Studies of Syntheses and Reactions of Layred Antimony Compounds with Anions between the Layrs

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1. A new layr compound (Sb_4O_5)(ReO_4)_4 has been prepared by thermal decomposition of a hydrate compound SbOReO_2・2H_2O in a sealed silica tube and its structure was determined by single-crystal X-ray diffraction. The structure contains cationic layrs of (Sb_4O_5)^<2+> extending along the 010 plane in which each antimony atom has three coordinating oxygen atoms in a trigonal-pyramid geometry. These SbO_3 pyramids share their edges and apices to form a two-dimensional layr. Tetrahedral perrhenate ions are between these cationic layrs. Antimony atoms have also long bonds (2.5-2.75*) with the oxygen atoms of the perrhenate ions, and these bonds presumably sustain the three-dimensional structure. Trials to substitute the perrhenate ions with other anions were unsuccessful. Comparison of the structures of the compounds with cationic antimony oxide layrs indicates the importance of the interactions between the anions and the cationic layrs for these structures.2. A new compound SbRe_2O_6 with a Re-Re bond has been prepared by a reaction of SbOReO_4・2H_2O with rhenium metal in a sealed silica tube. X-ray structure determination has shown that the structure is made of Re_2O_6 layrs which are slices of the rutile structure along the 101 plane and antimony atoms connecting the layrs. The Re_2O_6 layrs contain pairs of ReO_6 octahedra sharing an edge where the Re-Re distance is 2.519 (1)*. Though in BiRe_2O_4 having similar structure oxygen atoms in the Re_2O_6 layrs is disordered, SbRe_2O_6 has ordered stacking of the layrs in the sequence of ABAB.