The Nitrido Borates Ln3B2N4 (Ln = La–Nd) and La5B4N9: Syntheses,Structures, and Properties

Single crystals of the lanthanoide nitrido borates Ln₃B₂N₄ (Ln = La–Nd) and La₅B₄N₉ have been obtained from reactions of lanthanoide metal powder, lanthanoide nitride powder, and hexagonal boron nitride in calcium chloride melts. The isotypic compounds Ln₃B₂N₄ belong to the space group Immm (#71), Z = 2, with the lattice parameters for La₃B₂N₄: a = 362.94(3), b = 641.25(6), c = 1097.20(8) pm; Ce₃B₂N₄: a = 356.20(3), b = 631.90(6), c = 1071.91(8) pm; Pr₃B₂N₄: a = 353.46(4), b = 630.04(13), c = 1079.04(23) pm and Nd₃B₂N₄: a = 351.52(4), b = 627.01(15), c = 1075.59(23) pm. The structure of La₅B₄N₉ has been determined in the space group Pbcm (#57), Z = 4, with a = 988.25(5); b = 1263.48(7), c = 770.33(4) pm. These two structure types resemble three kinds of nitrido borate anions, the oxalate analogue B₂N₄ of Ln₃B₂N₄, and the carbonate analogue BN₃ together with the six‐membered ring system B₃N₆ of La₅(BN₃)(B₃N₆). In contrast to the valence compound La₅B₄N₉ the compounds (Ln³⁺)₃(B₂N₄)^8–(e^–) contain one electron in the conduction band, yielding temperature independent paramagnetism for La₃B₂N₄. The calculated electronic structure is developed through the formation of B₂N₄^8– ions by dimerisation of two BN₂ units.     

Synthese und Struktur der Nitridoborat‐Nitride Ln4(B2N4)N (Ln = La,Ce) des Formeltyps Ln3+x(B2N4)Nx (x = 0, 1, 2)

Synthesis and Structure of Nitridoborate Nitrides Ln₄(B₂N₄)N (Ln = La, Ce) of the Formula Type Ln_3+x(B₂N₄)N_x (x = 0, 1, 2) The missing member of the formula type Ln_3+x(B₂N₄)N_x with x = 1 was synthesized and characterized for Ln = La and Ce. According to the single‐crystal X‐ray structure solution Ce₄(B₂N₄)N crystallizes in the space group C2/m (Z = 2) with the lattice parameters a = 1238.2(1) pm, b = 357.32(3) pm, c = 905.21(7) pm and β = 129.700(1)°. The anisotropic structure refinement converged at R1 = 0.039 and wR2 = 0.099 for all independent reflections. A powder pattern of La₄(B₂N₄)N was indexed isotypically with a = 1260.4(1) pm, b = 366.15(3) pm, c = 919.8(1) pm and β = 129.727(6)°. A structure rational for nitridoborates and nitridoborate nitrides containing B₂N₄ ions with the general formula Ln_3+x(B₂N₄)N_x with x = 0, 1, 2 is presented.     

Anionische Fragmente aus h‐BN in der Struktur La6B4N10

Anionic Fragments of h‐BN in the Structure La₆B₄N₁₀ The compound La₆B₄N₁₀ was synthesized by solid state reactions at high temperatures. Crystals obtained for La₆B₄N₁₀ were systematically twinned and showed orthorhombic symmetry. An X‐ray crystal structure refinement on a needle shaped pseudo‐merohedral twin yielded the monoclinic space group P2₁/c, Z = 2, lattice parameters a = 971.89(6) pm, b = 1479.41(9) pm, c = 762.32(4) pm, β = 90.005(9)° and converged at R1 = 0.0352, wR2 = 0.0555 for all independent reflections. The structure of La₆(B₃N₆)(BN₃)N contains cyclic B₃N₆ ions with three exocyclic N atoms, carbonate ion like BN₃ units and nitride ions that can be considered as fragments or products of a nitration reaction of hexagonal boron nitride.     

