Ternary Rare Earth Rhodium Antimonides Ln6Rh30Sb19 with Ln = La–Nd,Sm, and Eu

The six title compounds were prepared by annealing cold‐pressed pellets consisting of stoichiometric mixtures of binary rare earth and rhodium antimonides with additional elemental rhodium in evacuated silica tubes. Their crystal structure was determined from four‐circle X‐ray diffractometer data of a Eu₆Rh₃₀Sb₁₉ single crystal, which was isolated from an arc‐melted sample annealed just below the melting temperature in a high‐frequency furnace. It is hexagonal: P6₃/m, a = 1693.2(2) pm, c = 408.11(4) pm, Z = 1. The least‐squares refinement resulted in a residual of R = 0.034 for 1259 structure factors and 62 variable parameters. The structure shows some disorder around the 6₃ axis but otherwise is very similar to the structures of Sc₆Co₃₀Si₁₉ and Yb₆Co₃₀P₁₉, but different from that of U₆Co₃₀Si₁₉. The plot of the cell volumes of the new series Ln₆Rh₃₀Sb₁₉ indicates the europium atoms in Eu₆Rh₃₀Sb₁₉ to be at least partially divalent.     

Rare‐Earth‐Rich Magnesium Compounds RE23Rh7Mg4 (RE = La,Ce, Pr,Nd, Sm,Gd) with Tetrahedral Mg4 Clusters

The rare earth‐rich compounds RE₂₃Rh₇Mg₄ (RE = La, Ce, Pr, Nd, Sm, Gd) were prepared by induction‐melting the elements in sealed tantalum tubes. The new compounds were characterized by X‐ray powder diffraction. They crystallize with the hexagonal Pr₂₃Ir₇Mg₄ type structure, space group P6₃mc. The structures of La₂₃Rh₇Mg₄ (a = 1019.1(1), c = 2303.7(4) pm, wR2 = 0.0827, 1979 F² values, 69 variables), Nd₂₃Rh₇Mg₄ (a = 995.4(2), c = 2242.3(5) pm, wR2 = 0.0592, 2555 F² values, 74 variables) and Gd₂₃Rh_6.86(5)Mg₄ (a = 980.5(2), c = 2205.9(5) pm, wR2 = 0.0390, 2083 F² values, 71 variables) were refined from single crystal X‐ray diffractometer data. The three crystallographically different rhodium atoms have trigonal prismatic rare earth coordination with short RE–Rh distances (283–300 pm in Nd₂₃Rh₇Mg₄). The prisms are condensed via common edges, leading to a rigid three‐dimensional network in which isolated Mg₄ tetrahedra (312–317 pm Mg–Mg in Nd₂₃Rh₇Mg₄) are embedded. Temperature dependent magnetic susceptibility data of Ce₂₃Rh₇Mg₄ indicate Curie‐Weiss behavior with an experimental magnetic moment of 2.52(1) μ_B/Ce atom, indicative for stable trivalent cerium. Antiferromagnetic ordering is evident at 2.9 K.     

Lanthanoid Antimonides Ln2Sb5 (Ln = Sm,Gd, Tb,Dy) and Rationalization of Chemical Bonding within the Antimony Polyanion by Combining the Zintl‐Klemm Concept with Bond‐Length Bond‐Strength Relationships

The title compounds are formed by peritectic reactions. Single crystals could be isolated from samples with high antimony content. Their structure was determined for Dy₂Sb₅ from four‐circle X‐ray diffractometer data: P2₁/m, a = 1306.6(1) pm, b = 416.27(4) pm, c = 1458.4(1) pm, β = 102.213(8)°, Z = 4, R = 0.061 for 2980 structure factors and 86 variable parameters. All dysprosium atoms have nine antimony neighbors forming tricapped trigonal prisms with Dy–Sb distances varying between 308 and 338 pm. The antimony atoms occupy ten different sites with greatly varying coordination. One extreme case is an antimony atom surrounded only by dysprosium atoms in trigonal prismatic arrangement, the other one is an antimony atom in distorted octahedral antimony coordination. The various antimony‐antimony interactions (with Sb–Sb distances varying between 284 and 338 pm) are rationalized by combining the Zintl‐Klemm concept with bond‐length bond‐strength considerations.     

