Heptanickel(II) double-cubane core in wells-dawson heteropolytungstate, [Ni7(OH)6(H2O)6(P2W15O56)2]16−

Abstract

The hepta-Ni2+-containing 30-tungsto-4-phosphate(V) [Ni7(OH)6(H2O)6(P2W15O56)2]16− (1) has been synthesized in aqueous, slightly basic medium under conventional reaction conditions, and charactarized via different physical methods. Single-crystal XRD showed that 1 consists of a corner-fused double-cubane {Ni7(OH)6(H2O)6}8+ fragment sandwiched by two trilacunary [P2W15O56]12− units. Polyanion 1 is solution-stable as shown by 31P NMR. Ferromagnetic coupling interaction between the 7 paramagnetic centers of the double-cubane core in 1 with a S = 7 ground state was demonstrated. Electrochemical studies were also performed on 1.