Synthesis, Magnetism, and Electrochemistry of the Ni14- and Ni5-Containing Heteropolytungstates [Ni14(OH)6(H2O)10(HPO4)4(P2W15O56)4]34- and [Ni5(OH)4(H2O)4(β-GeW9O34)(β-GeW8O30(OH))]13-

The two Ni2+-containing heteropolytungstates [Ni-14(OH)(6)(H2O)(10)(HPO4)(4)(P2W15O56)(4)](34-) (Ni-14) and [Ni-5(OH)(4)(H2O)(4)(beta-GeW9O34)(beta-GeW8O30(OH))](13-) (Ni-5) have been successfully synthesized in aqueous, basic media under conventional reaction conditions, and they were characterized by single-crystal X-ray diffraction, IR spectroscopy, thermogravimetric and elemental analyses, electrochemistry, and magnetic studies. The cyclic voltammetry (CV) patterns of Ni-14 and Ni-5 showed chemically reversible multielectronic waves for slow scan time scales. For Ni-14, an important acidity inversion effect between its reduced forms was observed. Magnetic studies revealed dominant ferromagnetic interactions among the nickel(II) ions in both polyanions.