The Ternary Stannides MgRuSn4 and MgxRh3Sn7—x (x = 0.98—1.55)

The magnesium transition metal stannides MgRuSn₄ and Mg_xRh₃Sn_7—x (x = 0.98—1.55) were synthesized from the elements in glassy carbon crucibles in a water‐cooled sample chamber of a high‐frequency furnace. They were characterized by X‐ray diffraction on powders and single crystals. MgRuSn₄ adopts an ordered PdGa₅ type structure: I4/mcm, a = 674.7(1), c = 1118.1(2) pm, wR2 = 0.0506, 515 F² values and 12 variable parameters. The ruthenium atoms have a square‐antiprismatic tin coordination with Ru—Sn distances of 284 pm. These [RuSn_8/2] antiprisms are condensed via common faces forming two‐dimensional networks. The magnesium atoms fill square‐prismatic cavities between adjacent [RuSn₄] layers with Mg—Sn distances of 299 pm. The rhodium based stannides Mg_xRh₃Sn_7—x crystallize with the cubic Ir₃Ge₇ type structure, space groupe Im3m. The structures of four single crystals with x = 0.98, 1.17, 1.36, and 1.55 have been refined from X‐ray diffractometer data. With increasing tin substitution the a lattice parameter decreases from 932.3(1) pm for x = 0.98 to 929.49(6) pm for x = 1.55. The rhodium atoms have a square antiprismatic tin/magnesium coordination. Mixed Sn/Mg occupancies have been observed for both tin sites but to a larger extend for the 12d Sn2 site. Chemical bonding in MgRuSn₄ and Mg_xRh₃Sn_7—x is briefly discussed.     

Synthesis and Structures of Yb4Rh7Ge6 and Yb4Ir7Ge6

Larger single crystals of Yb₄Rh₇Ge₆ and Yb₄Ir₇Ge₆ were prepared from arc‐melted precursor alloys Rh₇Ge₆ and Ir₇Ge₆ and elemental ytterbium via the Bridgman method using tungsten crucibles. Yb₄Rh₇Ge₆ and Yb₄Ir₇Ge₆ were investigated by X‐ray diffraction on powders and single crystals. Both germanides crystallize with the cubic U₄Re₇Si₆ type structure, space group Im3m. Structure refinement from X‐ray single crystal diffractometer data yielded a = 825.3(1) pm, wR2 = 0.0292, 106 F² values, 10 variable parameters for Yb₄Rh₇Ge₆ and a = 826.6(2) pm, wR2 = 0.0486, 150 F² values, 10 variable parameters for Yb₄Ir₇Ge₆. The structures contain two crystallographically independent transition metal (T) atoms with octahedral (T1) and tetrahedral (T2) germanium coordination. The octahedra and tetrahedra are condensed via common corners and edges forming complex three‐dimensional [T₇Ge₆] networks in which the trivalent ytterbium atoms fill voids of coordination number 14.     

Preparation and Crystal Structures of Ternary Rare Earth Osmium Gallides LnOsGa3 (Ln = Gd—Tm) and LnOsGa3 (Ln = La—Nd)

The title compounds were prepared from the elemental components at high temperatures. The compounds LnOsGa₃ crystallize with the cubic TmRuGa₃ type structure which was refined from four‐circle X‐ray diffractometer data of TbOsGa₃: Pm3¯m, Z = 3, a = 640.8(1) pm, R = 0.014 for 173 structure factors and 10 variable parameters. The other gallides crystallize with a new structure type which was determined from single‐crystal X‐ray data of CeOsGa₄: Pmma, Z = 6, a = 963.9(2) pm, b = 880.1(1) pm, c = 767.0(1) pm, R = 0.030 for 744 F values and 56 variables. The structure may be considered as consisting of two kinds of alternating layers, although bonding within and between the layers is of similar strength. One kind of layers (A) is slightly puckered, two‐dimensionally infinite, hexagonal close packed, with the composition OsGa₃; the other kind of layers (B) is planar with the composition CeGa. The structure is closely related to that of Y₂Co₃Ga₉ where the corresponding layers have the compositions Co₃Ga₆ (A) and Y₂Ga₃ (B).     

