Synthesis, Structure, and Magnetic Properties of Amine-Templated Open-Framework Nickel(II) Sulfates

Two organically templated nickel sulfates of the compositions [C4N2H12][Ni3F2(SO4)3(H2O)2] (I) and [C4N2H12][Ni2F4(SO4)H2O] (II) with open architectures have been synthesized under hydro/solvothermal conditions in the presence of piperazine. I has a layered structure formed by sinusoidal chains comprising hexameric units, whereas II has a three-dimensional structure with 10-membered channels. The layered Ni(II) sulfate, I, is ferrimagnetic, exhibiting hysteresis at low temperatures. The three-dimensional Ni(II) sulfate, II, is essentially paramagnetic. We have also obtained layered compounds isostructural with I containing other amines.