W-type dimericl architecture based on {Ge4Nb16Cu(en)} unit

A novel organic-inorganic hybrid germanoniobate with the molecular formula of K2NaH9[Cu(en)2(H2O)2]3[Cu (en)2][{Cu(en)(H2O)}2{Ge4Nb16O54(OH)2(Cu(en))}2]center dot 12H2O (1, en = ethanediamine) was synthesized by the combination of hydrothermal and diffusion synthetic strategy, which was structurally characterized by single crystal X-ray diffraction, IR spectra, powder X-ray diffraction, thermogravimatric analysis and UV/Vis diffuse reflectance spectra. In compound 1, the W-type polyoxoanion [{Cu(en)(H2O)}2{Ge4Nb16O54(OH)2(Cu(en))}2]20-is composed of two {Ge4Nb16O54(OH)2(Cu(en))} subunits bridged by two {Cu(en)(H2O)} groups, which repre-sents the first example of transition-metal-bridged germanoniobate-based dimer. Besides, organo-amines play an important role in the construction of this compound.