Preparation and Crystal Structures of some Binary Pnictides of Scandium,Zirconium, and Hafnium: Sc5Bi3, ZrBi, α‐HfSb,HfBi, HfBi2, and the Compound Zr5Bi3X1–x,Possibly Stabilized by an Impurity (X)

The title compounds were prepared by reaction of the elemental components. Of these Sc₅Bi₃ is a new compound. Its orthorhombic β‐Yb₅Sb₃ type crystal structure was determined from single‐crystal X‐ray data: Pnma, a = 1124.4(1) pm, b = 888.6(1) pm, c = 777.2(1) pm, R = 0.024 for 1140 structure factors and 44 variable parameters. For the other compounds we have established the crystal structures. ZrBi has ZrSb type structure with a noticeable homogeneity range. This structure type was also found for the low temperature (α) form of HfSb and for HfBi. For α‐HfSb this structure was refined from single‐crystal X‐ray data: Cmcm, a = 377.07(4) pm, b = 1034.7(1) pm, c = 1388.7(1) pm, R = 0.043 for 432 F values and 22 variables. HfBi₂ has TiAs₂ type structure: Pnnm, a = 1014.2(2) pm, b = 1563.9(3) pm, c = 396.7(1) pm. The structure was refined from single‐crystal data to a residual of R = 0.074 for 1038 F values and 40 variables. In addition, a zirconium bismuthide, possibly stabilized by light impurity elements X and crystallizing with the hexagonal Mo₅Si₃C_1–x type structure, was observed: Zr₅Bi₃X_1–x, a = 873.51(6) pm, c = 599.08(5) pm. The positions of the heavy atoms of this structure were refined from X‐ray powder film data. Various aspects of impurity stabilization of intermetallics are discussed.     

Preparation and Crystal Structure of the Ternary Lanthanoid Platinum Antimonides Ln3Pt7Sb4 (Ln = Ce,Pr, Nd,and Sm) with Er3Pd7P4 Type Structure

The four compounds Ln₃Pt₇Sb₄ (Ln = Ce, Pr, Nd, and Sm) were prepared from the elements by arc‐melting and subsequent heat treatment in resistance and high‐frequency furnaces. The crystal structure of these isotypic compounds was determined from four‐circle X‐ray diffractometer data of Nd₃Pt₇Sb₄ [C2/m, a = 1644.0(2) pm, b = 429.3(1) pm, c = 1030.6(1) pm, β = 128.58(1)°, Z = 2, R = 0.032 for 698 structure factors and 46 variable parameters] and Sm₃Pt₇Sb₄ [a = 1639.5(2) pm, b = 427.1(1) pm, c = 1031.8(1) pm, β = 128.76(1)°, Z = 2, R = 0.025 for 816 F‐values and 46 variables]. The structure is isotypic with that of the homologous phosphide Er₃Pd₇P₄. In contrast to the structure of this phosphide, where the phosphorus atoms have the coordination number nine, the larger antimony atoms of Nd₃Pt₇Sb₄ obtain the coordination number ten. The structural relationships between the structures of EuNi_2—xSb₂, EuPd₂Sb₂, CeNi_2+xSb_2—x, Ce₃Pd₆Sb₅, and Nd₃Pt₇Sb₄, all closely related to the tetragonal BaAl₄ (ThCr₂Si₂) type structure, are briefly discussed emphasizing their space group relationships.     

