Low dimensional materials: Syntheses, structures, and optical properties of Rb2CuTaS4, Rb2CuTaSe4, RbCu2TaSe4, K3Ag3Ta2Se8, and Rb3AgTa2Se12

摘要

The new compounds Rb2CuTaS4 (1), Rb2CuTaSe4 (2), RbCu2TaSe4 (3), K3Ag3Ta2Se8 (4), and Rb3AgTa2Se12 (5) have been synthesized by the reactive flux method at 773 or 873 K. Their crystal structures were determined by single crystal X-ray diffraction. Crystal data for 1: space group Fddd, a = 5.598(1), b = 13.512(4), c = 23.854(5) Angstrom, Z = 8; Crystal data for 2: space group Fddd, a = 5.782(1), b = 13.924(3), c = 24.653(5) Angstrom, Z = 8; Crystal data for 3: space group C2cm, a = 5.7218(3), b = 19.2463(13), c = 7.7456(5) Angstrom, Z = 4; Crystal data for 4: space group C2/c, a = 25.1374(19), b = 6.1007(3), c = 14.4030(11) Angstrom, beta = 119.703(8), Z = 4; Crystal data for 5: space group P2(1), a = 9.8186(6), b = 13.7462(11), c = 15.7368(9) Angstrom, beta = 96.681(7)degrees, Z = 4. The compounds 1 and 2 are built up of (1)(infinity)[CuTaQ(4)](2-) anionic chains which are formed by edge-sharing CuQ(4) and TaQ(4) tetrahedra. The rubidium cations are located between the chains. Compound 3 consists of (2)(infinity)[Cu2TaSe4](-) anionic layers separated by rubidium cations. The anionic layers are formed by (1)(infinity)[CuTaSe4](2-) chains which are connected by CuSe4 tetrahedra that share common edges with the TaSe4 tetrahedra of neighboring chains. In compound 4(infinity)(1)[Ag3Ta2Se8](3-) anionic chains are found which are separated by potassium cations. These chains are formed by successive corner sharing of AgSe4 tetrahedra and edge sharing between AgSe4 and TaSe4 tetrahedra. All three structures are closely related with the sulvanite (Cu3VS4) structure type. Compound 5 contains a one dimensional (1)(infinity)[AgTa2Se12](3-) anionic chain formed by interconnection of AgSe4 tetrahedra and [Ta2Se11] units. In the structure three monoselenide, three diselenide, and one triselenide anions are found. Raman and far-IR spectroscopic data of compounds 1 and 4 were collected and an interpretation is presented.