Synthesis and Structures of New Layered Ternary Manganese Tellurides: AMnTe2 (A = K, Rb, Cs), Na3Mn4Te6, and NaMn1.56Te2
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The synthesis and crystal structures of new ternary manganese tellurides, AMnTe2 (A = K, Rb, Cs), Na3Mn4Te6, and NaMn1.56Te2, are reported. These compounds are synthesized by solid-state reaction and cation exchange techniques in sealed Nb tubes. The single-crystal structures of AMnTe2 (A = K, Rb), Na3Mn4Te6, and NaMn1.56Te2 have been determined; KMnTe2: a = 4.5110(4) , c = 14.909(2) , I4m2 (No. 119, Z = 2); RbMnTe2: a = 4.539(1) , c = 15.055(2) , I4m2 (No. 119, Z = 2); Na3Mn4Te6: a = 8.274(4) , b = 14.083(6) , c = 7.608(6) = 91.97(4), C2/m (No. 12, Z = 2); NaMn1.56Te2: a = 4.4973(8) , c = 7.638(2) , P3m1 (No. 164, Z = 1). The fundamental building blocks of the title compounds are MnTe4 tetrahedra. AMnTe2 (A = K, Rb, Cs) are isostructural with TlFeS2, consisting of layers built up by four corner-shared MnTe4 tetrahedra. Manganese telluride layers in Na3Mn4Te6 consist of two hexagonal nets of Te atoms between which two-thirds of the tetrahedral interstices are filled with Mn atoms to form two 63 honeycomb nets. NaMn1.56Te2 adopts a defective CaAl2Si2 structure type, in which Mn atoms partially and randomly occupy 78% of tetrahedral sites. Temperature-dependent magnetic susceptibilities measurements show that AMnTe2 (A = K, Rb, Cs) exhibit Curie-Weiss paramagnetism, whereas Na3Mn4Te6 and NaMn1.56Te2 show paramagnetism with a weak dependence on temperature. 1999 American Chemical Society.