Quaternary Germanides RE3TRh4Ge4 (RE = Ce,Pr, Nd; T = Nb,Ta) – A New Coloring Variant of the Aristotype AlB2

The quaternary germanides RE₃TRh₄Ge₄ (RE = Ce, Pr, Nd; T = Nb, Ta) were synthesized from the elements by arc‐melting and subsequent annealing in a muffle furnace. The structure of Ce₃TaRh₄Ge₄ was refined from single‐crystal X‐ray diffractometer data: new type, Pbam, a = 719.9(2), b = 1495.0(3), c = 431.61(8), wR₂ = 0.0678, 1004 F² values, and 40 variables. Isotypy of the remaining phases was evident from X‐ray powder patterns. Ce₃TaRh₄Ge₄ is a new superstructure variant of the aristotype AlB₂ with an ordering of cerium and tantalum on the aluminum site, whereas the honey‐comb network is built up by a 1:1 ordering of rhodium and germanium. This crystal‐chemical relationship is discussed based on a group‐subgroup scheme. The distinctly different size of tantalum and cerium leads to a pronounced puckering of the [Rh₄Ge₄] network, which shows the shortest interatomic distances (253–271 pm Rh–Ge) within the Ce₃TaRh₄Ge₄ structure. Another remarkable structural feature concerns the tantalum coordination with six shorter Ta–Rh bonds (265–266 pm) and six longer Ta–Ge bonds (294–295 pm). The [Rh₄Ge₄] network fully separates the tantalum and cerium atoms (Ce–Ce > 387 pm, Ta–Ta > 431 pm, and Ce–Ta > 359 pm). The electronic density of states DOS from DFT calculations show metallic behavior with large contributions of localized Ce 4f as well as itinerant ones from all constituents at the Fermi level but no significant magnetic polarization on Ce could be identified. The bonding characteristics described based on overlap populations illustrate further the crystal chemistry observations of the different coordination of Ce1 and Ce2 in Ce₃TaRh₄Ge₄. The Rh–Ge interactions within the network are highlighted as dominant. The bonding magnitudes follow the interatomic distances and identify differences of Ta bonding vs. Ce1/Ce2 bonding with the Rh and Ge substructures.     

Bi9Rh2Br3, Bi9Rh2I3 und Bi9Ir2I3 – Eine neue Strukturfamilie quasi‐eindimensionaler Metalle

Bi₉Rh₂Br₃, Bi₉Rh₂I₃, and Bi₉Ir₂I₃ – A New Structure Family of Quasi One‐dimensional Metals Bi₉Rh₂Br₃, Bi₉Rh₂I₃, and Bi₉Ir₂I₃ were synthesized from the elements using niobium bromides or iodides as auxiliaries to modify the partial pressures in the course of the reaction. X‐ray diffraction on single crystals showed that the compounds are not isomorphous. However they have a common structural principle: strands of condensed [MBi₈] polyhedra, which are separated by halide anions. The spatial arrangement of the [MBi_1/1Bi_7/2] strands differs with the combination of elements: In Bi₉Rh₂I₃ (monoclinic, P2₁/m (no. 11), a = 775.6(1), b = 1374.9(2), c = 901.1(2) pm, β = 109.29(2)°) all strands are oriented parallel to each other. Bi₉Rh₂Br₃ (monoclinic, P2₁/m (no. 11), a = 927.98(8), b = 1372.1(1), c = 1992.7(2) pm, β = 100.77(1)°) and Bi₉Ir₂I₃ (orthorhombic, Pnma (no. 62), a = 2677.5(5), b = 1394.2(2), c = 967.6(1) pm) are ordered polytypes with two orientations changing in alternating layers of characteristic widths. The experimental proof of metallic conductivity in Bi₉Ir₂I₃ supports the assumption of delocalised electrons inside the  [MBi_1/1Bi_7/2] strands. The magnetic susceptibility of Bi₉Rh₂Br₃ increases slowly with decreasing temperature and shows a local maximum at about 14 K.     