Über das metallreiche Lanthannitridoboratnitrid La5(B2N4)N2

On the Metal‐rich Lanthanum Nitridoborate Nitride La₅(B₂N₄)N₂ La₅(B₂N₄)N₂ was synthesized by solid state reactions in fused tantalum containers from Li₃(BN₂), LaCl₃, Li₃N and La at 950 °C. The crystal structure refinement on a needle‐shaped single‐crystal yielded the monoclinic space group C2/m, the lattice parameters a = 1259.5(2), b = 368.53(4), c = 909.4(2) pm, β = 106.03(2)°, and R values of R1 = 0.041, wR2 = 0.066 for all independent reflections. The new compound La₅(B₂N₄)N₂ introduces the member with x = 2 to the formula type RE_3+x(B₂N₄)N_x (RE = rare earth, x = 0, 1). The structure contains the nitridoborate ion B₂N₄^8– that is isoelectronic with the oxalate ion and N^3–. Corresponding with (La³⁺)₅(B₂N₄)^8–(N^3–)₂(e^–) one additional electron is present.     

New Intermetallic Compounds Ln2Ni2Mg (Ln = Y,La–Nd,Sm, Gd–Tm) with Mo2FeB2 Structure

The title compounds were synthesized by reacting the elements in sealed tantalum tubes in a high‐frequency furnace. They crystallize with the Mo₂FeB₂ structure, a ternary ordered variant of the U₃Si₂ type, space group P4/mbm. All compounds were characterized through Guinier powder patterns and the lattice parameters were obtained from least‐squares fits. Four structures were refined from single crystal X‐ray data: a = 740.5(1) pm, c = 372.5(1) pm, wR2 = 0.0430, 247 F values, 13 variables for Y₂Ni_1.90Mg, a = 764.5(1) pm, c = 394.39(9) pm, wR2 = 0.0371, 310 F values, 12 variables for La₂Ni₂Mg, a = 754.4(1) pm, c = 385.20(9) pm, wR2 = 0.0460, 295 F values, 12 variables for Pr₂Ni₂Mg, and a = 752.53(8) pm, c = 382.33(5) pm, wR2 = 0.0183, 291 F values, and 12 variables for Nd₂Ni₂Mg. A refinement of the occupancy parameters indicated small defects on the nickel site of the yttrium compound, resulting in the composition Y₂Ni_1.90Mg for the investigated single crystal. The compounds with cerium, samarium, and gadolinium to thulium as rare earth component were characterized through their Guinier powder patterns. The cell colume of Ce₂Ni₂Mg is smaller than that of Pr₂Ni₂Mg, indicating intermediate‐valent cerium. The structures can be considered as an intergrowth of distored AlB₂ and CsCl related slabs of compositions LnNi₂ and LnMg. Chemical bonding in La₂Ni₂Mg and isotypic La₂Ni₂In is compared on the basis of extended Hückel calculations.     

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.     

Zur Kenntnis von Tripraseodym‐hexanitridotriborat Pr3B3N6: Neue Synthese und Verfeinerung der Kristallstruktur

On Tripraseodymium Hexanitridotriborate Pr₃B₃N₆: New Synthesis and Crystal Structure Refinement Single‐crystalline Pr₃B₃N₆ was obtained by the reaction of praseodymium and BN_x(NH)_y(NH₂)_z in a NaCl melt under N₂ atmosphere in a high‐frequency furnace at 1250 °C. Contrary to literature data, Pr₃B₃N₆ crystallizes in the centrosymmetric space group R 3 c as revealed by single‐crystal X‐ray diffraction (a = 1211.95(9), c = 701.53(7) pm, Z = 6, R1 = 0.0258, wR2 = 0.0658). In the solid, Pr₃B₃N₆ contains Pr³⁺ and planar cyclotrinitridoborate units B₃N₆^9–. The anions represent motifs from the structure of hexagonal boron nitride (h‐BN) and they are stacked analogously along [001]. Both the bond lengths B–N (average value 147.8 pm) and the interionic distances between the anions (350.8 pm) are comparable with the values in h‐BN.     

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.     

