups P2(1)/c and P (1) over bar, respectively. Compound 1 is a dialkoxo-bridged dinuclear compound of uranium(VI) containing two deprotonated ligands, [L](2-), two dimethylformamide (dmf) molecules and two UO22+ centers. Three C-H center dot center dot center dot O type hydrogen bonds involving one uranyl oxygen, two dmf hydrogens, and the imine hydrogen link the dinuclear units into a two-dimensional network. Compound 2 is a cocrystal of two mononuclear units, [(UO2)(2)(L-2)(H2O)subset of(H2O)] (unit 1) and [(UO2)(L-2)(H2O)] (unit 2). In unit 1, the non-coordinated water molecule forms hydrogen bonds with oxygens of phenoxo, ethoxy, and coordinated water molecules resulting in the formation of an inclusion product. The overall supramolecular structure of compound 2 is one-dimensional and consists of interlinked self-assembled dimeric unit of unit 1 and unit 2. Cyclic voltammetric measurements reveal that the uranium(VI) center in [(UO2)(2)(L-1)(2)(dimethylformamide)(2)] (1) is reduced quasireversibly at E-1/2 = -773 mV with Delta E-P = 121 mV, while the metal center in [(UO2)(L-2)(H2O)subset of(H2O)]center dot[(UO2)(L-2)(H2O)] (2) is reduced reversibly with E-1/2 =-765 mV with Delta E-P = 68 mV. |