SrPtIn,Sr2Pt3In4, and Ca2Au3In4 – Alkaline Earth Compounds with Complex Three-Dimensional [PtIn], [Pt3In4], and [Au3In4] Polyanions

Single phase SrPtIn, Sr₂Pt₃In₄ and Ca₂Au₃In₄ were prepared by high-frequency melting of the elements in water-cooled glassy carbon crucibles. X-ray diffraction of powders and single crystals yielded Pnma, oP12, a = 758.57(9) pm, b = 451.52(6) pm, c = 846.0(2) pm, wR2 = 0.0937, 467 F² values, 20 variables for SrPtIn, P62m, hP36, a = 1465.9(2) pm, c = 448.24(6) pm, wR2 = 0.0722, 1059 F² values, 44 variables for Sr₂Pt₃In₄ and Pnma, oP36, a = 1463.6(4) pm, b = 443.23(9) pm, c = 1272.3(2) pm, wR2 = 0.0694, 1344 F² values, 56 variables for Ca₂Au₃In₄. SrPtIn adopts the TiNiSi type structure. The indium atoms have a distorted tetrahedral platinum coordination. These InPt_4/4 tetrahedra are edge- and corner-shared, forming a three-dimensional [PtIn] polyanion in which the strontium atoms are embedded. Sr₂Pt₃In₄ crystallizes with the Hf₂Co₄P₃ type structure with the more electronegative platinum atoms occupying the phosphorus sites while the indium atoms are located on the cobalt positions. Ca₂Au₃In₄ is a new site occupancy variant of the YCo₅P₃ type. Gold atoms occupy the phosphorus sites and indium the cobalt sites, but one cobalt site is occupied by calcium atoms leading to the composition Ca₂Au₃In₄. Common geometrical motifs of both structures are condensed, platinum(gold)-centered trigonal prisms formed by the alkaline earth and indium atoms. The platinum (gold) and indium atoms form complex three-dimensional [Pt₃In₄] and [Au₃In₄] polyanions, respectively. The alkaline earth cations are located in distorted hexagonal tubes.     

Rare earth-nickel-indides Dy5Ni2In4 and RE4Ni11In20 (RE=Gd, Tb, Dy)

The new rare earth metal (RE)-nickel-indides Dy₅Ni₂In₄ and RE₄Ni₁₁In₂₀ (RE=Gd, Tb, Dy) were synthesized from the elements by arc-melting. Well-shaped single crystals were obtained by special annealing sequences. The four indides were investigated by X-ray diffraction on powders and single crystals: Lu₅Ni₂In₄ type, Pbam, Z=2, a=1784.2(8), b=787.7(3), c=359.9(1) pm, wR₂=0.0458, 891 F² values, 36 variables for Dy₅Ni₂In₄, U₄Ni₁₁Ga₂₀ type, C2/m, a=2254.0(9), b=433.8(3), c=1658.5(8) pm, β=124.59(2)°, wR₂=0.0794, 2154 F² values, 108 variables for Gd₄Ni₁₁In₂₀, a=2249.9(8), b=432.2(1), c=1657.9(5) pm, β=124.59(2)°, wR₂=0.0417, 2147 F² values, 108 variables for Tb₄Ni₁₁In₂₀, and a=2252.2(5), b=430.6(1), c=1659.7(5) pm, β=124.58(2)°, wR₂=0.0550, 2003 F² values, 109 variables for Dy₄Ni_10.80In_20.20. The 2d site in the dysprosium compound shows mixed Ni/In occupancy. Most nickel atoms in both series of compounds exhibit trigonal prismatic coordination by indium and rare earth atoms. Additionally, in the RE₄Ni₁₁In₂₀ compounds one observes one-dimensional nickel clusters (259 pm Ni₁-Ni₆ in Dy₄Ni_10.80In_20.20) that are embedded in an indium matrix. While only one short In₁-In₂ contact at 324 pm is observed in Dy₅Ni₂In₄, the more indium-rich Dy₄Ni_10.80In_20.20 structure exhibits a broader range in In-In interactions (291-364 pm). Together the nickel and indium atoms build up polyanionic networks, a two-dimensional one in Dy₅Ni₂In₄ and a complex three-dimensional network in Dy₄Ni_10.80In_20.20. These features have a clear consequence on the dysprosium coordination, i.e. a variety of short Dy-Dy contacts (338-379 pm) in Dy₅Ni₂In₄, while the dysprosium atoms are well separated (430 pm shortest Dy-Dy distance) within the distorted hexagonal channels of the [Ni_10.80In_20.20] polyanion of Dy₄Ni_10.80In_20.20. The crystal chemistry of both structure types is comparatively discussed.     