Das System Gd/Co/B: Darstellung und röntgenographische Charakterisierung von GdCo4B,Gd3Co11B4, GdCoB4 und GdCo12B6

The System Gd/Co/B: Preparation and Characterization by X‐ray Diffraction of GdCo₄B, Gd₃Co₁₁B₄, GdCoB₄, and GdCo₁₂B₆ The compounds GdCo₄B, Gd₃Co₁₁B₄, GdCoB₄, and GdCo₁₂B₆ were characterized by X‐ray investigations of single crystals. GdCo₄B (P 6/mmm, a = 505.9(1) pm, c = 690.1(1) pm) crystallizes with the CeCo₄B structure type; Gd₃Co₁₁B₄ (P 6/mmm, a = 508.7(1) pm, c = 982.9(9) pm) with the Ce₃Co₁₁B₄ stucture type; GdCo₁₂B₆ ( , a = 949.5(1) pm, c = 747.4(1) pm) with the SrNi₁₂B₆ structure type and GdCoB₄ (P bam, a = 591.3(9) pm, b = 1145.1(6) pm, c = 346.2(3) pm) with the YbCoB₄ structure type.     

Ein,altes‘ Rhodiumsulfid mit überraschender Struktur: Synthese,Kristallstruktur und elektronische Eigenschaften von Rh3S4

An ‘old' Rhodiumsulfide with surprising Structure – Synthesis, Crystal Structure, and Electronic Properties of Rh₃S₄ The reaction of rhodium with rhodium(III)‐chloride and sulfur at 1320 K in a sealed evacuated quartz glass ampoule yields silvery lustrous, air stable crystals of the rhodiumsulfide Rh₃S₄. Although a sulfide of this composition was described in 1935 a closer characterization has not been undertaken. Rh₃S₄ crystallizes in a new structure type in the monoclinic space group C2/m with a = 1029(2) pm, b = 1067(1) pm, c = 621.2(8) pm, β = 107.70(1)°. Besides strands of edge‐sharing RhS₆ octahedra which are connected by S₂ pairs (S–S = 220 pm), the crystal structure of Rh₃S₄ contains Rh₆ cluster rings in chair conformation with Rh–Rh single bond lengths of 270 pm. Both fragments are linked by common sulfur atoms. Extended Hückel calculations indicate bonding overlap for both S–S‐ and Rh–Rh‐interactions. Rh₃S₄ has a composition between the neighboring phases Rh₂S₃ and Rh₁₇S₁₅ and the structure combines typical fragments of both: RhS₆‐octahedra from Rh₂S₃ and domains of metal‐metal bonds as found in Rh₁₇S₁₅. Rh₃S₄ is a metallic conductor, down to 4.5 K the substance shows a weak, temperature independent paramagnetism.     

Zn11Rh18B8 and Zn10MRh18B8 with M = Sc,Ti, V,Cr, Mn,Fe, Co,Ni, Cu,Al, Si,Ge, Sn – New Ternary and Quaternary Zinc Rhodium Borides

Zn₁₁Rh₁₈B₈ and Zn₁₀MRh₁₈B₈ with M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Al, Si, Ge and Sn are obtained by reaction of the elemental components in sealed tantalum tubes at 1500 K. They crystallize tetragonally with Z = 2 in the spacegroup P4/mbm with lattice constants a = 1771.2(2) pm, c = 286.40(4) pm for Zn₁₁Rh₁₈B₈ and in the range a = 1767.65(9) pm, c = 285.96(3) pm (Zn₁₀NiRh₁₈B₈) to a = 1774.04(9) pm, c = 286.79(2) pm (Zn₁₀SnRh₁₈B₈) for the quaternary compounds. According to powder photographs all compounds are isotypic. Struture determinations based on single crystal X-ray data were performed with Zn₁₁Rh₁₈B₈, Zn₁₀FeRh₁₈B₈ and Zn₁₀NiRh₁₈B₈. The structure of Zn₁₁Rh₁₈B₈ is related to the Ti₃Co₅B₂ type. Along the short axis planar nets of rhodium atoms composed of triangles, squares, pentagons and elongated hexagons alternate with layers containing the boron and zinc atoms. The rhodium atoms form trigonal prisms centered by boron atoms, two kinds of tetragonal and pentagonal prisms centered by zinc atoms and elongated hexagonal prisms containing pairs of zinc atoms. In the quaternary compounds Zn₁₀MRh₁₈B₈ the zinc atoms in one sort of tetragonal prisms are replaced by M atoms.     

