Synthesis and crystal structure of barium thioborate Ba7(BS3)4S

The thioborate phase Ba-7(BS3)(4)S was synthesized from solid state reaction and its crystal structure determined by single crystal X-ray diffraction analysis. It crystallizes in the monoclinic space group C2/c (No. 15) with a = 10.1750(15) Angstrom, b = 23.970(4) Angstrom, c = 10.1692(15) Angstrom, beta = 90.095(2)degrees, and Z= 4. The structure consists of isolated trigonal planar (BS3)(3-) anions, and isolated S2- anions and Ba2+ cations. The additional sulfur anions have five-fold barium coordination, while the barium cations are coordinated by eight or nine sulfur atoms. Powder X-ray diffraction patterns from a bulk sample are compared to the calculated diffraction pattern from the single crystal structural analysis, and there is excellent agreement in general. The vibrational modes of the isolated (BS3)(3-)units were measured from Raman scattering and IR absorption spectra, and the frequencies agree very well with those found for similar orthothioborate phases.