The Structure of La3Au4In7 and its Relation to the BaAl4 Type

La₃Au₄In₇ was prepared by arc‐melting of the elements and subsequent annealing at 970 K. X‐ray diffraction of powders and single crystals yielded I2/m11, mI28, a = 460.42(5) pm, b = 1389.5(1) pm, c = 1039.6(2) pm, α = 90.77(1)°, wR2 = 0.0621, 1089 F² values, 46 variables. The structure of La₃Au₄In₇ is of a new type. It may be considered as a monoclinically distorted, ordered variant of the La₃Al₁₁ type. The structural relation with the family of BaAl₄ related compounds is discussed on the basis of a group‐subgroup scheme. The gold and indium atoms in La₃Au₄In₇ build a three‐dimensional [Au₄In₇] polyanion in which the lanthanum atoms fill distorted pentagonal and hexagonal channels. Within the polyanion short Au–In and In–In distances are indicative of strongly bonding Au–In and In–In interactions.     

Syntheses and Structure of Gd3Rh1.940(7)In4

The gadolinium–rhodium–indide Gd₃Rh_1.940(7)In₄ was prepared by arc-melting of the elements and subsequent annealing in a corundum crucible in a sealed silica tube. Gd₃Rh_1.940(7)In₄ adopts the hexagonal Lu₃Co_1.87In₄ type, space group P[`6]P{\bar 6} , a = 781.4(5), c = 383.8(3) pm, wR2 = 0.0285, BASF = 0.375(1) (merohedric twinning via a twofold axis (xx0)), 648 F<sup>2</sup> values, 22 variables. The structure is derived from the well known ZrNiAl type through an ordering of rhodium and indium atoms on the Ni2 sites. The Rh/In ordering forces a reduction of the space group symmetry from P[`6]62mP{\bar 6}62m to P[`6]P{\bar 6} , leading to merohedric twinning for the investigated crystal. The Rh1 site has an occupancy of only 94.0(7)%. The investigated crystal had a composition Gd₃Rh_1.940(7)In₄. The main geometrical motif are three types of centered, tricapped trigonal prisms, i.e., [Rh1In2₆Gd₃], [Rh2Gd₆In2₃], and [In1Gd₆In2₃]. The shortest interatomic distances occur for Rh–In (276–296 pm) followed by In–In (297 pm). Together, the rhodium and indium atoms build up a three-dimensional [Rh_1.940(7)In₄] network, in which the gadolinium atoms fill slightly distorted pentagonal channels. The crystal chemistry of Gd₃Rh_1.940(7)In₄ is discussed on the basis of a group-subgroup scheme.     

