Synthesis and crystal structure of bis-[μ-,-bis-(2-amino-eth-yl)ethane-1,2-di-amine]-bis-[,-bis-(2-amino-eth-yl)ethane-1,2-di-amine]-μ-oxido-hexa-μ-oxido-octa-μ-oxido-tetra-oxido-tetra-nickel(II)hexa-tantalum(V) nona-deca-hydrate.

Reaction of K{TaO}·16HO with [Ni(tren)(HO)Cl]Cl·HO in different solvents led to the formation of single crystals of the title compound, [NiTaO(CHN)]·19HO or {[Ni(κ-tren)(μ-κ-tren)]TaO}·19HO (tren is ,-bis-(2-amino-eth-yl)-1,2-ethanediamine, CHN). In its crystal structure, one Lindqvist-type anion {TaO} (point group symmetry ) is connected to two Ni cations, with both of them coordinated by one tren ligand into discrete units. Both Ni cations are sixfold coordinated by O atoms of the anion and N atoms of the organic ligand, resulting in slightly distorted [NiON] octa-hedra for one and [NiON] octa-hedra for the other cation. These clusters are linked by inter-molecular O-H⋯O and N-H⋯O hydrogen bonding involving water mol-ecules into layers parallel to the plane. Some of these water mol-ecules are positionally disordered and were refined using a split model. Powder X-ray diffraction revealed that a pure crystalline phase was obtained but that on storage at room-temperature this compound decomposed because of the loss of crystal water mol-ecules.