title: Ca3Sm3[Si9N17] and Ca3Yb3[Si9N17] nitridosilicates with interpenetrating nets that consist of star-shaped [N[4](SiN3)4] units and [Si5N16] supertetrahedra.
abstract: New nitridosilicates Ca(3)Sm(3)[Si(9)N(17)] and Ca(3)Yb(3)[Si(9)N(17)] were synthesized from the reactions of the pure metals (calcium and samarium/ytterbium) with silicon diimide "Si(NH)(2) " in a radio-frequency (rf) furnace at temperatures of up to 1650 °C. These isotypic compounds crystallize in the cubic space group P4(-)3m (no. 215) with lattice parameters a=739.50(3) pm; V=0.4044(1) nm(3); Z=1; wR(2) =0.029 (240 diffraction data, 26 parameters) for Ca(3)Sm(3)[Si(9)N(17)] and a=730.20(2) pm; V=0.3893(1) nm(3); wR(2) =0.039 (387 diffraction data, 27 parameters) for Ca(3)Yb(3)[Si(9)N(17)]. The new structure type of Ca(3)RE(3)[Si(9)N(17)] (RE=Sm, Yb) consists of two independent infinite networks, each of which have an expanded sphalerite (ZnS) topology in which the positions of the Zn and S atoms are replaced by voluminous [N([4])(SiN(3))(4)] units and [Si(5)N(16)] supertetrahedra, respectively, thereby displaying twofold interpenetration. As well, a structural description of Ca(3)Yb(3)[Si(9)N(17)], its thermal stability, and magnetic properties, as well as UV/Vis, IR, and Raman spectra, are presented.
authors: Institut für Allgemeine, Anorganische und Theoretische Chemie, Leopold-Franzens-Universität, Innsbruck, Austria.
authors: Hubert
authors: H
authors: Huppertz
authors: Oliver
authors: O
authors: Oeckler
authors: Alexandra
authors: A
authors: Lieb
authors: Robert
authors: R
authors: Glaum
authors: Dirk
authors: D
authors: Johrendt
authors: Marcus
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authors: Tegel
authors: Reinhard
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authors: Kaindl
authors: Wolfgang
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authors: Schnick