New Indium‐Rich Compounds EuRhIn2 and EuRh2In8

EuRhIn₂ and EuRh₂In₈ were obtained by reacting the elements in sealed tantalum tubes in a high‐frequency furnace in a water‐cooled quartz glass sample chamber. Both indides were investigated by X‐ray powder and single crystal techniques: Cmcm, oC16, a = 432.2(1), b = 1058.8(1), c = 805.5(2) pm, wR2 = 0.0393, 471 F ² values, 16 variables for EuRhIn₂ and Pbam, oP44, a = 1611.8(2), b = 1381.7(2), c = 436.44(6) pm, wR2 = 0.0515, 1592 F ² values, 70 variables for EuRh₂In₈. EuRhIn₂ adopts the MgCuAl₂ type structure and may be considered as a rhodium filled variant of the binary Zintl phase EuIn₂. The indium substructure is homeotypic to the lonsdaleite type. Within the three‐dimensional [RhIn₂] polyanion the strongest bonding interactions occur for the Rh–In contacts followed by In–In. EuRh₂In₈ is the first indide with CaCo₂Al₈ type structure. The rhodium atoms have a trigonal prismatic indium coordination and the indium atoms form distorted indium centered InIn₈ cubes and InIn₁₀ pentagonal prisms with In–In distances ranging from 288 to 348 pm. Again, the rhodium and indium atoms together build a complex three‐dimensional [Rh₂In₈] polyanion in which the europium atoms are located within distorted pentagonal channels. Chemical bonding in EuRhIn₂ and EuRh₂In₈ is briefly discussed.     

Rare Earth-Rich Indides RE 5Pt2In4 ( RE = Sc, Y, La–Nd, Sm, Gd–Tm, Lu)

The isotypic indides RE ₅Pt₂In₄ (RE = Sc, Y, La–Nd, Sm, Gd–Tm, Lu) were synthesized by arc-melting of the elements and subsequent annealing. They were investigated via X-ray powder diffraction. Small single crystals of Gd₅Pt₂In₄ were grown via slow cooling and the structure was refined from X-ray single crystal diffractometer data: Pbam, a = 1819.2(9), b = 803.2(3), c = 367.6(2) pm, wR ² = 0.089, 893 F ² values and 36 parameters. The structure is an intergrowth variant of distorted trigonal and square prismatic slabs of compositions GdPt and GdIn. Together the platinum and indium atoms build up one-dimensional [Pt₂In₄] networks (292–333 pm Pt–In and 328–368 pm In–In) in an AA stacking sequence along the c axis. The gadolinium atoms fill distorted square and pentagonal prismatic cages between these networks with strong bonding to the platinum atoms.     

Gd3Pt4In12 and Tb3Pt4In12 — New Ternary Indides with Condensed Distorted [PtIn6] Trigonal Prisms

The ternary indium compounds Gd₃Pt₄In₁₂ and Tb₃Pt₄In₁₂ were synthesized from an indium flux. Arc‐melted precursor alloys with the starting compositions ∼GdPtIn₄ and ∼TbPtIn₄ were annealed with a slight excess of indium at 1200 K followed by slow cooling (5 K/h) to 870 K. Both compounds were investigated by X‐ray powder diffraction: a = 990.5(1), c = 1529.5(3) pm for Gd₃Pt₄In₁₂ and a = 988.65(9), c = 1524.0(1) pm for Tb₃Pt₄In₁₂. The structure of the gadolinium compound was solved and refined from single crystal X‐ray data: P3¯m1, wR2 = 0.0470, 1469 F² values and 62 variable parameters. Both crystallographically different platinum sites have a slightly distorted trigonal prismatic indium coordination. These [PtIn₆] prisms are condensed via common edges and corners forming a complex three‐dimensional [Pt₁₂In₃₂] network. The gadolinium, In1 and In7 atoms fill cavities within this polyanion. Tb₃Pt₄In₁₂ is isotypic with the gadolinium compound.     

Infinite Gold Zig‐Zag Chains as Structural Motif in Ca3Au3In – A Ternary Ordered Variant of the Ni4B3 Type

New auride Ca₃Au₃In was synthesized from the elements in a sealed tantalum tube in a high‐frequency furnace. Ca₃Au₃In was investigated by X‐ray powder and single crystal diffraction: ordered Ni₄B₃ type, Pnma, a = 1664.1(6), b = 457.3(2), c = 895.0(3) pm, wR2 = 0.0488, 1361 F² values, and 44 variables. The three crystallographically independent boron positions of the Ni₄B₃ type are occupied by the gold atoms, while the four nickel sites are occupied by calcium and indium in an ordered manner. All gold atoms have trigonal prismatic coordination, i.e. Ca₆ prisms for Au1 and Au2 and Ca₄In₂ prisms for Au3. While the Au3 atoms are isolated, we observe Au1–Au1 and Au2–Au2 zig‐zag chains at Au–Au distances of 292 and 284 pm. These slabs resemble the CrB type structure of CaAu. Consequently Ca₃Au₃In can be considered as a ternary auride. Together the Au2, Au3 and indium atoms build up a three‐dimensional [Au₂In] polyanionic network (281–293 pm Au–In) in which the chains of Au1 centered trigonal prisms are embedded. The crystal chemical similarities with the structures of Ni₄B₃, CaAuIn, and CaAu are discussed.     