Phosphaniminato-Komplexe von Bor. Synthese und Kristallstrukturen von [BBr2(NPMe3)]2, [B2Br3(NPiPr3)2]Br, [B2(NPEt3)4]Br2, [B2Br2(NPPh3)3]BBr4 und [{B2(NMe2)2}2(NPEt3)2]Cl2

Phosphoraneiminato Complexes of Boron. Syntheses and Crystal Structures of [BBr₂(NPMe₃)]₂, [B₂Br₃(NPⁱPr₃)₂]Br, [B₂(NPEt₃)₄]Br₂, [B₂Br₂(NPPh₃)₃]BBr₄ and [{B₂(NMe₂)₂}₂(NPEt₃)₂]Cl The bromoderivatives of the title compounds are prepared from the corresponding silylated phosphoraneimines Me₃SiNPR₃ and boron tribromide. The boron subcompound [{B₂(NMe₂)₂}₂(NPEt₃)₂]Cl₂ derives from Me₃SiNPEt₃ and B₂Cl₂(NMe₂)₂. All complexes are characterized by NMR and IR spectroscopy as well as by crystal structure determinations. [BBr₂(NPMe₃)]₂ (1): Space group P2₁/n, Z = 2, R = 0.031. Lattice dimensions at ?50°C: a = 723.8, b = 894.2, c = 1305.4 pm, β = 92.35°. 1 forms centrosymmetric molecules in which the boron atoms are linked via μ₂-N bridges of the NPMe₃^? groups of from B₂N₂ four-membered rings with B? N distances of 149.9 and 150.9 pm. B₂Br₃(NPⁱPr₃)₂]Br (2): Space group P2₁, Z = 2, R = 0.059. Lattice dimensions at ?80°C: a = 817.6, b = 2198.7, c = 851.5 pm, β = 115.09°. In the cations of 2 the boron atoms are lined via the μ₂-N atoms of the NPⁱPr₃^? groups to form planar, asymmetric B₂N₂ four-membered rings with B? N distances of 143 and 156 pm. [B₂(NPEt₃)₄[Br₂·4CH₂Cl₂ (3): Space group C2/c, Z = 4, R = 0.042. Lattice dimensions at ?50°C: a = 1946.1, b = 1180.3, c = 2311.3 pm, β = 101.02°. The structure contains centrosymmetric dications in which both the boron atoms are lined by the N atoms of two of the NPEt₃^? groups to form a B₂N₂ four-membered ring with B? N distances of 149.6 pm. The remaining two NPEt₃^? groups are terminally bonded with very short B? N distances of 133.5 pm. B₂Br₂(NPPh₃)₃]BBr₄ (4): Space group P1 , Z = 2, R = 0.065. Lattice dimension at ?50°C: a = 1025.7, b = 1496.1, c = 1807.0 pm, α = 85.09°, β = 82.90°, γ = 82.72°. In the cation the boron atoms are lined via the μ₂-N atoms of two of the NPPh₃^? groups to form a nearly planer B₂N₂ four-membered ring with B? N distances of 149.3-153.1 pm. The third NPPh₃³ group is terminally connected with teh sp² hybridized boron atom and with a B? N distance of 134.1 pm along with an almost linear BNP bond angle of 173.6°. [{B₂(NMe₂)₂}₂(NPEt₂)₂]Cl₂ · 3CH₂Cl₂ (5): Space group C2/c, Z = 4, R = 0.098. Lattice dimensions at ?70°C: a = 1557.9, b = 1294.7, c = 2122.9 pm, β = 96.08°. The structure of 4 contains centrosymmetric dications in which two by two B-B dumb-bells are linked via the μ₂-N atoms of the two NEPt₃^? groups to form B₄N₂ six-membered rings with B? N distances of 150 and 156 pm and B-B distances of 173 pm. The B? N distances of the terminally bonded NMe₂^? groups correspond to 138 pm double bonds.     

