A polyoxoniobate based on dimeric hexanionbate: [Cu(en)2]4{[Nb6O19H2]K(H2O)5}2 center dot (H2en) center dot 17H2O

A polyoxoniobate, [Cu(en)2]4{[Nb6O19H2]K(H2O)5}2 (H2en) 17H2O (en = ethylenediamine) (1), has been synthesized and characterized by elemental analysis, IR, XPS, TGA, and single-crystal X-ray diffraction. Compound 1 crystallizes in the triclinic system, space group P1, with a = 12.3533(16) angstrom, b = 12.7188(16) angstrom, c = 29.626(4) angstrom, = 93.235(2)degrees, = 96.094(1)degrees, = 106.098(2)degrees, V = 4429.0(10) angstrom 3, Z = 2. The polyoxoanion is composed of a Lindqvist-type [Nb6O19H2]6- dimer bi-bridged via two K+. K+ is 10-coordinate with 10 oxygens, three from one [Nb6O19H2]6-, one from a terminal oxygen of another [Nb6O19H2]6- moiety, and the other six from water molecule. Adjacent dimeric polyoxoanions are linked to form an infinite 1-D chain via O-H center dot center dot center dot O hydrogen-bonding interactions which exist between the two water trimers and the dimeric polyoxoanions.