Synthesis and structure of the scandium‐rich indides Sc5Ni2In4 and Sc5Rh2In4

The ternary indides Sc₅ Ni₂ In₄ and Sc₅ Rh₂ In₄ were synthesized by arc‐melting of the elements and subsequent annealing. A structural investigation by X‐ray powder and single crystal diffraction revealed: Lu₅ Ni₂ In₄ type, Pbam, a = 1716.3(2), b = 755.1(1), c = 335.22(5) pm, wR2 = 0.0721, 844 F² values for Sc₅ Ni₂ In₄, and a = 1754.3(3), b = 765.0(1), c = 332.97(6) pm, wR2 = 0.0363, 1107 F² values for Sc₅ Rh₂ In₄ with 36 variables per refinement. Both structures can be described as intergrowths of distorted AlB₂‐ and CsCl‐related slabs, where the transition metal (T) atoms have a trigonal prismatic and the indium atoms a distorted square prismatic coordination. The shortest interatomic distances occur for Sc T and T In. The crystal chemistry and chemical bonding in these intermetallics are briefly discussed. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:364–368, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20106     

Platinum‐Indium Polyanions in the Structures of LaPtIn4 and LnPtIn3 (Ln = La,Ce, Pr,Nd, Sm) and Structure Refinement of Ce2Pt2In

The title compounds were prepared by reacting the elements in an arc‐melting furnace and subsequent annealing. The LaRuSn₃ type structure of the new compounds LnPtIn₃ (Ln = La, Ce, Pr, Nd, Sm) was refined from single crystal X‐ray data for LaPtIn₃: Pm3n, a = 980.4(2) pm, wR2 = 0.0271, 399 F² values, 15 variables. Striking structural motifs of LaPtIn₃ are condensed distorted trigonal [PtIn₆] prisms with Pt–In distances of 269 pm. The lanthanum atoms occupy large cavities within the polyhedral network. Besides Pt–In bonding In–In bonding also plays an important role in LaPtIn₃ with In–In distances of 299 and 327 pm. The La1 position is occupied only to 91%, resulting in a composition La_0.98(1)PtIn₃. The La1 atoms show an extremely large displacement parameter indicating a rattling of these atoms in the In₁₂ cages. The so far most indium rich compound in the ternary system lanthanum‐platinum‐indium is LaPtIn₄ which was characterized on the basis of Guinier powder data: YNiAl₄‐type, Cmcm, a = 455.1(2) pm, b = 1687.5(5) pm, and c = 738.3(2) pm. The platinum atoms in LaPtIn₄ center trigonal prisms with the composition [La₂In₄]. Together with the indium atoms the platinum atoms form a complex three‐dimensional [PtIn₄] polyanion in which the lanthanum atoms occupy large hexagonal tubes. The structure of Ce₂Pt₂In is confirmed: Mo₂FeB₂‐type, P4/mbm, a = 779.8(1) pm, c = 388.5(1) pm, wR2 = 0.0466, 433 F² values, 12 parameters. It is built up from CsCl and AlB₂ related slabs with the compositions CeIn and CePt₂, respectively. Chemical bonding in the [PtIn₃] and [PtIn₄] polyanions of LaPtIn₃ and LaPtIn₄ is discussed.     