Syntheses,Crystal Structure,and Properties of Hf2Ni2In,Hf2Ni2Sn,Hf2Cu2In,and Hf2Pd2In with Ordered Zr3Al2 Type Structure

Hf₂Ni₂In, Hf₂Ni₂Sn, Hf₂Cu₂In, and Hf₂Pd₂In were synthesized by reacting the elements in an arc-melting furnace under argon and subsequent annealing at 970 K. They crystallize with an ordered Zr₃Al₂ type structure, space group P4₂/mnm which was refined from single crystal X-ray data for Hf₂Ni₂In (a = 713.9(1) pm, c = 660.4(2) pm, wR2 = 0.0665, 513 F² values) and Hf₂Ni₂Sn (a = 703.1(1) pm, c = 676.1(2) pm, wR2 = 0.0423, 507 F² values) with 18 parameters for each refinement. The lattice constants for Hf₂Cu₂In and Hf₂Pd₂In are a = 715.5(1) pm, c = 677.0(1) pm and a = 742.6(1) pm, c = 679.4(2) pm, respectively. The structures may be considered as an intergrowth of distorted CsCl- and AlB₂-like slabs. Magnetic susceptibility measurements indicate Pauli paramagnetism for Hf₂Ni₂In and Hf₂Ni₂Sn, which is consistent with the metallic conductivity observed for Hf₂Ni₂In. ¹¹⁹Sn Mössbauer spectroscopy of Hf₂Ni₂Sn shows one signal with an isomer shift of δ = 1.59(1) mm/s subjected to quadrupole splitting of δE_q = 0.81(1) mm/s.     

La4N2S3: Ein neues Nitridsulfid des Lanthans mit beispielloser Kristallstruktur

La₄N₂S₃: A New Nitride Sulfide of Lanthanum with Unprecedented Crystal Structure The oxidation of lanthanum powder with sulfur and cesium azide (CsN₃) in the presence of lanthanum tribromide (LaBr₃) yields lanthanum nitride sulfide with the composition La₄N₂S₃ when appropriate molar ratios of the reactants are used. Additional cesium bromide (CsBr) as a flux secures fast reactions (7 d) at 900 °C in evacuated silica tubes as well as the formation of almost black single crystals. The orthorhombic crystal structure (Pnnm, Z = 2) was determined from single crystal X‐ray diffraction data (a = 641.98(4), b = 1581.42(9), c = 409.87(3) pm). Two crystallographically different La³⁺ cations are present, La1 resides in sixfold coordination of two N^3? and four S^2? anions forming a trigonal prism and La2 is coordinated by two N^3? and five S^2? in the shape of a monocapped trigonal prism. However, the main feature of the crystal structure comprises N^3?‐centred (La³⁺)₄ tetrahedra which arrange as pairs [N₂La₆]¹²⁺ of edge‐shared [NLa₄]⁹⁺ units and which are further connected via four vertices to form double chains . They get bundled along [001] like a hexagonal rod packing and are held together by two crystallographically different S^2? anions. Further motifs for the connectivity of [NM₄]⁹⁺ tetrahedra in crystal structures of nitride chalcogenides and halides of the rare‐earth elements (M = Sc, Y, La; Ce – Lu) with ratios of N : M = 1 : 2 are presented and discussed for comparison.     

La5Al3Ni2 – an Intermetallic Phase Observed upon Crystallization of La50Al25Ni25 Metallic Glass

The yet unknown intermetallic phase La₅Al₃Ni₂ was obtained by partially crystallizing amorphous La₅₀Al₂₅Ni₂₅ at 550 K (further heating above 600 K leads to irreversible disappearance of this phase), and its crystal structure was determined from X‐ray powder diffraction data. The crystal structure of the La₅Al₃Ni₂ phase constitutes a new structure type (Cmcm, a = 14.231Å, b = 6.914Å, c = 10.460Å, oC40) and is built from [Al₃Ni₂] chains surrounded by La atoms. In the ternary system La‐Al‐Ni La₅Al₃Ni₂ is located on the section La₅₀Al_50−nNi_n (0 ≤ n ≤ 50) with the binary compounds LaAl and LaNi as end members. Strikingly, also the crystal structures of the end members can be conceived as chain structures with Al and Ni chains surrounded by La, respectively.     

