Yb6Ir5Ga7 – A MgZn2 Superstructure

The gallide Yb₆Ir₅Ga₇ was synthesized by high‐frequency melting of the elements in a sealed niobium ampoule. The structure was refined from single‐crystal X‐ray diffractometer data: Nb_6.4Ir₄Al_7.6 type, P6₃/mcm, a = 930.4(1), c = 843.0(1) pm, wR₂ = 0.0597, 379 F² values and 22 variables. Yb₆Ir₅Ga₇ adopts a superstructure of the MgZn₂ Laves phase by a complete ordering of the iridium and gallium atoms on the zinc substructure, i.e. the network consists of ordered and condensed Ir₃Ga and IrGa₃ tetrahedra with Ir–Ga distances ranging from 260 to 265 pm. The crystal chemical details and the underlying group‐subgroup scheme are discussed.     

Rare Earth Ruthenium Gallides with the Ideal Composition Ln2Ru3Ga5 (Ln = La–Nd,Sm) crystallizing with U2Mn3Si5 (Sc2Fe3Si5) Type Structure

The rare earth ruthenium gallides Ln₂Ru₃Ga₅ (Ln = La, Ce, Pr, Nd, Sm) were prepared by arc‐melting of cold‐pressed pellets of the elemental components. They crystallize with a tetragonal structure (P4/mnc, Z = 4) first reported for U₂Mn₃Si₅. The crystal structures of the cerium and samarium compounds were refined from single‐crystal X‐ray data, resulting in significant deviations from the ideal compositions: Ce₂Ru_2.31(1)Ga_5.69(1), a = 1135.10(8) pm, c = 580.58(6) pm, R_F = 0.022 for 742 structure factors; Sm₂Ru_2.73(2)Ga_5.27(2), a = 1132.95(9) pm, c = 562.71(6) pm, R_F = 0.026 for 566 structure factors and 32 variable parameters each. The deviations from the ideal compositions 2:3:5 are discussed. A mixed Ru/Ga occupancy occurs only for one atomic site. The displacement parameters are relatively large for atoms with mixed occupancy within their coordination shell and small for atoms with no neighboring sites of mixed occupancy. Chemical bonding is analyzed on the basis of interatomic distances. Ln–Ga bonding is stronger than Ln–Ru bonding. Ru–Ga bonding is strong and Ru–Ru bonding is weak. The Ga–Ga interactions are of similar strength as in elemental gallium.     

Two‐ and Three‐Dimensional [IrSi] Networks in the Silicides Sm3Ir2Si2, HoIrSi,and YbIrSi

New intermetallic rare earth iridium silicides Sm₃Ir₂Si₂, HoIrSi, and YbIrSi were synthesized by reaction of the elements in sealed tantalum tubes in a high‐frequency furnace. The compounds were investigated by X‐ray diffraction both on powders and single crystals. HoIrSi and YbIrSi crystallize in a TiNiSi type structure, space group Pnma: a = 677.1(1), b = 417.37(6), c = 745.1(1) pm, wR2 = 0.0930, 340 F² values for HoIrSi, and a = 667.2(2), b = 414.16(8), c = 742.8(2) pm, wR2 = 0.0370, 262 F² values for YbIrSi with 20 parameters for each refinement. The iridium and silicon atoms build a three‐dimensional [IrSi] network in which the holmium(ytterbium) atoms are located in distorted hexagonal channels. Short Ir–Si distances (246–256 pm in YbIrSi) are indicative for strong Ir–Si bonding. Sm₃Ir₂Si₂ crystallizes in a site occupancy variant of the W₃CoB₃ type: Cmcm, a = 409.69(2), b = 1059.32(7), c = 1327.53(8) pm, wR2 = 0.0995, 383 F² values and 27 variables. The Ir1, Ir2, and Si atoms occupy the Co, B2, and B1 positions of W₃CoB₃, leading to eight‐membered Ir₄Si₄ rings within the puckered two‐dimensional [IrSi] network. The Ir–Si distances range from 245 to 251 pm. The [IrSi] networks are separated by the samarium atoms. Chemical bonding in HoIrSi, YbIrSi, and Sm₃Ir₂Si₂ is briefly discussed.     

