Syntheses and structures of one- and two-dimensional organic anorganic hybrid rare earth derivatives based on monovacant Keggin-type polyoxotungstates

Three novel organic-inorganic hybrid monovacant Keggin-type silicotungstates and germanotunostates containing lanthanide(III) cations with 1D and 2D infinitely extended structures, [Sm(H2O)(6)](0.25)[Sm(H2O)(5)](0.25)H-0.5{Sm(H2O)(7)[Sm(H2O)(2)(DMSO)(alpha-SiW11O39)]}center dot 4.5H(2)O (DMSO = dimethyl sulfoxide) (1), [Dy(H2O)(4)](0.25)[Dy(H2O)(6)](0.25)H-0.5{Dy(H2O)(7)[Dy(H2O)(2)(DMSO)(alpha-GeW11,O-39)]}center dot 5.25H(2)O (2), and H{[Sm(H2O)(5.5)(DMF)(0.5)](2)[Sm(H2O)(2)(DMF)][Sm(H2O)(3)(alpha-SiW11O39)](2)} (DMF = N,N-dimethyl formamide) (3), have been synthesized in aqueous solution under moderate conditions and further characterized by elemental analyses, inductively coupled plasma (ICP) analyses, IR, UV spectra, and X-ray diffraction. Compounds 1 and 2 reveal the one-dimensional chain infinitely extended structure, while compound 3 represents the first example of a two-dimensional network structure formed by the monovacant Keggin-type [alpha-SiW11O39](8-) chain through the linkage of rare earth metal-organic coordination cations. From thermogravimetric (TG/DTA) analyses, the polyanion frameworks of 1 and 2 retain a comparatively good thermal stability. Variable temperature magnetic susceptibility indicates that compounds 1 and 3 obey the Curie-Weiss law in the higher temperature region from 130 to 300 K, while in the lower temperature region from 2 to 130 K they show the occurrence of strong spin-orbital coupling interactions and very weak ferromagnetic responses.