Synthese und Kristallstrukturen des Zink‐Rhodiumborids Zn5Rh8B4 und der Lithium‐ Magnesium‐Rhodiumboride LixMg5−xRh8B4 (x = 1.1 und 0.5) und Li8Mg4Rh19B12

Synthesis and Crystal Structures of Zinc Rhodium Boride Zn₅Rh₈B₄ and the Lithium Magnesium Rhodium Borides Li_xMg_5?xRh₈B₄ (x = 1.1 and 0.5) and Li₈Mg₄Rh₁₉B₁₂ The title compounds were prepared by reaction of the elemental components in metal ampoules under argon atmosphere (1100 °C, 7 d). In the case of Zn₅Rh₈B₄ (orthorhombic, space group Cmmm, a = 8.467(2) Å, b = 16.787(3) Å, c = 2.846(1) Å, Z = 2) a BN crucible enclosed in a sealed tantalum container was used. The syntheses of Li_xMg_5?xRh₈B₄ (orthorhombic, space group Cmmm, Z = 2, isotypic with Zn₅Rh₈B₄, lattice constants for x = 1.1: a = 8.511(3) Å, b = 16.588(6) Å, c = 2.885(1) Å, and for x = 0.5: a = 8.613(1) Å, b = 16.949(3) Å, c = 2.9139(2) Å) and Li₈Mg₄Rh₁₉B₁₂ (orthorhombic, space group Pbam, a = 26.210(5) Å, b = 13.612(4) Å, c = 2.8530(5) Å, Z = 2) were carried out in tantalum crucibles enclosed in steel containers using lithium as a metal flux. The crystal structures were solved from single crystal X‐ray diffraction data. In both structures Rh atoms reside at z = 0 and all non‐transition metal atoms at z = 1/2. Columns of Rh₆B trigonal prisms running along the c‐axis are laterally connected to form three‐dimensional networks with channels of various cross sections containing Li‐, Mg‐, and Zn‐atoms, respectively. A very short Li‐Li distance of 2.29(7) Å is observed in Li₈Mg₄Rh₁₉B₁₂.     

Zn5Ir7B3, Zn5Rh7B3 und Zn7+xRh9–xB3 (x ≈ 0,4) – neue ternäre Zink‐Platinmetallboride

Zn₅Ir₇B₃, Zn₅Rh₇B₃, and Zn_7+xRh_9–xB₃ (x ≈ 0.4) – New Ternary Zinc Platinum Metal Borides The new ternary zinc borides Zn₅Ir₇B₃, Zn₅Rh₇B₃, and Zn_7+xRh_9–xB₃ (x ≈ 0.4) were prepared by reaction of the elemental components at temperatures in the range 1200 to 1230 ?C. They crystallize orthorhombically in the space group Pmma with Z = 2. Zn₅Ir₇B₃ (a = 1116.1(2) pm, b = 284.96(4) pm, c = 1178.1(2) pm; R = 0.042, 1414 reflections, 47 parameters) and Zn₅Rh₇B₃ (a = 1101.6(2) pm, b = 283.94(3) pm, c = 1166.6(4) pm, R = 0.033, 787 reflections, 47 parameters) are isotypic. Along the short axis planar nets of platinum metal atoms at y = 0 alternate with layers containing the boron and zinc atoms at z = ¹/₂. By the stacking of the platinum metal nets columns of trigonal prisms centered by boron atoms, columns of pentagonal prisms containing zinc atoms and channels with horse shoe shaped cross sections, all running along the b‐axis are formed. The latter are filled by an aggregation of zinc atoms consisting of four parallel rows. In the structure of Zn_7+xRh_9–xB₃ (a = 1117.1(3) pm, b = 285.38(8) pm, c = 1484.8(5) pm; R = 0.026, 975 reflections, 59 parameters) one of the sitesets is occupied by Rh and Zn atoms approximately in the ratio 6 : 4. The structure contains the same building elements as those found in Zn₅Rh₇B₃ and in addition Rh prisms with elongated hexagon cross sections accommodating pairs of zinc atoms. These prisms are connected by common faces to form layers perpendicular to the c axis.     