Synthesis, structure and properties of SrAu3In3 and EuAu3In3—New indides with gold zig-zag chains

New indides SrAu₃In₃ and EuAu₃In₃ were synthesized by induction melting of the elements in sealed tantalum tubes. Both indides were characterized by X-ray diffraction on powders and single crystals. They crystallize with a new orthorhombic structure type: Pmmn, Z=2, a=455.26(9), b=775.9(2), c=904.9(2) pm, wR2=0.0425, 485 F² values for SrAu₃In₃ and a=454.2(2), b=768.1(6), c=907.3(6) pm, wR2=0.0495, 551 F² values for EuAu₃In₃ with 26 variables for each refinement. The gold and indium atoms build up three-dimensional [Au₃In₃] polyanionic networks, which leave distorted hexagonal channels for the strontium and europium atoms. Within the networks one observes Au2 atoms without Au-Au contacts and gold zig-zag chains (279 pm Au1-Au1 in EuAu₃In₃). The Au-In and In-In distances in EuAu₃In₃ range from 270 to 290 and from 305 to 355 pm. The europium atoms within the distorted hexagonal channels have coordination number 14 (8 Au+6 In). EuAu₃In₃ shows Curie-Weiss behavior above 50 K with an experimental magnetic moment of 8.1(1) μB/Eu atom. ¹⁵¹Eu Mössbauer spectra show a single signal at δ=−11.31(1) mm/s, compatible with divalent europium. No magnetic ordering was detected down to 3 K.     

Synthesis and structures of YNiIn2 and Y4Ni11In20

Well-shaped single crystals of YNiIn₂ and Y₄Ni₁₁In₂₀ were obtained by arc-melting of the elements and subsequent slow cooling. Both indides were investigated by X-ray diffraction on powders and single crystals: MgCuAl₂ type, Cmcm, a=431.52(8), b=1042.0(2), c=730.0(1) pm, wR₂=0.0471, 587 F² values, 16 variables for YNiIn₂ and U₄Ni₁₁Ga₂₀ type, C2/m, a=2251.2(4), b=430.77(8), c=1658.5(3) pm, β=124.62(1)°, wR₂=0.0542, 1583 F² values, 108 variables for Y₄Ni₁₁In₂₀. Both structures are built up from three-dimensional [NiIn₂] and [Ni₁₁In₂₀] networks in which the yttrium atoms fill distorted pentagonal channels. The [NiIn₂] network has only Ni–In and In–In contacts, while also Ni–Ni bonding plays an important role in the [Ni₁₁In₂₀] network.     

Kationenverteilung und Überstrukturordnung in ternären und quaternären Sulfidspinellen MIIMS4 – Einkristallstrukturuntersuchungen

Cation Distribution and Superstructure Ordering in Ternary and Quaternary Sulfide Spinels M^IIM₂^III S₄ – Single Crystal Structure Determinations The crystal structures of spinel type MIn₂S₄ (M ? Mn, Co, Ni), MCr_2?2xIn_2xS₄ (M ? Mn, Ni), and Cd_0.52Co_0,48Cr₂S₄ were reinvestigated by X-ray methods using single crystals grown by vapour phase transport technique. The indium sulfides possess a partially inverse distribution of the metal ions on the tetrahedral (8a) and octahedral sites (16d) of the structure. The degrees of inversion λ are 0.34 (MnIn₂S₄, a = 1072.0(1) pm, structural parameter u = 0.25726(2)), 0.84 (CoIn₂S₄, a = 1058.1(1) pm, u = 0.26921(5)) und 0.93 (NiIn₂S₄ a = 1050.5(1), u = 0.26040(3)). In the case of the chromium indium sulfide solid solutions, the degrees of inversion (and the structural parameters) increase (and decrease) linearly with increase in indium content x. ψ-scans of reflections not allowed in the space group Fd3 m do not prove simultaneous diffraction. Refinement of the structure of MnIn₂S₄ in space group F4 3m results in a partial superstructure ordering of Mn and In on the tetrahedral sites, 4a Mn_0.83In_0.17, 4c Mn_0.49In_0.51. In the case of Cd_0.52Co_0.48Cr₂S₄, superstructure ordering is like Cd_0.41Co_0.59 and Cd_0.62Co_0.38, respectively.     

