Über einige Komplexboride mit Platinmetallen

Zusammenfassung Die Kristallstrukturen von W₂Ir₃B_6–x (x1) und von Mo₂IrB₂ werden mit Hilfe von Einkristalldaten bestimmt. Mo_2,5Ir_2,5B₅ ist mit der erstgenannten Kristallart isotyp, weist aber eine mehr statistische Verteilung der Metallatome auf. In Mo₂IrB₂ liegen B₄-Gruppen vor. (Cr,Ru)B und (Cr,Os)B kristallisieren im FeB-Typ; (Mo,Ru)B ist mit CrB und (Mo,Ru)₃B₄ mit Ta₃B₄ isotyp. Die strukturchemischen Bauprinzipien binärer und ternärer Boride werden im Bereich 40–60 At% B diskutiert.

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Complex borides with platinum metals

The crystal structures of W₂Ir₃B_6–x (x1) and Mo₂IrB₂ have been derived by means of single crystal photographs. Mo_2.5Ir_2.5B₅ is isotypic with W₂Ir₃B_6–x , displays a more statistical distribution, however, of the two kind of metal atoms. In Mo₂IrB₂ there are B₄-groups present. (Cr,Ru)B as well as (Cr,Os)B crystallize with FeB-type structure, (Mo,Ru)B with CrB-type structure and (Mo,Ru)₃B₄ is isotypic with Ta₃B₄. The principles of the structural chemistry of binary and ternary borides within the range of 40–60 at. % boron will be discussed.

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Mit 5 Abbildungen

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Herrn Prof. Dr. Dr. E. h.Otto Kratky zum 70. Geburtstag gewidmet.     

Neue AB2X2-Verbindungen mit CaBe2Ge2-Struktur

New AB₂X₂ Compounds with CaBe₂Ge₂ Structure Crystal structure of ternary RELi₂Sb₂ compounds (RE = Ce, Pr, Nd) is reported. The compounds are isotypic and crystallize tetragonally in the CaBe₂Ge₂ structure (space group P4/nmm), which is a modified type of the ThCr₂Si₂ structure.     

AlTaO4 mit AlNbO4-Struktur

AlTaO₄ with AlNbO₄ Structure Single crystals of AlTaO₄ were prepared by solid state reaction. It crystallizes with monoclinic symmetry, space group C–C2/m; a = 12.135, b = 3.776, c = 6.449 Å,β = 107.74°, Z = 4. AlTaO₄ exists in a second crystal form with AlNbO₄ structure.     

Ternäre Erdalkali-und Seltene Erd-Silicide und-Germanide mit AlB2-Struktur

Zusammenfassung Der AlB₂-Strukturtyp (C 32) wurde für SrGeZn, elf Verbindungen mit der ZusammensetzungRGe_1,33Cu_0,67 und vierzehn Silicide der FormelRSi_1,33Cu_0,67 aufgefunden, wobeiR ein Atom der Erdalkaligruppe oder der Seltenen Erdelemente symbolisiert. Das Auftreten von binären und ternären Vertretern dieses Strukturtyps wird in Beziehung gesetzt zu einem bestimmten Bereich der Valenzelektronenkonzentration.

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Ternary alkaline earth- and rare earth-silicides and-germanides with AlB₂-structure

The AlB₂ type structure was found with SrGeZn, eleven phases of compositionRGe_1,33Cu_0,67 and fourteen silicides of compositionRSi_1,33Cu_0,67 whereR indicates an alkaline earth or a rare earth element. The occurence of binary and ternary representatives of this structure type can be correlated with a certain range of valence electron concentration.

