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1994 (1)
1992 (1)
1Author    Rainer Pöttgen, Wolfgang JeitschkoRequires cookie*
 Title    Sc5Re2C7, a Complex Carbide with C3-Units  
 Abstract    The title com pound was obtained by arc melting o f the elemental com ponents and subse­ quent annealing in a high frequency furnace. It crystallizes with the orthorhombic space group Cmmm, a = 779.26(7) pm, b = 1362.0(1) pm, c = 320.62(3) pm, V = 0.3403 nm3, Z -2. The structure was determined from single-crystal X-ray data and refined to a residual o f R = 0.021 (692 F values and 21 variables). It is closely related to the NaCl-structure. Three o f the seven carbon atom s per formula unit form linear C3-units with C -C bond lengths o f 134 pm. They are coordinated to ten Sc atom s forming bicapped quadratic prisms. Additional isolated C atoms are located in octahedral voids formed by four Sc and two Re atoms. Together with the Re atom s they form tw o-dim ensionally infinite [Re2C4"~]" polyanions. The Re atoms have highly distorted tetrahedral carbon coordination with R e -C bond lengths o f 200 and 208 pm corresponding to bond orders o f about two. This coordination seems to be compatible with the 18-electron rule. The near-neighbour coordination o f the Re atoms is assymmetric. It is suggested that this is due to the space requirements o f nonbonding electrons. Samples o f Sc5Re2C7 are sem iconducting and weakly paramagnetic. 
  Reference    Z. Naturforsch. 47b, 358 (1992); received September 2 1991 
  Published    1992 
  Keywords    Crystal Structure, Scandium Rhenium Carbide, 18-Electron Rule 
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 TEI-XML for    default:Reihe_B/47/ZNB-1992-47b-0358.pdf 
 Identifier    ZNB-1992-47b-0358 
 Volume    47 
2Author    Rainer Pöttgen, G. Ünter Block, Wolfgang Jeitschko, RonaldK. BehrensRequires cookie*
 Title    Preparation and Crystal Structure of the Carbides Ln12Re5C15 (Ln = Y, L a-N d, G d-E r)  
 Abstract    The title compounds were prepared by arc-melting of the elem ental components and sub­ sequent annealing. Their crystal structure is hexagonal P 6 2 m with one formula unit per cell. It was determined from single-crystal X-ray data o f La12R e5C i5 (a = 1116.8(1) pm. c = 545.3(1) pm. R = 0.060 for 287 structure factors and 27 variable parameters) and H o 12R e5C i5 (a = 1066.7(1) pm, c -504.2(1) pm, R = 0.018 for 392 F's and 31 variables). The structures correspond to the formula Ln12[ReC 3]2[R e3C3(C2)3], where the brackets indicate two differ­ ent trigonal planar anionic rhenium-carbon groups. The coordination of the rhenium atoms in these polyanions seem s to be compatible with the 18-electron rule. 
  Reference    Z. Naturforsch. 49b, 1081—1088 (1994); received February 22 1994 
  Published    1994 
  Keywords    Crystal Structure, Lanthanoid-Rhenium-Carbides, 18-Electron Rule 
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 TEI-XML for    default:Reihe_B/49/ZNB-1994-49b-1081.pdf 
 Identifier    ZNB-1994-49b-1081 
 Volume    49