On the crystal chemistry of Tm2Ni1.896(4)In, Tm2.22(2)Ni1.81(1)In0.78(2), Tm4.83(3)Ni2In1.17(3), and Er5Ni2In

The rare earth-nickel-indides Tm₂Ni_1.896(4)In, Tm_2.22(2)Ni_1.81(1)In_0.78(2), Tm_4.83(3)Ni₂In_1.17(3), and Er₅Ni₂In were synthesized from the elements by arc-melting and subsequent annealing for the latter three compounds. Three indides were investigated by X-ray powder and single crystal diffraction: Mo₂FeB₂ type, P4/mbm, Z=2, a=731.08(4), c=358.80(3) pm, wR₂=0.0201, 178 F² values, 13 variables for Tm₂Ni_1.896(4)In, a=734.37(7), c=358.6(1) pm, wR₂=0.0539, 262 F² values, 14 variables for Tm_2.22(2)Ni_1.81(1)In_0.78(2), and Mo₅SiB₂ type, I4/mcm, a=751.0(2), c=1317.1(3) pm, wR₂=0.0751, 317 F² values, 17 variables for Tm_4.83(3)Ni₂In_1.17(3). X-ray powder data for Er₅Ni₂In revealed a=754.6(2) and c=1323.3(5) pm. The Mo₂FeB₂ type structures of Tm₂Ni_1.896(4)In and Tm_2.22(2)Ni_1.81(1)In_0.78(2) are intergrowths of slightly distorted CsCl and AlB₂ related slabs, however, with different crystal chemical features. The nickel sites within the AlB₂ slabs are not fully occupied in both indides. Additionally In/Tm mixing is possible at the center of the CsCl slab, as is evident from the structure refinement of Tm_2.22(2)Ni_1.81(1)In_0.78(2). The Mo₅SiB₂ type structures of Tm_4.83(3)Ni₂In_1.17(3) and Er₅Ni₂In can be considered as an intergrowth of distorted CuAl₂ and U₃Si₂ related slabs in an ABA′B′ stacking sequence along the c-axis. Again, one thulium site shows Tm/In mixing. The U₃Si₂ related slab has great structural similarities with the Mo₂FeB₂ type structure of Tm₂Ni_1.896(4)In and Tm_2.22(2)Ni_1.81(1)In_0.78(2). The crystal chemical peculiarities and chemical bonding in these intermetallics are briefly discussed.     

Rare Earth-Rich Indides <Emphasis Type="Italic">RE</Emphasis><Subscript>5</Subscript>Pt<Subscript>2</Subscript>In<Subscript>4</Subscript> (<Emphasis Type="Italic">RE</Emphasis> = Sc,Y, La–Nd,Sm, Gd–Tm,Lu)

Summary. The isotypic indides RE ₅Pt₂In₄ (RE = Sc, Y, La–Nd, Sm, Gd–Tm, Lu) were synthesized by arc-melting of the elements and subsequent annealing. They were investigated via X-ray powder diffraction. Small single crystals of Gd₅Pt₂In₄ were grown via slow cooling and the structure was refined from X-ray single crystal diffractometer data: Pbam, a = 1819.2(9), b = 803.2(3), c = 367.6(2) pm, wR ² = 0.089, 893 F ² values and 36 parameters. The structure is an intergrowth variant of distorted trigonal and square prismatic slabs of compositions GdPt and GdIn. Together the platinum and indium atoms build up one-dimensional [Pt₂In₄] networks (292–333 pm Pt–In and 328–368 pm In–In) in an AA stacking sequence along the c axis. The gadolinium atoms fill distorted square and pentagonal prismatic cages between these networks with strong bonding to the platinum atoms.     