     

Ternäre Thallium-Übergangsmetall-Chalkogenide mit ThCr2Si2-Struktur

The existence of ternary chalcogenides of general composition TlT ₂ X ₂ (T=Fe,Co,Ni,X=S;T=Fe,Co,Ni,Cu,X=Se) crystallizing in the ThCr₂Si₂-structure type has been established. The crystal structure of TlCo₂S₂ was refined from single crystal diffractometer data. The dimensions of the tetragonal unit cells are: TlFe₂S₂;a=3.755 (1),c=13.35 (1) Å; TlCo₂S₂:a= =3.7410 (5),c=12.956(5) Å; TlNi₂S₂:a=3.792 (1),c=12.77 (1) Å; TlFe₂Se₂:a=3.890 (1),c=14.00(1) Å; TlCo₂Se₂:a=3.847 (1),c=13.54 (1) Å; TlNi₂Se₂:a=3.866 (1),c=13.41 (1) Å; TlCu₂Se₂:a=3.852 (1),c=14.01 (1) Å. These phases are the first chalcogenides found to crystallize in the ThCr₂Si₂-structure type. Unlike the already known representatives of this structure type they show a pronounced partial ionic character. Interatomic distances as well as the relations to the alkali thiometallates of Co and Mn are discussed.     

Ternäre Komplexboride mit ThMoB4-Typ

Ternary complex borides of formulaMM′B₄ ^* have been prepared within the system Th—{V, Mo, W, Re}—B. The crystal structure of these compounds has been determined by means of single crystal photographs of the compounds ThMoB₄ and ThWB₄. ThVB₄, ThMoB₄, ThWB₄, ThReB₄ were found to be isotypic. The relationship to the crystal chemistry of boron layer structures such as AlB₂, YCrB₄, and Y₂ReB₆ will be discussed.     

Ternäre Erdalkali-und Seltene Erdmetall-Silicide und-Germanide mit ThCr2Si2-Struktur

Zusammenfassung Es wurden 53 neue Verbindungen mit der ZusammensetzungRM ₂ B ₂ ^IV hergestellt, wobeiR ein Selten-Erdelement, Ca oder Sr bedeutet,M eines der Elemente: Cr, Fe, Co, Ni oder Cu ist undB ^IV entweder Si oder Ge bezeichnet. Alle Verbindungen kristallisieren im tetragonalen ThCr₂Si₂-(oder CeAl₂Ga₂-) Strukturtyp. Der letztere stellt eine geordnete ternäre Variante des BaAl₄-Typs dar, bei dem die zwei ungleichwertigen Al-Punktlagen mit verschiedenartigen Atomen besetzt sind.

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Ternary alkaline and rare earth silicides and germanides with ThCr₂Si₂ structure

Fifty three new compounds of compositionRM ₂ B ₂ ^IV were synthesized whereR is a rare earth element or Ca and Sr,M is Cr, Fe, Co, Ni or Cu andB ^IV either Si or Ge. All these compounds crystallize in the tetragonal ThCr₂Si₂ (or CeAl₂Ga₂) type which is an ordered ternary version of the BaAl₄ type, the two nonequivalent sites of the Al atoms being occupied by different kinds of atoms.

     

Einkristalle von CoNbO4 mit AlNbO4-Struktur

Single Crystals of CoNbO₄ with AlNbO₄ Structure The hitherto unknown single crystals of CoNbO₄ were prepared. CoNbO₄ has AlNbO₄ structure with monoclinic symmetry (space group C?C2/m; a = 1212.9; b = 374.9; c = 651.2 pm; β = 107.6°). X-ray investigations shows on ordered arrangement of Co³⁺ and Nb⁵⁺ with well defined differences in respect to oxocobaltates with Columbite type (CoNb₂O₆ = Co_0.33Nb_O.66O₂) and Rutil type (CoNbO₄ = Co_0.5-xNb_0.5+xO₂; 0 ? × ? 0.166) structure.     

