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

A polyoxoniobate, [Cu(en)₂]₄{[Nb₆O ₁₉H₂]K(H₂O)₂}₂ (H ₂en) 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 P1̄, with a = 12.3533(16)Ä , b = 12.7188(16)Ä , c = 29.626(4)Ä, α= 93.235(2)°, β= 96.094(1)°, γ= 106.098(2)°, V = 4429.0(10)ij, Z = 2. The polyoxoanion is composed of a Lindqvist-type [Nb₆O₁₉H ₂]^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 O hydrogen-bonding interactions which exist between the two water trimers and the dimeric polyoxoanions.