Preparation and Crystal Structure of Rare Earth Rhenates: the Series Ln5Re2O12 with Ln = Y,Gd–Lu,and the Praseodymium Rhenates Pr3ReO8, Pr3Re2O10, and Pr4Re2O11

The crystal structure of the known compounds Ln₅Re₂O₁₂ (Ln = Y, Gd, Dy–Lu) and the new isotypic terbium rhenate Tb₅Re₂O₁₂ was determined from X‐ray data of a twinned crystal of Ho₅Re₂O₁₂: B2/m, a = 1236.5(4) pm, b = 748.2(2) pm, c = 563.8(1) pm, γ = 107.73(3)°, Z = 2, R = 0.034 for 379 structure factors and 37 variable parameters. The rhenium atoms (oxidation number +4.5) have octahedral oxygen coordination. These ReO₆ octahedra share edges, thus forming infinite strings with alternating short and long Re–Re distances: 243.6(2) and 320.1(2) pm. Of the three holmium positions two are surrounded by seven oxygen atoms and the third one has octahedral oxygen coordination. The crystal structure of Pr₃ReO₈ was refined from single‐crystal X‐ray data: P2₁/a, a = 1498.0(2) pm, b = 749.09(8) pm, c = 610.48(9) pm, γ = 110.39(1)°, R = 0.017 for 2082 F values and 110 variable parameters. It is isotypic with a structure first determined for Sm₃ReO₈. The new compounds Pr₃Re₂O₁₀ and Pr₄Re₂O₁₁ were prepared by reaction of elemental praseodymium with the metaperrhenate Pr(ReO₄)₃. They were characterized through their X‐ray powder diagrams. Pr₃Re₂O₁₀ was found to be monoclinic: a = 778.47(9) pm, b = 773.62(9) pm, c = 706.10(8) pm, β = 114.77(1)°. It is isotypic with La₃Os₂O₁₀ and La₃Re₂O₁₀. Pr₄Re₂O₁₁ crystallizes with Nd₄Re₂O₁₁ type structure with the tetragonal lattice constants a = 1272.49(3) pm, c = 562.29(2) pm. The compounds Nd₄Re₂O₁₁ and Sm₄Re₂O₁₁ are confirmed. The magnetic properties of Ho₅Re₂O₁₂, Tb₅Re₂O₁₂, Pr₃Re₂O₁₀, Pr₄Re₂O₁₁, Nd₄Re₂O₁₁, and Sm₄Re₂O₁₁ were investigated with a Faraday balance. None of these compounds shows magnetic order above 200 K.     

The Ternary Lanthanoid Nickel Arsenides Tb12Ni30As21 and Dy12Ni30As21 with (La,Ce)12Rh30P21 Type Related Structure

The title compounds were synthesized from the elements by reactions at high temperature. They crystallize with a hexagonal structure which was determined from single‐crystal X‐ray data of Dy₁₂Ni₃₀As₂₁: P6₃/m, Z = 1, a = 1698.5(5) pm, c = 387.7(1) pm, R = 0.053 for 797 F values and 69 variable parameters. It belongs to a large family of hexagonal structures with a metal to metalloid ratio of 2 : 1. In these hexagonal structures an ordered distribution of occupied atomic positions around the hexagonal 6₃ axis is possible only for refinements in space groups of lower symmetry. This is discussed for the present case and the very closely related structures reported for (La, Ce)₁₂Rh₃₀P₂₁ and Nd₃Ni₇P₅.     