Neue Boride mit Cr23C6-Struktur

Ohne Zusammenfassung     

Ternäre Thalliumchalkogenide mit Tl4Ge2S6-Struktur

The new ternary thallium chalcogenides Tl₄Si₂S₆, Tl₄Si₂Se₆, and Tl₄Ge₂Se₆ were synthetized from the elements. The compounds crystallize in the triclinic system (space group P ) with the cell parametersa=6.699 (5),b=6.645 (4),c=8.380 (5) Å, =90.32 (5), =112.00 (5), =112.32 (5)° for Tl₄Si₂S₆,a=6.875 (2),b=6.866 (2),c=8.731 (2) Å, =90.50 (2), =111.69 (2), =113.70 (2)° for Tl₄Si₂Se₆,a=6.925 (6),b=6.934 (7),c=8.771 (6) Å, =90.55 (7), =111.42 (6), =114.45 (7) for Tl₄Ge₂Se₆ andZ=1 for all cases. On the basis of single crystal X-ray intensity data the compounds were shown to be isostructural with Tl₄Ge₂S ₆ ¹ . The crystal structures of Tl₄Si₂S₆, Tl₄Si₂Se₆, and Tl₄Ge₂Se₆ are characterized by anions [Si₂S₆]^4–, [Si₂Se₆]^4–, and [Ge₂Se₆]^4– which consist of two tetrahedral SiS₄, SiSe₄, and GeSe₄ groups, respectively, with a common edge. A short comparative discussion of dinuclear tetrahedral thio- and selenoanions of main group elements is given.

     

Neue Verbindungen mit KCu4S3-Struktur

TlCu₄S₃, TlCu₄Se₃, KCu₄Se₃, RbCu₄Se₃, CsCu₄S₃ and CsCu₄Se₃ were prepared by direct synthesis or by the carbonate melt method. They are isotypic with KCu₄S₃, space group P4/mmm,Z=1. The lattice parameters are: TlCu₄S₃:a=3.894(1)Å,c=9.33(1)Å, TlCu₄Se₃:a=3.974(4)Å,c=9.84(2)Å, KCu₄Se₃:a=3.963(4)Å,c=9.81(3)Å, RbCu₄Se₃:a=4.048(2)Å,c=9.86(1)Å, CsCu₄S₃:a=3.964(3)Å,c=9.67(1)Å,and CsCu₄Se₃:a=4.091(2)Å,c=10.08(1)Å. The crystal structure of TlCu₄S₃ was refined from single crystal diffractometer data. Isotypy of the other compounds was checked by visual inspection of rotating crystal orDebye Scherrer film intensities. The relationship between the crystal structures of the MCu₄ X ₃-phases, the TlT₂ X ₂-phases (ThCr₂Si₂ type) and the anti-CaF₂ type is shown.

Hern Professor Dr.H. Bittner zum 60. Geburtstag in Verehrung gewidmet.     

Komplexboride mit Cr23C6-Typ (τ-Phasen)

Zusammenfassung Einige bei Komplexboriden beobachtete -Phasen werden hinsichtlich ihrer Ordnung charakterisiert.

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The ordering of some of the previously described complex borides (-phases) has been determined.

     

Über das kubische tantalmononitrid mit B 1-Struktur

Ohne Zusammenfassung

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The cubic tantalum mononitride with B 1 structure (short communication)

     

Uran-haltige Komplexboride

Ternary complex borides of formulaMM′B₄ have been prepared within the systems U-{V, Cr, Mo, W, Mn, Re, Fe, Co}-B. The phases U(Mo, W, Re)B₄ are isotypic with ThMoB₄-type structure; U(V, Cr, Mn, Fe, Co)B₄ crystallize with YCrB₄-type structure.     

Ternäre Verbindungen des Natriums und Kaliums mit CaCu4P2-Struktur

Ternary Compounds of Sodium and Potassium with CaCu₄P₂-type Structure NaCu₄As₂, NaCu₄Sb₂, KCu₄As₂, and KCu₄Sb₂ were prepared and investigated by single crystal methods. They crystallize rhombohedrally and are isotypic to CaCu₄P₂ (space group R3 m). The (hexagonal) lattice constants are By reaction of the same element compositions but alterated conditions six further compounds could be synthesized in the systems Na(K)/Cu(Ag)/P(As, Sb). They crystallize hexagonally, their structure which has not been determined seems to be related to the structure of CaCu₄P₂.     

