The first two-dimensional organic–inorganic hybrid constructed by oxalate-bridging scandium-substituted Keggin-type silicotungstate and [Cu(en)2]2 + coordination cations

The hydrothermal reactions of Keggin-type silicotungstate with rare-earth–transition-metal (RE–TM) heterometals in the presence of mixed ligands of oxalate and en (en = ethylenediamine) generate a novel two-dimensional (2D) organic–inorganic hybrid oxalate-bridging scandium-substituted silicotungstate. The complex [Cu(en)2(H2O)]2{[Cu(en)2(H2O)]2[Cu(en)2]2[(α-SiW11O39)Sc(H2O)]2(C2O4)}·8H2O (1) has been further characterized by elemental analyses, powder X-ray diffraction (PXRD), IR spectra, thermogravimetric (TG) analyses, and single-crystal X-ray diffraction. X-ray structural analysis reveals that 1 exhibits the dimeric mono-Sc substituted Keggin [Sc(α-SiW11O39)]210 − subunits linked by the oxalate ligand, which further results in the 2D network architecture interconnected by [Cu(en)2]2 + coordination cations. Notably, 1 represents the first oxalate-bridging RE–TM heterometallic hybrid built by lacunary Keggin silicotungstate-supported RE derivatives and [Cu(en)2]2 + coordination cations. Furthermore, the TG curve of 1 displays two steps of slow weight loss in the range of 25–1000 °C.