Darstellung,Kristallstruktur und magnetische Eigenschaften von In2Ni21B6

Preparation, Crystal Structure, and Magnetic Properties of In₂Ni₂₁B₆ In₂Ni₂₁B₆ was prepared by solid state reaction of the elements at 1223 K. The single‐crystals, obtained for the first time, exhibit metallic luster and crystallize in space group Fm 3 m (a = 1059.11(2) pm; Z = 4; 128 symmetry independent reflections; R1 = 0.027; wR2 = 0.125). In₂Ni₂₁B₆ is related to the Cr₂₃C₆‐structure and belongs to the structural family of τ‐borides. The compound melts at 1426 K. Polycrystalline samples of In₂Ni₂₁B₆ are ferromagnetic with a Curie‐Temperature of T_C = 596 K and show metallic conductivity in the range from 12 K to 320 K.     

Synthese und Kristallstruktur des ersten Oxonitridoborates — Sr3[B3O3N3]

Synthesis and Crystal Structure of the First Oxonitridoborate — Sr₃[B₃O₃N₃] The cyclotri(oxonitridoborate) Sr₃[B₃O₃N₃] was synthesized at 1450 °C as coarsely crystalline colourless crystals by the reaction of SrCO₃ with poly(boron amide imide) using a radiofrequency furnace. The structure was solved by single‐crystal X‐ray diffractometry (Sr₃[B₃O₃N₃], Z = 4, P2₁/n, a = 663.16(2), b = 786.06(2), c = 1175.90(3) pm, η = 92.393(1)°, R1= 0.0441, wR2 = 0.1075, 1081 independent reflections, 110 refined parameters). Besides Sr²⁺ there are hitherto unknown cyclic [B₃O₃N₃]^6— ions (B—N 143.7(10) — 149.1(9) pm, B—O 140.5(8) — 141.4(8) pm).     

Phosphanimin- und Phosphaniminato-Komplexe von Bor. Synthese und Kristallstrukturen von [BF3(Me3SiNPEt3)], [BCl2(NPPh3)]2, [BCl2(NPEt3)]2, [B2Cl3(NPEt3)2]+BCl4− und [B2Cl2(NPiPr3)3]+BCl4−

Phosphaneimine and Phosphoraneiminato Complexes of Boron. Synthesis and Crystal Structures of [BF₃(Me₃SiNPEt₃)], [BCl₂(NPPh₃)]₂, [BCl₂(NPEt₃)]₂, [B₂Cl₃(NPEt₃)₂]⁺BCl₄^?, and [B₂Cl₂(NPⁱPr₃)₃]⁺BCl₄^? The title compounds have been prepared from the corresponding silylated phosphaneimines and boron trifluoride etherate and boron trichloride, respectively. The compounds form white moisture sensitive crystals, which were characterized by ¹¹B-nmr-spectroscopy, IR-spectroscopy and by crystal structure determinations. [BF₃(Me₃SiNPEt₃)] : Space group P2₁/c, Z = 4, R = 0.032 for reflections with I > 2σ(I). Lattice dimensions at ?70°C: a = 1361.0, b = 819.56, c = 1422.5 pm, β = 109.86°. The donor acceptor complex forms monomeric molecules with a B? N bond length of 157.8 pm. [BCl₂(NPPh₃)]₂ · 2 CH₂Cl₂ : Space group P2₁/c, Z = 2, R = 0.049 for reflections with I > 2σ(I). Lattice dimensions at ?50°C: a = 1184.6, b = 2086.4, c = 843.0 pm, β = 96.86°. The compound forms centrosymmetric dimeric molecules in which the boron atoms are linked to B₂N₂ four-membered rings with B? N distances of 152.7 pm via μ₂-N bridges of the NPPh₃ groups. [BCl₂(NPEt₃)]₂ : Space group Pbca, Z = 4, R = 0.029 for reflections with I > 2σ(I). Lattice dimensions at ?90°C: a = 1269.5, b = 1138.7, c = 1470.3 pm. The compound has a molecular structure corresponding to the phenyl compound with B? N ring distances of 151.0 pm. [B₂Cl₃(NPEt₃)₂]⁺BCl₄^? : Space group Pbca, Z = 8, R = 0.034 for reflections with I > 2σ(I). Lattice dimensions at ?70°C: a = 1309.3, b = 1619.8, c = 2410.7 pm. Within the cations the boron atoms are linked to planar, asymmetrical B₂N₂ four-membered rings with B? N distances of 155.1 and 143.1 pm via the μ₂-N atoms of the NPEt₃ groups. [B₂Cl₂(NPⁱPr₃)₃]⁺BCl₄^? · CH₂Cl₂: Space group Pna2, Z = 4, R = 0.033 for reflections with I > 2σ(I). Lattice dimensions at ?70°C: a = 1976.5, b = 860.2, c = 2612.7 pm. Within the cations the boron atoms are linked to planar, asymmetrical B₂N₂ four-membered rings with B? N distances of 153.7 and 150.5 pm via the μ₂-N atoms of two of the NPⁱPr₃ groups. The third NPⁱPr₃ group is terminally connected to the sp²-hybridized boron atom with a B? N distance of 133.5 pm and with a B? N? P bond angle of 165.3°.     