Syntheses and Structures of RE4Pt10In21 (RE = La–Nd)

The isotypic indides RE₄Pt₁₀In₂₁ (RE = La, Ce, Pr, Nd) were prepared by melting mixtures of the elements in an arc‐furnace under an argon atmosphere. Single crystals were synthesized in tantalum ampoules using special temperature modes. The four samples were studied by powder and single crystal X‐ray diffraction: Ho₄Ni₁₀Ga₂₁ type, C2/m, a = 2305.8(2), b = 451.27(4), c = 1944.9(2) pm, β = 133.18(7)°, wR2 = 0.045, 2817 F² values, 107 variables for La₄Pt₁₀In₂₁, a = 2301.0(2), b = 448.76(4), c = 1941.6(2) pm, β = 133.050(8)°, wR2 = 0.056, 3099 F² values, 107 variables for Ce₄Pt₁₀In₂₁, a = 2297.4(2), b = 447.4(4), c = 1939.7(2) pm, β = 132.95(1)°, wR2 = 0.059, 3107 F² values, 107 variables for Pr₄Pt₁₀In₂₁, and a = 2294.7(4), b = 446.1(1), c = 1938.7(3) pm, β = 132.883(9)°, wR2 = 0.067, 2775 F² values, 107 variables for Nd₄Pt₁₀In₂₁. The 8j In2 positions of all structures have been refined with a split model. The In1 sites of the lanthanum and the cerium compound show small defects, leading to the refined composition La₄Pt₁₀In_20.966(6) and Ce₄Pt₁₀In_20.909(6) for the investigated crystals. The same position shows Pt/In mixing in the praseodymium and neodymium compound leading to the refined compositions Pr₄Pt_10.084(9)In_20.916(9) and Nd₄Pt_10.050(9)In_20.950(9). All platinum atoms have a tricapped trigonal prismatic coordination by rare‐earth metal and indium atoms. The shortest interatomic distances occur for Pt–In followed by In–In. Together, the platinum and indium atoms build up three‐dimensional [Pt₁₀In₂₁] networks in which the rare earth atoms fill distorted pentagonal tubes. The crystal chemistry of RE₄Pt₁₀In₂₁ is discussed and compared with the RE₄Pd₁₀In₂₁ indides and isotypic gallides.     

Syntheses and Structure of Gd<Subscript>3</Subscript>Rh<Subscript>1.940(7)</Subscript>In<Subscript>4</Subscript>

Summary. The gadolinium–rhodium–indide Gd₃Rh_1.940(7)In₄ was prepared by arc-melting of the elements and subsequent annealing in a corundum crucible in a sealed silica tube. Gd₃Rh_1.940(7)In₄ adopts the hexagonal Lu₃Co_1.87In₄ type, space group , a = 781.4(5), c = 383.8(3) pm, wR2 = 0.0285, BASF = 0.375(1) (merohedric twinning via a twofold axis (xx0)), 648 F² values, 22 variables. The structure is derived from the well known ZrNiAl type through an ordering of rhodium and indium atoms on the Ni2 sites. The Rh/In ordering forces a reduction of the space group symmetry from to , leading to merohedric twinning for the investigated crystal. The Rh1 site has an occupancy of only 94.0(7)%. The investigated crystal had a composition Gd₃Rh_1.940(7)In₄. The main geometrical motif are three types of centered, tricapped trigonal prisms, i.e., [Rh1In2₆Gd₃], [Rh2Gd₆In2₃], and [In1Gd₆In2₃]. The shortest interatomic distances occur for Rh–In (276–296 pm) followed by In–In (297 pm). Together, the rhodium and indium atoms build up a three-dimensional [Rh_1.940(7)In₄] network, in which the gadolinium atoms fill slightly distorted pentagonal channels. The crystal chemistry of Gd₃Rh_1.940(7)In₄ is discussed on the basis of a group-subgroup scheme.     

