BA7FE6F32 CENTER-DOT 2H(2)O - ORIGINAL ISOLATED TRIMERS [FE3F16](7-) IN A NEW DEFECTIVE JARLITE-TYPE COMPOUND

Ba7Fe6F32. 2H(2)O was prepared from HF aqueous solution in a teflon bo mb (Berghof) at 180 degrees C. A partial exchange F-/OH- can be realiz ed in more diluted HF medium and leads to Ba7Fe6F32-x(OH)(x) .2H2O. Th e compounds crystallize in the monoclinic system, space group C2/m (Z = 2) with a = 17.023(1) Angstrom, b = 11.482(1)Angstrom, c = 7.624(1) Angstrom, beta = 101.13(1)degrees for x = 0 and a = 17.036(2) Angstrom , b = 11.489(1)Angstrom, c = 7.620(2) Angstrom, beta = 101.48(1)degree s for x approximate to 5.3. The structures were determined from 2256 a nd 1343 independent reflections for x = 0 and x approximate to 5.3 res pectively, collected with a Siemens AED2 four-circle diffractometer wi th the MoK alpha radiation (R = 0.0235 and R(W) = 0.0240 for x = 0 and R = 0.0324 and R(W) = 0.0335 for x approximate to 5.3). The structure , closely related to that of the Jarlite-type, is built up from isolat ed octahedra trimers [Fe3F16](7-), connected together by Ba2+-cations. The location of anions and water molecules is discussed from bond val ence calculations. Magnetic and Mossbauer studies are reported and dis cussed.