NiII36-Containing 54-Tungsto-6-Silicate: Synthesis, Structure, Magnetic and Electrochemical Studies

The 36-Ni-II-containing 54-tungsto-6-silicate, [Ni-36(OH)(18)(H2O)(36)(SiW9O34)(6)](6-) (Ni-36) was synthesized by a simple one-pot reaction of the Ni-2-pivalate complex [Ni-2(mu-OH2)(O2CCMe3)(4)(HO2CCMe3)(4)] with the trilacunary [SiW9O34](10-) polyanion precursor in water and structurally characterized by a multitude of physicochemical techniques including single-crystal XRD, FTIR, TGA, elemental analysis, magnetic and electrochemical studies. Polyanion Ni-36 comprises six equivalent {(Ni6SiW9)-Si-II} units which are linked by Ni-O-W bridges forming a macrocyclic assembly. Magnetic studies demonstrate that the {Ni-6} building blocks in Ni-36 remain magnetically intact while forming a hexagonal ring with antiferromagnetic exchange interactions between adjacent {Ni-6} units. Electrochemical studies indicate that the first reduction is reversible and associated with the W-VI/V couple, whereas the second reduction is irreversible attributed to the Ni-II/0 couple.

Automated summary

This article describes the synthesis of a nickel and tungsto-silicate complex and its structural characterization using various physicochemical techniques. The analysis reveals that the complex contains six equivalent {(Ni6SiW9)-Si-II} units linked by Ni-O-W bridges to form a macrocyclic assembly. Magnetic studies show that the building blocks remain magnetically intact with antiferromagnetic exchange interactions between adjacent units, while electrochemical studies indicate reversible and irreversible reduction processes associated with different couples.