Das Lanthan‐Dodekahydro‐closo‐Dodekaborat‐Hydrat [La(H2O)9]2[B12H12]3·15 H2O und sein Oxonium‐Chlorid‐Derivat [La(H2O)9](H3O)Cl2[B12H12]·H2O

The Lanthanum Dodecahydro‐closo‐Dodecaborate Hydrate [La(H₂O)₉]₂[B₁₂H₁₂]₃·15 H₂O and its Oxonium‐Chloride Derivative [La(H₂O)₉](H₃O)Cl₂[B₁₂H₁₂]·H₂O By neutralization of an aqueous solution of the free acid (H₃O)₂[B₁₂H₁₂] with basic La₂O₃ and after isothermic evaporation colourless, face‐rich single crystals of a water‐rich lanthanum(III) dodecahydro‐closo‐dodecaborate hydrate [La(H₂O)₉]₂[B₁₂H₁₂]₃·15 H₂O are isolated. The compound crystallizes in the trigonal system with the centrosymmetric space group (a = 1189.95(2), c = 7313.27(9) pm, c/a = 6.146; Z = 6; measuring temperature: 100 K). The crystal structure of [La(H₂O)₉]₂[B₁₂H₁₂]₃·15 H₂O can be characterized by two of each other independent, one into another posed motives of lattice components. The [B₁₂H₁₂]²⁻ anions (d(B–B) = 177–179 pm; d(B–H) = 105–116 pm) are arranged according to the samarium structure, while the La³⁺ cations are arranged according to the copper structure. The lanthanum cations are coordinated in first sphere by nine oxygen atoms from water molecules in form of a threecapped trigonal prism (d(La–O) = 251–262 pm). A coordinative influence of the [B₁₂H₁₂]²⁻ anions on La³⁺ has not been determined. Since “zeolitic” water of hydratation is also present, obviously the classical H–O^δ–···^+δH–O‐hydrogen bonds play a significant role in the stabilization of the crystal structure. During the conversion of an aqueous solution of (H₃O)₂[B₁₂H₁₂] with lanthanum trichloride an anion‐mixed salt with the composition [La(H₂O)₉](H₃O)Cl₂[B₁₂H₁₂]·H₂O is obtained. The compound crystallizes in the hexagonal system with the non‐centrosymmetric space group (a = 808.84(3), c = 2064.51(8) pm, c/a = 2.552; Z = 2; measuring temperature: 293 K). The crystal structure can be characterized as a layer‐like structure, in which [B₁₂H₁₂]²⁻ anions and H₃O⁺ cations alternate with layers of [La(H₂O)₉]³⁺ cations (d(La–O) = 252–260 pm) and Cl⁻ anions along [001]. The [B₁₂H₁₂]²⁻ (d(B–B) = 176–179 pm; d(B–H) = 104–113 pm) and Cl⁻ anions exhibit no coordinative influence on La³⁺. Hydrogen bonds are formed between the H₃O⁺ cations and [B₁₂H₁₂]²⁻ anions, also between the water molecules of [La(H₂O)₉]³⁺ and Cl⁻ anions, which contribute to the stabilization of the crystal structure.     

