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Schlagwörter:
Cerium; Praseodymium; Carbides; Halides; Cluster compounds
Zusammenfassung:
The new compounds Pr(8)(C(2))(4)Cl(5) (1), Pr(14)(C(2))(7)Cl(9) (2), Pr(22)(C(2))(11)Cl(14) (3), Ce(2)(C(2))Cl (4), La(2)(C(2)) Br (5), Ce(2)(C(2)) Br (6), Pr(2)(C(2)) Br (7), Ce(18)(C(2))(9)Cl(11) (8), and Ce(26)(C(2))(13)Cl(16) (9) were prepared by heating mixtures of LnX(3), Ln and carbon or in an alternatively way LnX(3), and "Ln(2)C(3-x)" in appropriate amounts for several days between 750 and 1200 degrees C. The crystal structures were investigated by X-ray powder analysis (5-7) and/or single crystal diffraction (1-4, 8, 9). Pr(8)(C(2))(4)Cl(5) crystallizes in space group P2(1)/c with the lattice parameters a = 7.6169(12), b = 16.689(2), c = 6.7688(2) angstrom, beta = 103.94(1)degrees, Pr(14)(C(2))(7)Cl(9) in Pc with a = 7.6134(15), b = 29.432(6), c = 6.7705(14) angstrom, beta = 104.00(3)degrees, Pr(22)(C(2))(11)Cl(14) in P2(1)/c with a = 7.612(2), b = 46.127(9), c = 6.761(1) angstrom, beta = 103.92(3)degrees, Ce(2)(C(2))(2)Cl in C2/c with a = 14.573(3), b = 4.129(1), c = 6.696(1) angstrom, beta = 101.37(3)degrees, La(2)(C(2))(2)Br in C2/c with a = 15.313(5), b = 4.193(2), c = 6.842(2) angstrom, beta = 100.53(3)degrees, Ce(2)(C(2))(2)Br in C2/c with a = 15.120(3), b = 4.179(1), c = 6.743(2) angstrom, beta = 101.09(3)degrees, Pr(2)(C(2))(2)Br in C2/c with a = 15.054(5), b = 4.139(1), c = 6.713(3) angstrom, beta = 101.08(3)degrees, Ce(18)(C(2))(9)Cl(11) in P (1) over bar with a = 6.7705(14), b = 7.6573(15), c = 18.980(4) angstrom, alpha = 88.90(3)degrees, beta = 80.32(3)degrees, gamma = 76.09(3)degrees, and Ce(26)(C(2))(13)Cl(16) in P2(1)/c with a = 7.6644(15), b = 54.249(11), c = 6.7956(14) angstrom, beta = 103.98(3)degrees The crystal structures are composed of Ln octahedra centered by C(2) dumb-bells. Such Ln(6)(C(2))-octahedra are condensed into chains which are joined into undulated sheets. In compounds 1-4 three and four up and down inclined ribbons alternate (4(+)4, 4(+)3 3(+)4, 4(+)4 3(+)4 4(+)3), in compounds 8 and 9 four and five (4(+)5, 5(+)4 4(+)5 4(+)4), and in compounds 4-7 one, one ribbons (1(+)1) are present. The Ln-(C(2))-Ln layers are separated by monolayers of X atoms.