New Ternary Alkaline Earth Metal Cerium(IV) Nitrides: CaCeN2 and SrCeN2

CaCeN₂ and SrCeN₂ were prepared by reactions of Li₂CeN₂ with Ca₃N₂ or Sr₂N in a nitrogen atmosphere at 1020 K. According to measurements of the magnetic susceptibilities both compounds contain Ce^IV. The crystal structures were determined by full‐profile Rietveld refinements of the X‐ray powder diffraction patterns. CaCeN₂ crystallizes in a rocksalt‐type structure with disordered Ca and Ce (space group Fm3¯m, a = 499.21(1) pm, R_profile = 0.061, R_Bragg = 0.034). The low temperature modification of SrCeN₂ crystallizes in the α‐NaFeO₂ type structure (space group R3¯m, a = 362.18(4) pm, c = 1795.8(2) pm, R_profile = 0.085, R_Bragg = 0.031). At elevated temperatures an order‐disorder phase transition leads to HT‐SrCeN₂ (space group Fm3¯m, a = 515.01(2) pm, quenched from 1273 K) with a cubic unit cell and complete disorder of Sr and Ce.     

Ternary Transition Metal Antimonides T5T' 1‐xSb2+x (T = Ti,Zr, Hf; T' = Fe,Co, Ni,Cu, Ru,Rh, Pd,Cd) with Nb5SiSn2 (Ordered W5Si3, Filled V4SiSb2) Type Structure

Fifteen new ternary antimonides T₅T' _1‐xSb_2+x were synthesized by reaction of the elemental components in an arc‐melting furnace. They crystallize with a tetragonal structure first reported for Nb₅SiSn₂ (space group I4/mcm, Z = 4.) A structure refinement from four‐circle X‐ray diffractometer data of Hf₅Fe_1‐xSb_2+x (a = 1086.0(1) pm, c = 550.1(1) pm, R = 0.033 for 270 structure factors and 18 variable parameters) showed deviations from the ideal occupancy for two atomic sites, resulting in the composition Hf_4.929(3)Fe_0.67(1)Sb_2.33(1). Structure refinements from X‐ray powder data resulted in the formula Ti₅Ni_0.45(2)Sb_2.55(2), while no deviation from the ideal composition was observed for Ti₅RhSb₂. The crystal structures of these compounds are discussed together with those of related binary and ternary compounds.     

Structure and Properties of EuZnGa

New ternary gallide EuZnGa was synthesized by reaction of the elements in a sealed tantalum tube at 1320 K and subsequent annealing at 970 K for seven days. EuZnGa was investigated by X‐ray diffraction on both powders and single crystals. Its structure was refined from single crystal diffractometer data: KHg₂ type, space group Imma, a = 461.7(2), b = 761.4(3), c = 777.0(3) pm, R = 0.041 for 486 structure factors and 13 variables. The zinc and gallium atoms statistically occupy the mercury position of the KHg₂ type of structure. No long‐range ordering between the zinc and gallium atoms could be detected from the X‐ray data. Magnetic susceptibility measurements show Curie‐Weiss behavior above 50 K with a magnetic moment of μ_exp = 7.86(5) μ_B/Eu and θ = 17(2) K, suggesting divalent europium. Low‐field, low‐temperature susceptibility measurements indicate cluster glass behavior (mictomagnetism) with a freezing temperature of 24(2) K. Magnetization measurements show a magnetic moment of 4.9(1) μ_B/Eu at 2 K and a magnetic flux density of 5.5 T. Electrical resistivity data indicate metallic behavior. ¹⁵¹Eu Mössbauer spectroscopic measurements show onset of magnetic hyperfine splitting at ≤ 17.0 K. Down to the temperature of 4.2 K the spectra reflect magnetic relaxation effects suggesting the presence of a substantial extent of disordering. This observation is consistent with the cluster glass behavior as evident from the magnetic susceptibility data and may be a consequence of the presence of multiple local Eu sites as expected from the statistical Zn and Ga distribution over the corresponding sites in the KHg₂ structure.