STRUCTURAL EVOLUTION FROM TIN SULFIDE (SELENIDE) LAYERED STRUCTURES TO NOVEL 3-CONNECTED AND 4-CONNECTED TIN OXY-SULFIDES

Addition of triethylenetetramine (TETN) and tetramethylammonium (TMA(+)) to SnS2 and SnSe2 slurries followed by heating at 150 degrees C under autogenous hydrothermal conditions results in novel thio and thio-oxide phases. These materials crystallize in time sequence as the added amines decompose. Initially 2-D frameworks with composition (Sn(3)X(7))(2-), X = S or Se are produced. In the case of the sulfides these are shown to transform to 2-D and 3-D oxy-sulfides frameworks which incorporate the decomposed template. The structures of two materials in this sequence have been determined from single crystal X-ray diffraction. The first, Sn3Se7 . C6N4H16CO, designated TETN-SnSe-1, crystallizes after 1 day of digestion in space group Pbca, with a = 23.553(6), b = 14.004(6), and c = 13.967(4) Angstrom. The structure contains SnSe5 coordination polyhedra which form Sn3Se44+ semicubes; six such semicubes are linked via Se-2 bridges to form apertures in the Sn3Se72- sheet in (010). Similar structures occur in the TETN-SnS and TMA-SnS systems. The second material, with a framework designated SnOS-SB3, is formed after 5 days of digestion in either the TMA-SnS or TETN-SnS systems and crystallizes in C2/c, with a = 35.62(1), b = 18.468(4), c = 21.858(6) Angstrom, and beta = 115.36(1)degrees. The structure consists of tetrahedral clusters of composition [Sn10S20O4](8-), which are linked via single S bridges at three corners to form a 2-D framework of composition [Sn20S37O8](10-). This is one member of a theoretical structural family with composition [Sn10S20-n/2O4](8-n-),where 0 less than or equal to n less than or equal to 4 and represents the number of connections between clusters. (C) 1995 Academic Press, Inc.