Two-dimensional layer architecture assembled by Keggin polyoxotungstate, Cu(II)-EDTA complex and sodium linker: Synthesis, crystal structures, and magnetic properties

Reaction of Keggin polyoxotungstate with copper(II)-EDTA (EDTA=ethylenediamine tetraacetate) complex under mild conditions led to the formation of hybrid inorganic-organic compounds Na{sub 4}(OH)[(Cu{sub 2}EDTA)PW{sub 12}O{sub 40}].17H{sub 2}O (1) and Na{sub 4}[(Cu{sub 2}EDTA)SiW{sub 12}O{sub 40}].19H{sub 2}O (2). The single-crystal X-ray diffraction analyses reveal their two structural features: (1) one-dimensional chain structure consisting of Keggin polyoxotungstate and copper(II)-EDTA complex; (2) Two-dimensional layer architecture assembled by the one-dimensional chain structure and sodium linker. The results of magnetic measurements in the temperature range 300-2 K indicated the existence of ferromagnetic exchange interactions between the Cu{sup II} ions for both compounds. In addition, TGA analysis, IR spectra, and electrochemical properties were also investigated to well characterize these two compounds. - Graphical abstract: Two new polyoxometalate-based hybrids, Na{sub 4}(OH)[Cu{sub 2}(EDTA)PW{sub 12}O{sub 40}].17H{sub 2}O (1) and Na{sub 4}[Cu{sub 2}(EDTA)SiW{sub 12}O{sub 40}].19H{sub 2}O (2), have been synthesized and structurally characterized, which consist of one-dimensional chain structure assembled by Keggin polyoxotungstate and copper(II)-EDTA complex. The chains are further connected to form two-dimensional layer architecture assembled by the one-dimensional chain structure and sodium linker.