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Research has been conducted on the transition-metal cluster complex. The use of the cyano group of this complex to bond to another transition-metal complex has been investigated and the results are reported.

Abstract: Single crystals of the new binaries CeTe1.90 and SmTe1.80 have been obtained. CeTe1.90 was synthesized at 1023K from the reaction of Ce, TeO2, and Te with the use of a CsCl flux. It crystallizes in the tetragonal space group P42 /n with 20 formula units in a cell of dimensions at 153K of , , . It is isostructural with the LnSe1.9 polyselenides (Ln=La, Ce, Pr) and with SmS1.90. SmTe1.80 was synthesized at 1223K from the reaction of Sm and Te in a KBr flux. SmTe1.80 crystallizes in a new structural type in the tetragonal space group P4/n with 20 formula units in a cell of dimensions at 153K of , , . Both of these layered structures, which may be derived from the ZrSiS structure type, consist of double layers of [LnTe] polyhedra separated by planar Te nets that contain vacancies. In these nets the shortest Te–Te distances are 2.9194(5), 3.1204(5), and 3.3324(6)Å in CeTe1.90 and 2.878(1), 2.9932(3), and 3.2114(7)Å in SmTe1.80. Neither a simple delineation of the Te–Te bonding nor an assignment of individual formal oxidation states is possible in either of these compounds if one takes strict account of the Te–Te distances. [Copyright &y& Elsevier]

Abstract: The quaternary oxychalcogenides Ln 4MnOSe6 (Ln=La, Ce, Nd), Ln 4FeOSe6 (Ln=La, Ce, Sm), and La4MnOS6 have been synthesized by the reactions of Ln (Ln=La, Ce, Nd, Sm), M (M=Mn, Fe), Se, and SeO2 at 1173K for the selenides or by the reaction of La2S3 and MnO at 1173K for the sulfide. Warning: These reactions frequently end in explosions. These isostructural compounds crystallize with two formula units in space group of the hexagonal system. The cell constants (a, c in Å) at 153K are: La4MnOSe6, 9.7596(3), 7.0722(4); La4FeOSe6, 9.7388(4), 7.0512(5); Ce4MnOSe6, 9.6795(4), 7.0235(5); Ce4FeOSe6, 9.6405(6), 6.9888(4); Nd4MnOSe6, 9.5553(5), 6.9516(5); Sm4FeOSe6, 9.4489(5), 6.8784(5); and La4MnOS6, 9.4766(6), 6.8246(6). The structure of these Ln 4 MOQ 6 compounds comprises a three-dimensional framework of interconnected LnOQ 7 bicapped trigonal prisms, MQ 6 octahedra, and the unusual LnOQ 6 tricapped tetrahedra. [Copyright &y& Elsevier]

The ternary selenides LnCuSe2 (Ln=La, Ce, Pr, Nd, Sm) have been synthesized by the reaction at 1173 K of Ln, Cu, and Se in a KBr or KI flux. The compounds, which are isostructural with LaCuS2, crystallize with four formula units in the space group P21/c of the monoclinic system. The structure may be thought of as consisting of layers of CuSe4 tetrahedra separated by double layers of LnSe7 monocapped trigonal prisms along the a-axis. Cell constants (A˚ or deg) at 153 K are: LaCuSe2, 6.8142(5), 7.5817(6), 7.2052(6), 97.573(1)°; CeCuSe2, 6.7630(5), 7.5311(6), 7.1650(6), 97.392(1)°; PrCuSe2, 6.740(1), 7.481(1), 7.141(1), 97.374(2)°; NdCuSe2, 6.7149(6), 7.4452(7), 7.1192(6), 97.310(1)°; SmCuSe2, 6.6655(6), 7.3825(7), 7.0724(6), 97.115(1)°. There are no Se–Se bonds in the structure of LnCuSe2; the formal oxidation states of Ln/Cu/Se are 3+/1+/2−. [Copyright &y& Elsevier]

The AnMnSe3 (An=Th, U) compounds were synthesized from high-temperature solid-state reactions of the constituent elements at 1223 and 1273 K, respectively. Both compounds are isostructural with UFeS3 and crystallize in the space group Cmcm of the orthorhombic system with four formula units in a cell. Cell constants (A˚) at 153 K are: ThMnSe3, 4.0304(4), 12.795(1), 9.2883(9); UMnSe3, 3.931(5), 12.705(14), 9.148(10). The structure comprises layers of MnSe6 octahedra that alternate with layers of AnSe8 bicapped trigonal prisms along the b-axis. Because there are no Se–Se bonds in the structure of AnMnSe3 the formal oxidation states of An/Mn/Se are 4+/2+/2−. UMnSe3 is a ferromagnet with TC=62 K. [Copyright &y& Elsevier]

The new quaternary selenide CeMn0.5OSe has been synthesized by the reaction of Ce, Mn, Se, and SeO2 at 1223 K. This compound crystallizes in space group P4/nmm of the tetragonal system with two formula units in a cell of dimensions at 153 K of a=4.0260(7) A˚, c=9.107(2) A˚. CeMn0.5OSe has the LaAgOS structure type. It is built from [CeO] fluorite-like layers where Ce4O tetrahedra share Ce–Ce edges that alternate with [MnSe] anti-fluorite like layers along [001]. An optical band gap of 2.01 eV has been derived from absorption measurements on the (100) crystal face of a CeMn0.5OSe single crystal. [Copyright &y& Elsevier]

The compounds CsGd2Cu3Se5 and CsTb2Cu3Se5 have been obtained through the reaction of CsCl, Gd2Se3 or Tb2Se3, and Cu2Se at 1123 K. These compounds crystallize in the RbSm2Ag3Se5 structure type with four formula units in the space group Cmcm of the orthorhombic system in cells of dimensions at 153 K of a=4.1417(3) A˚, b=14.6422(9) A˚, c=17.4543(11) A˚, V=1058.49(12) A˚3 for CsGd2Cu3Se5 and a=4.1268(4) A˚, b=14.6204(14) A˚, c=17.3390(16) A˚, V=1046.16(17) A˚3 for CsTb2Cu3Se5. This structure consists of ten-membered pentagonal rings in which the alkali-metal atoms are situated. The three-dimensional anionic framework is built from LnSe6 octahedra and CuSe4 tetrahedra. [Copyright &y& Elsevier]

An ordered polymorph of CuSm3Se6 crystallizes in the monoclinic space group P21/ m. The structure, which contains both monoselenide (Se2−) and diselenide (Se22−) units, comprises a three-dimensional network built from SmSe8 polyhedra and distorted CuSe4 tetrahedra. [ABSTRACT FROM AUTHOR]

Describes the crystal structure of the compound, dineodymium tritelluride, Nd[sub 2]Te[sub 3]. Crystallization in the U[sub 2S[sub 3] structure type; Presence of seven Te atoms; Description of the polyhedra; Presence of atoms on mirror planes.