POLYSULFIDE LIGANDS IN SOLID-STATE ANTIMONY COMPOUNDS - ISOLATION AND STRUCTURAL CHARACTERIZATION OF CS2SB4S8 AND CSSBS6

CS2Sb4S8 and CsSbS6 were synthesized by reacting Sb with a Cs2Sx flux. An investigation of the Sb/CS2Sx system at 260 and 280-degrees-C revealed the presence of two new ternary sulfides, CS2Sb4S8 (I) (67% yield) and CsSbS6 (II) (69% yield), respectively. Red-orange CS2Sb4S8 crystallizes in the triclinic P1BAR space group (No.2) with a = 6.743(1) angstrom, b = 9.577(2) angstrom, c = 6.397(l) angstrom, a = 91.63(1)-degrees, beta = 104.83(1)-degrees, gamma = 80.57(1)-degrees, V = 392 angstrom3, Z = 1, and d(calc) = 4.27g/cm3; number of data with F(o)2 > 3sigma(F(o)2) 1889, number of variables 65, 2theta(max) = 60-degrees. The final R/R(w) = 3.2/4.9. The structure of I consists of [Sb4S6] units that are assembled into chains in the a direction. The chains are connected by S22-bridging units to form layers that are parallel to the (011) crystallographic plane. The layers are connected by Sb-S interactions to form channels that are filled with 10-coordinate Cs+ ions (Cs-S mean = 3.62(4) angstrom). Compound II crystallizes in the P2(1)/n space group (No. 14) with a = 5.885(2) angstrom, b = 14.413(2) angstrom, c = 11.079(2) angstrom, beta = 101.69(2)-degrees, V = 920 angstrom3, Z = 4, and d(calc) = 3.23g/CM3; number of data with F(o)2 > 3sigma(F(o)2) 1926, number of variables 74, 2theta(max)= 60-degrees. The final R/R(w) = 2.5/3.9. The structure consists of four-membered Sb2S2 rings linked along the a axis via pentasulfide ligands to form one-dimensional chains that are separated by Cs+ ions. The band gaps of the semiconducting I and II are 2.05 and 2.25 eV, respectively. Thermal analysis data for I and II are reported.