Rare earth metal-rich indides RE14Rh3−xIn3 (RE=Y, Dy, Ho, Er, Tm, Lu)

The rare earth (RE) metal-rich indides RE₁₄Rh_3-xIn₃ (RE=Y, Dy, Ho, Er, Tm, Lu) can be synthesized from the elements by arc-melting or induction melting in tantalum crucibles. They were investigated by X-ray diffraction on powders and single crystals: Lu₁₄Co₃In₃ type, space group P4₂/nmc, Z=4, a=961.7(1), c=2335.5(5) pm, wR2=0.052, 2047 F² values, 62 variables for Y₁₄Rh₃In₃, a=956.8(1), c=2322.5(5) pm, wR2=0.068, 1730 F² values, 63 variables for Dy₁₄Rh_2.89(1)In₃, a=952.4(1), c=2309.2(5) pm, wR2=0.041, 1706 F² values, 63 variables for Ho₁₄Rh_2.85(1)In₃, a=948.6(1), c=2302.8(5) pm, wR2=0.053, 1977 F² values, 63 variables for Er₁₄Rh_2.86(1)In₃, a=943.8(1), c=2291.5(5) pm, wR2=0.065, 1936 F² values, 63 variables for Tm₁₄Rh_2.89(1)In₃, and a=937.8(1), c=2276.5(5) pm, wR2=0.050, 1637 F² values, 63 variables for Lu₁₄Rh_2.74(1)In₃. Except Yb₁₄Rh₃In₃, the 8g Rh1 sites show small defects. Striking structural motifs are rhodium-centered trigonal prisms formed by the RE atoms with comparatively short Rh-RE distances (271-284 pm in Y₁₄Rh₃In₃). These prisms are condensed via common corners and edges building two-dimensional polyhedral units. Both crystallographically independent indium sites show distorted icosahedral coordination. The icosahedra around In2 are interpenetrating, leading to In2-In2 pairs (309 pm in Y₁₄Rh₃In₃).     

Complex three-dimensional platinum-indium networks in the ternary indides Dy2Pt7In16 and Tb6Pt12In23

Well crystallized samples of Dy₂Pt₇In₁₆ and Tb₆Pt₁₂In₂₃ were synthesized by an indium flux technique. Arc-melted precursor alloys with the starting compositions ∼DyPt₃In₆ and ∼TbPtIn₄ were annealed with a slight excess of indium at 1200 K followed by slow cooling (5 K/h) to 870 K. Both indides were investigated by X-ray diffraction on powders and single crystals: Cmmm, a=1211.1(2), b=1997.8(3), c=439.50(6) pm, wR2=0.0518, 1138 F² values, 45 variable parameters for Dy₂Pt₇In₁₆ and C2/ma=2834.6(4), b=440.05(7), c=1477.1(3) pm, β=112.37(1)°, wR2=0.0753, 2543 F² values, 126 variable parameters for Tb₆Pt₁₂In₂₃. The platinum atoms in the terbium compound have a distorted trigonal prismatic coordination. In Dy₂Pt₇In₁₆, trigonal and square prismatic coordination occur. The shortest interatomic distances are observed for Pt-In followed by In-In contacts. Considering these strong interactions, both structures can be described by complex three-dimensional [Pt₇In₁₆] and [Pt₁₂In₂₃] networks. The networks leave distorted pentagonal channels in Dy₂Pt₇In₁₆, while pentagonal and hexagonal channels occur in Tb₆Pt₁₂In₂₃. The crystal chemistry and chemical bonding of the two indides are briefly discussed.     

NixCo3-xO4表面修饰对CdSe/TiO2纳米管阵列光电化学氧化水活性的影响

利用氨挥发诱导法在CdSe/TiO2纳米管阵列表面负载一层NixCo3-xO4。采用SEM、XRD、XPS、UV-Vis对样品进行表征,通过线性扫描伏安法测定光阳极的释氧电势来评价其光电水氧化活性。结果表明:表面NixCo3-xO4是尖晶石结构;相对于CdSe/TiO2纳米管阵列光阳极,NixCo3-xO4/CdSe/TiO2光阳极能将光电氧化水的过电势降低430 mV。Ni离子的引入使得NixCo3-xO4表面富含三价阳离子(Ni3+,Co3+),从而促进CdSe/TiO2光阳极光电水氧化的进行。