Gallium‐Indium Ordering in the Complex [Ni2Ga3In] Network of GdNi2Ga3In

Polycrystalline samples of the isotypic quaternary compounds RENi₂Ga₃In (RE = Y, Gd – Tm) were obtained by arc‐melting of the elements. Crystals of the gadolinium compound were found by slow cooling of an arc‐melted button of the initial composition “GdNiGa₃In”. All samples were characterized by powder X‐ray diffraction. The structure of GdNi₂Ga_2.89In_1.11 was refined from single‐crystal X‐ray diffractometer data: new type, Pnma, a = 2426.38(7), b = 418.17(2), c = 927.27(3) pm, wR₂ = 0.0430, 1610 F² values and 88 variables. Two of the six crystallographically independent gallium sites show a small degree of Ga/In mixing. The nickel atoms show tricapped trigonal prismatic coordination by gadolinium, gallium, and indium. Together, the nickel, gallium, and indium atoms build up a complex three‐dimensional [Ni₂Ga₃In]^δ– network, which leaves cages for the gadolinium atoms. The indium atoms form zigzag chains with In–In distances of 337 pm. The crystal chemical similarities of the polyhedral packing in the GdNi₂Ga₃In and La₄Pd₁₀In₂₁ structures are discussed.     

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.     

Präparation und röntgenographische Charakterisierung der Verbindungen Ca3M2Ga2 (M = Pd,Pt) und Ca3M2Ga3 (M = Rh,Ir)

Preparation and Crystal Structures of the Compounds Ca₃Pd₂Ga₂, Ca₃Pt₂Ga₂, Ca₃Rh₂Ga₃, and Ca₃Ir₂Ga₃ The new compounds Ca₃Pd₂Ga₂, Ca₃Pt₂Ga₂, Ca₃Rh₂Ga₃, and Ca₃Ir₂Ga₃ were prepared by heating appropriate mixtures of the elements under an Argon-atmosphere. The results of the structure analysis of single crystals by means of X-ray diffraction are given in the section “Inhaltsübersicht”. Ca₃Pd₂Ga₂ and Ca₃Pt₂Ga₂ are isotypic and form the Y₃Rh₂Si₂ type structure (Pbcm), where the platinium metals have a trigonal environment consisting of Ga-atoms. The isotypic compounds Ca₃Rh₂Ga₃ and Ca₃Ir₂Ga₃ (Pbcm) form a new type of structure, which is related to the Y₃Rh₂Si₂ type with a distorted tetrahedral surrounding of Ga-atoms for Rh (resp. Ir).     

Rare Earth Metal Ruthenium Gallides R2Ru3Ga9 with Y2Co3Ga9 Type Structure

The twelve isotypic intermetallic compounds R₂Ru₃Ga₉ with R = Y, La–Nd, Sm, Gd–Tm were prepared by arc‐melting of the elemental components. Their crystal structure was determined from single‐crystal X‐ray data of Dy₂Ru₃Ga₉: Cmcm, a = 1279.3(2) pm, b = 755.6(1) pm, c = 964.7(1) pm, Z = 4, R = 0.020 for 671 structure factors and 42 variable parameters. All atomic positions have within two standard deviations ideal occupancies (occupancy values vary between 98.8(5) and 101.2(6)%). The structure is briefly discussed, emphasizing its relation to other structures with a high content of gallium or aluminum.     

SrIr9In18 – A Structurally Complex Intermetallic Compound with Sr@Ir4In12, Ir@In8 and Ir@In9 Building Units

Single crystals of SrIr₉In₁₈ were obtained by induction melting of the elements in a glassy carbon crucible followed by annealing at 1070 K. SrIr₉In₁₈ was structurally characterized by X-ray powder and single crystal diffraction: P4 m2, a = 811.21(5), c = 854.49(5) pm, wR₂ = 0.0511, 1223 F² values, and 46 variables. The structure is of a new type. The basic building units are Ir@In₈ (distorted square-prismatic, square anti-prismatic and bicapped trigonal prismatic coordination) and Ir@In₉ (distorted trigonal prismatic coordination) polyhedra, which condense to a three-dimensional network, which leaves large cavities for the strontium cations, which are coordinated to four iridium and twelve indium atoms. The [Ir₉In₁₈]^2– polyanionic network is stabilized through Ir–In (267–290 pm) and In–In (302–354 pm) bonding.     

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.     

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.     

