THE PREPARATION AND CHARACTERIZATION OF THE FLUORINATED DINUCLEAR HETEROPOLYOXOTUNGSTATE ANION WITH LOOSELY COORDINATED WATER MOLECULE [(H2O)CUO5ZNO4W11O28F2](8-)

The ammonium salt of the fluorinated heteropolyanion, [(H2O)CuO5ZnO4W1 1O28F2](8-), has been isolated in the crystalline form. The X-ray powd er pattern of this compound is similar to that of (NH4)(8)[CO2W11O40H2 ]. xH(2)O for which a single crystal structure has been solved(10). Th e anion has the distorted Keggin structure. Evidence from the visible spectrum indicates that the Cu2+ ion occupies the octahedral position vacated by the missing W6+ ion. Accordingly, we assigned the Zn2+ ion to occupy the inner tetrahedral cavity in the Keggin structure. Other evidence from elemental analyses, thermal studies, infrared spectrosco py, ultraviolet-visible spectroscopy, and cyclic voltammetry support t hat the structure is a modification of the well known Keggin structure . It appears that the water molecule coordinated to the Cu2+ ion in th e heteropolyanion could be removed easily either by slight heating or exposure to a drying agent. It could also be replaced by suitable liga nds such as NH3, pyridine, pyrazine, SCN-, and NO2-. Evidence from vis ible and IR spectra support this replacement.