The Preparation and Characterization of Two New Isomorphous Binuclear Heteropolytungstate Anions

Abstract

The ammonium salts of [NiCoW₁₁O₃₆FH₂]^7- and [CuMnW₁₁O₄₀H₂]^8-have been isolated in the crystalline form. The cubic blue crystals of (NH₄)₆NaNiCoW₁₁O3gFH₂10H₂O crystalize in the cubic space group Pm3m with a = 11.170 Å. Other evidence from analytical results, FABMS, spectroscopy (Vis., I.R.), polarography, and X-ray powder patterns have shown that the above two anions are isomorphous. The structure of the anion is a modification of the well known “Keggin” structure. The first transition metal ion in the above formulas is thought to occupy the octahedral site; the second is thought to occupy the inner tetrahedral cavity. The two are bridged by an oxide or fluoride ion.