Mild Hydrothermal Synthesis and Structural Determination of Two Layered, Structurally Related Inorganic-Organic Hybrid Vanadates with Nickel(II) and Tris(2-aminoethyl)amine

2D Ni-2(C6H19N4)(2)(V6O18)center dot 2H(2)O (1) and Ni-2(C6H19N4)(2)(V6O18)center dot H2O (2) are inorganic-organic hybrid compounds that have been synthesised under hydrothermal conditions. Crystalline aggregates composed of both compounds were obtained and structural characterisation was subsequently carried out using single crystalline fragments of these aggregates. Optimisation of the synthetic conditions allowed us to obtain 1 as a polycrystalline powder. The crystal structures of 1 and 2 were solved using single-crystal X-ray diffraction data. Both compounds are structurally related, as the layers from which they are built have the same composition and connectivity in both structures. The main differences between them are the layer stacking and water contents. UV/Vis spectroscopy of 1 shows the characteristic features of the Ni(II)d(8) cation in slightly distorted octahedral symmetry. From the temperature-dependent magnetic susceptibility measurements the parameter D/hc = -3.75 cm(-1) was obtained. Phase I undergoes a reversible structural transformation at approximately 60 degrees C as a result of the dehydration process. This dehydration gives rise to a decrease in the unit cell volume. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)