Dioxouranium complexes as ligand. Synthesis and characterization of sandwich-type polyoxometalates [X2W18(UO2)2{(H2O)3M}2O68]10 (X = AsV and PV) (M= CoII, CuII, MnII, NiII and ZnII)

摘要

The title complexes are synthesized by the reaction of an unusual ligand of [K2P2W18(UO2)2O68]12 (1) and [KAs2W18(UO2)2O68]13 (2) with divalent metal ions of CoII, CuII, MnII, NiII and ZnII in 1:2 mole ratio and are characterized by elemental analysis, IR, 31P NMR, UV–Vis spectroscopy, TGA, and single crystal structure analysis. Crystals of [P2W18(UO2)2{(H2O)3Co}2O68]10 (1a) and [As2W18(UO2)2{(H2O)3Cu}2O68]10 (2b) are orthorhombic space group Cmca. Both 1a and 2b have structures in which two [M(H2O)3] (M= CoII, CuII) and two UO2 groups are sandwiched between two symmetry equivalent XW9O34 9 (XW9) (X = P, As) units in a virtual Ci symmetry. In solution, 1a and [P2W18(UO2)2{(H2O)3Zn}2O68]10 (1d) give two-line P NMR spectra that are consistent with a Cs symmetry structures so, are not consistent with the solid-state structures. The sodium salts of them give one-line P NMR spectra and are consistent with the Ci symmetry of solid-state structures. The uranium atoms have pentagonal-bipyramidal coordination, achieved by three equatorial bonds to the one XW9 and two bonds to the other. TheMatoms have octahedral or square pyramidal coordination, but only one bond to the one XW9 and one bond to the other.