X-ray crystal structure determination of the triclinic misfit layer compound (SnS)1.20TiS2

(SnS)1.20TiS2 is a misfit layer compound built of alternately double layers of SnS with distorted rocksalt-type structure and sandwiches of TiS2 slightly distorted compared with those of 1T-TiS2. For comparison with other misfit layer compounds the triclinic subsystems are described in centred unit cells: for the SnS part, a1 = 5.683(1) angstrom, b1 = 5.832(1) angstrom, c1 = 11.680(5) angstrom, alpha-1 = 95.85(3)-degrees, beta-1 = 94.78(3)-degrees, gamma-1 = 90.03(2)-degrees, the space group is C1BAR and Z = 4; for the TiS2 part, a2 = 3.412(1) angstrom, b2 = 5.835(1) angstrom, c2 = 23.289(3) angstrom, alpha-2 = 95.86(1)-degrees, beta-2 = 90.30(1)-degrees, gamma-2 = 90.01(1)-degrees, the space group is F1BAR and Z = 4. In real space, a1 and a2 as well as b1 and b2 are parallel while the c axes diverge. In reciprocal space both sublattices have the (b*, c*) plane in common. Refinements were performed of the SnS part using 1351 independent reflections (R(F) = 0.087) and of the TiS2 part using 714 reflections (R(F) = 0.080). Each Sn atom is coordinated to five S atoms of the SnS double layer with SnS distances of 2.610(3), 2.866(4), 2.873(4), 2.911(4) and 2.976(4) angstrom, and at larger distances to S of TiS2. The Ti-S distances of the distorted TiS6 octahedra with symmetry 1BAR are 2.417(2), 2.429(1) and 2.428(1) angstrom. Sn atoms are between rows of sulphur along a of S of TiS2. The structural relationship with other misfit layer compounds is discussed.