Silicide und Germanide mit Gd6Cu8Ge8-Struktur

Zusammenfassung Die Verbindungen {Sc,Y,Tb,Dy,Ho,Er,Tm,Yb,Lu}₆Cu₈Si₈ sowie {Y,Yb}₆Cu₈Ge₈ werden hergestellt. Diese sind isotyp mit der Gd₆Cu₈Ge₈-Struktur. Die Gitterparameter werden ermittelt.

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Silicides and germanides with Gd₆Cu₈Ge₈-structure type

The compounds {Sc,Y,Tb,Dy,Ho,Er,Tm,Yb,Lu}₆Cu₈Si₈ and {Y,Yb}₆Cu₈Ge₈ have been prepared. They were found to be analogous with the Gd₆Cu₈Ge₈-structure type. The lattice parameters have been determined.

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Mit 1 Abbildung     

Über LaCo2P2 und andere Neue Verbindungen mit ThCr2Si2- und CaBe2Ge2-Struktur

On LaCo₂P₂ and Other New Compounds with ThCr₂Si₂- and CaBe₂Ge₂-Type Structure The compounds MCo₂P₂ (M = La, Ce, Pr, Nd, Sm, Th, U), MFe₂P₂ (M = La, Ce, U), and ThCo₂As₂ were prepared for the first time. Structure determinations from single crystal X-ray data of LaCo₂P₂ (R = 0.011; 325 F-values), CeCo₂P₂ (R = 0.023; 160 F), PrCo₂P₂ (R = 0.044; 441 F), LaFe₂P₂ (R = 0.024; 511 F), and CeFe₂P₂ (R = 0.016; 183 F) with 11 variable parameters each resulted in atomic positions within the range of the ThCr₂Si₂-type. The powder patterns of ThCo₂P₂, and ThCo₂As₂ show superstructure reflections indicating a CaBe₂Ge₂-type structure. The other compounds can be assigned to the ThCr₂Si₂-type. Chemical bonding of these can be rationalized by a simple band structure model where bonding transition metal – transition metal interactions are important.     

Ternäre Palladiumpnictide der Erdalkali- und Seltenen Erdmetalle mit ThCr2Si2- und CaBe2Ge2-Struktur

Fifteen compounds of compositionMPd₂ Pn ₂ (M = alkaline earth or rare earth metal,Pn = As, Sb, Bi) were prepared. TheirGuinier powder patterns show that the arsenides crystallize with the ThCr₂Si₂ type structure, the bismuthides with the closely related CaBe₂Ge₂ type structure. The antimonides most likely also have the CaBe₂Ge₂ structure as is demonstrated by a structure refinement of EuPd₂Sb₂ from single crystal X ray data (R = 0.039 for 366 independent structure factors and 15 variable parameters). The structure of SrPd₂As₂ (ThCr₂Si₂ type) was refined to a residual ofR = 0.020 for 182F values and 9 variables. EuPd₂Sb₂ is paramagnetic and a metallic conductor. A comparison of the cell volumes suggests intermediate valency for Eu in EuPd₂As₂.Chemical bonding and especially the reasons for the adoption of the ThCr₂Si₂ or CaBe₂Ge₂ type structures by these compounds are discussed. It is suggested that in going from the phosphides to the bismuthides the ThCr₂Si₂ structure is loosing and the CaBe₂Ge₂ structure is gaining stability due to decreasing Pd-Pd bonding and increasing Pd-pnictogen bonding. This trend is caused by the increasing size of the pnictogen component.

     

Neue Verbindungen mit SrNi2V2O8-Struktur: BaCo2V2O8 und BaMg2V2O8

New Compounds of the SrNi₂V₂O₈-Type: BaCo₂V₂O₈ and BaMg₂V₂O₈ For the first time BaCo₂V₂O₈ (A) and BaMg₂V₂O₈ (B) were prepared and investigated by X-ray methods. Space group: D–I4₁/acd, Z = 8. ((A): a = 12.4441, c = 8.4153 Å; (B): a = 12.4189, c = 8.4657 Å). A and B crystallize with higher symmetry, but they are isotypic with SrNi₂V₂O₈. The differences in crystal chemistry in respect to the BaNi₂V₂O₈-type are discussed.