Complex Borides RERu4B4 (RE = Ce,Pr, Nd,Sm) – Bonding Peculiarities and Magnetic Properties

The rare earth borides RERu₄B₄ (RE = Ce, Pr, Nd, Sm) were synthesized from the elements by arc‐melting and their crystal structures were studied on the basis of X‐ray powder and single‐crystal diffraction: LuRu₄B₄ type, I4₁/acd, a = 747.47(8), c = 1506.4(3) pm, wR₂ = 0.0579, 362 F² values for CeRu₄B₄, a = 751.3(2), c = 1507.1(5) pm, wR₂ = 0.0724, 471 F² values for PrRu₄B₄, a = 751.0(2), c = 1506.9(6) pm, wR₂ = 0.0598, 384 F² values for NdRu₄B₄, and a = 749.1(1), c = 1506.0(3) pm, wR₂ = 0.0759, 413 F² values for SmRu₄B₄, with 18 variables per refinement. Striking structural motifs of the RERu₄B₄ structures are Ru₄ tetrahedra and B₂ dumbbells with Ru–Ru and B–B distances of 271 and 180 pm in CeRu₄B₄. The intermediate valence of cerium leads to shorter Ce–Ru distances of 292 pm. CeRu₄B₄ behaves like a Pauli paramagnet with a small room temperature susceptibility of 1.5 × 10^–4 emu · mol^–1. Chemical bonding analyses shows substantial Ru–B and B–B bonding within the [Ru₄B₄] substructure.     

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.     

Synthesis and Structure of the Intermetallic Lithium Stannides LiTSn4 (T = Ru,Rh, Ir) with Ordered PdGa5 Type Structure

LiRuSn₄, LiRhSn₄, and LiIrSn₄ were prepared by reaction of the elements in sealed tantalum ampoules at 1220 K. The tubes were subsequently annealed at 870 K for one week. The three stannides were investigated by X‐ray diffraction on powders and single crystals and the structures were refined from single crystal data: I4/mcm, a = 662.61(3), c = 1116.98(7) pm, wR2 = 0.0730, 283 F² values for LiRuSn₄, a = 658.73(5), c = 1136.4(1) pm, wR2 = 0.0532, 313 F² values for LiRhSn₄ and a = 657.34(5), c = 1130.4(1) pm, wR2 = 0.0343, 176 F² values for LiIrSn₄ with 11 variables for each refinement. LiRuSn₄, LiRhSn₄, and LiIrSn₄ crystallize with a ternary ordered variant of the PdGa₅ structure. The transition metal (T) atoms have a square antiprismatic tin environment and they form two‐dimensional [TSn₄] polyanions with relatively short Ru—Sn (279 pm), Rh—Sn (280 pm), and Ir—Sn (280 pm) distances. The lithium atoms connect the polyanionic [TSn₄] layers. They are located in square prismatic voids formed by tin atoms. The crystal chemistry and chemical bonding of these stannides is briefly discussed.     

Sr5[NbN4]N ‐ A Nitridoniobate(V) Nitride Containing Isolated [NbN4]7‐ Tetrahedra and Octahedral Chains 1(Sr4Sr2/2N7+)

Sr₅[NbN₄]N (transparent, red single crystals) was synthesized by reaction of Sr2N with Nb under nitrogen at ambient pressure and 1223 K. The crystal structure was solved and refined in the space group Pbcm (no. 57), Z = 4, with lattice constants a = 646.6(3) pm, b = 1792.5(9) pm, c = 729.8(4) pm, and R = 0.019, wR² = 0.034. The crystal structure contains both isolated tetrahedra [NbN₄]^7‐ as well as chains of corner sharing octahedra 1(Sr₄Sr_2/2N⁷⁺). Strontium is irregularly coordinated by nitrogen (CN = 4 ‐ 6, Sr‐N: 252.3(4) ‐ 340.8(3) pm); nitrogen is located in a distorted octahedral environment by strontium and niobium (Nb‐N: 194.5(4) ‐ 199.2(2) pm). By formal reduction of the structural building units to their centers a close structural relationship to both the NiAs and the CaSi type structure is evident.     

Crystal Structure Determination of Tetrabarium‐digalliumoxide,Ba4Ga2O7

Single crystals of a new barium oxogallate were obtained by growth from a melt at 1500 °C. The compound is monoclinic, with cell parameters a = 17.7447(10) Å, b = 10.6719(5) Å, c = 7.2828(5) Å, β = 98.962(7)°, V = 1362.3(2) ų. The diffraction pattern shows systematic absences corresponding to the space group P12₁/c1. The structure was solved by direct methods followed by Fourier syntheses, and refined using a single crystal diffraction data set (R1 = 0.032 for 2173 reflections with I > 2σ(I)). The chemical composition derived from structure solution is Ba₄Ga₂O₇, with a unit cell content of Z = 6. Main building units of the structure are GaO₄ tetrahedra sharing one oxygen atom to form Ga₂O₇ groups. The Ga–O–Ga bridging angle of one of the two symmetrically independent groups is linear by symmetry. The dimers are crosslinked by barium cations coordinated by six to eight oxygen ligands.     

Die Kristallstrukturen von Rh10Ga17 und Ir3Ga5

Zusammenfassung Die Kristallstrukturen von Rh₁₀Ga₁₇ und Ir₃Ga₅ werden bestimmt und mittels zweidimensionalerFourier-Synthesen verfeinert. Die beiden Verbindungen gehören zu einer Gruppe von TiSi₂-Abkömmlingen der allgemeinen Formel T _n B_2n-m (TB_2-x ). Die Gitterkonstanten betragen für Rh₁₀Ga₁₇ a=5,813;c=47,46 und für Ir₃Ga₅ a=5,823;c=14,20 Å.

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The crystal structures of Rh₁₀Ga₁₇ and Ir₃Ga₅ have been determined by means of two-dimensionalFourier syntheses. The crystal structure of the two compounds of the general formula T _n B_2n-m (TB_2-x ) can be derived from the TiSi₂-type. The lattice parameters were found to be: Rh₁₀Ga₁₇ a=5,813;c=47,46 and Ir₃Ga₅ a=5,823;c=14,20 Å.

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Mit 2 Abbildungen     

K3Ga2(PO4)3 and Na3Ga(PO4)2

The structures of tripotassium digallium tris(phosphate), K₃Ga₂(PO₄)₃, and trisodium gallium bis(phosphate), Na₃Ga(PO₄)₂, have different irregular one‐dimensional alkali ion‐containing channels along the a axis of the orthorhombic and triclinic unit cells, respectively. The anionic subsystems consist of vortex‐linked PO₄ tetrahedra and GaO₄ tetrahedra or GaO₅ trigonal bipyramids in the first and second structure, respectively.     

Ga8Ir4B – ein Gallium-Iridiumborid mit isolierten,annähernd quadratisch planaren Ir4B-Gruppen in einer vom CaF2-Typ abgeleiteten Struktur

Ga₈Ir₄B – a Gallium Iridium Boride with isolated, nearly square planar Ir₄B Groups in a Structure derived from the CaF₂ Type The new compound Ga₈Ir₄B (tetragonal, I4₁/acd, a = 853.69(2) pm, c = 2 105.69(6) pm, Z = 8, 614 reflections, 31 parameters, R = 0.034) was prepared by reaction of the elements at 1 100°C. The structure is derived from the CaF₂ type. It contains isolated Ir₄B groups with boron in an unusual, nearly square planar coordination.     

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.     

Synthesis,Single Crystal Growth and Crystal Structure of Ta7Cu10Ga34 – a 8 × 4 × 2 Super Structure of CsCl

Single crystals of Ta₇Cu₁₀Ga₃₄ were grown from the elements in a Cu/Ga melt. Ta₇Cu₁₀Ga₃₄ represents the first ternary compound of the system Ta/Cu/Ga. The crystal structure (Cmmm, oC102, Z = 2, a = 23.803(1), b = 12.2087(4), c = 5.7487(2) Å, 1291 refl. 78 parameters, R₁ = 0.037, wR₂ = 0.070). The crystal structure is characterized by rods of pentagonal prisms MGa₁₀, which are alternatingly occupied by Ta and Cu. Four of these rods are connected to columns running in direction (001). These columns are linked by cubic units TaGa₈, CuGa₈, and GaGa₈. According to the characteristic structural elements and the size of the unit cell Ta₇Cu₁₀Ga₃₄ represents a 8 × 4 × 2 super structure of CsCl or bcc. With respect to the underlying CsCl structure the formula can be written as [Ta₇Cu₁₀Ga₂□₁₃]Ga₃₂, i.e. a cubic primitive packing of 32 Ga atoms with Ta, Cu, and Ga in cubic voids and 13 vacancies. The pentagonal‐prismatic coordination of Ta and Cu can formally be obtained from the cubic primitive packing of Ga atoms by a 45° rotation of a part of the Ga₈ cubes. There is a close similarity to the binary compounds Ta₈Ga₄₁ and Ta_2–xGa_5+x. The first one is also related to a CsCl‐like structure, the latter one contains rods of pentagonal prisms, which form the same columns. There are also relations to the ternaries V₂Cu₃Ga₈ and V₁₁Cu₉Ga₄₆, whose cubic structures are more or less complex variants of CsCl.