Isotype Borophosphate MII(C2H10N2)[B2P3O12(OH)] (MII = Mg,Mn, Fe,Ni, Cu,Zn): Verbindungen mit Tetraeder‐Schichtverbänden

Isotypic Borophosphates M^II(C₂H₁₀N₂)[B₂P₃O₁₂(OH)] (M^II = Mg, Mn, Fe, Ni, Cu, Zn): Compounds containing Tetrahedral Layers The isotypic compounds M^II(C₂H₁₀N₂) · [B₂P₃O₁₂(OH)] (M^II = Mg, Mn, Fe, Ni, Cu, Zn) were prepared under hydrothermal conditions (T = 170 °C) from mixtures of the metal chloride (chloride hydrate, resp.), Ethylenediamine, H₃BO₃ and H₃PO₄. The orthorhombic crystal structures (Pbca, No. 61, Z = 8) were determined by X‐ray single crystal methods (Mg(C₂H₁₀N₂)[B₂P₃O₁₂(OH)]: a = 936.81(2) pm, b = 1221.86(3) pm, c = 2089.28(5) pm) and Rietveld‐methods (M^II = Mn: a = 931.91(4) pm, b = 1234.26(4) pm, c = 2129.75(7) pm, Fe: a = 935.1(3) pm, b = 1224.8(3) pm, c = 2088.0(6) pm, Ni: a = 939.99(3) pm, b = 1221.29(3) pm, c = 2074.05(7) pm, Cu: a = 941.38(3) pm, b = 1198.02(3) pm, c = 2110.01(6) pm, Zn: a = 935.06(2) pm, b = 1221.33(2) pm, c = 2094.39(4) pm), respectively. The anionic part of the structure contains tetrahedral layers, consisting of three‐ and nine‐membered rings. The M^II‐ions are in a distorted octahedral or tetragonal‐bipyramidal [4 + 2] (copper) coordination formed by oxygen functions of the tetrahedral layers. The resulting three‐dimensional structure contains channels running along [010]. Protonated Ethylenediamine ions are fixed within the channels by hydrogen bonds.     

Zintl‐Anionen des Siliciums in den Halogeniden La3Cl2Si3 und La6Br3Si7

Zintl Anions of Silicon in the Halides La₃Cl₂Si₃ and La₆Br₃Si₇ La₃Cl₂Si₃ and La₆Br₃Si₇ are prepared at temperatures of around 950 °C from LaX₃ (X = Cl, Br), La metal and Si as starting materials. La₃Cl₂Si₃ crystallizes in C2/m with a = 1802(3), b = 420.6(4), c = 1058(2) pm, β = 97.9(2)°, and La₆Br₃Si₇ in Pmmn mit a = 1686.9(2), b = 412.93(11), c = 1185.2(1) pm. In both compounds the Si atoms are located in trigonal prisms of La atoms, which are connected through common triangular and rectangular faces to form layers. The bromine atoms connect the metal atom double layers. In La₃Cl₂Si₃ the Si atoms form zig‐zag chains, in La₆Br₃Si₇ chains build up from ‐connected Si₁₂ rings. Both compounds are metallic conductors.     

Preparation and crystal structure of the Isotypic Carbides Ln4Ni2C5 (Ln = Er,Tm, Yb and Lu)

The title compounds were prepared from the elemental components in a lithium flux. Their crystal structure was determined for the ytterbium compound from single-crystal X-ray data. It is orthorhombic, Pmm2, a = 352.88(6) pm, b = 1 143.0(3) pm, c = 366.16(6) pm, Z = 1, R = 0.020 for 1 261 structure factors and 29 variable parameters. The structure may be viewed as an intergrowth of slabs consisting of the CeNiC₂ and the ScC (NaCl type) structures. It thus contains C₂ pairs with a C? C distance of 138(1) pm and isolated carbon atoms. Together with the nickel atoms the C₂ pairs form one-dimensionally infinite building elements [Ni₂C₄]_n. The fifth carbon atom is octahedrally coordinated by ytterbium atoms. Accordingly the compound may be rationalized to a first approximation with the formula (Yb³⁺)₄[Ni₂C₄^8?]C^4?. Yb₄Ni₂C₅ shows Curie-Weiss behaviour with a magnetic moment of μ_exp = 4.44 μ_B per ytterbium atom in good agreement with the theoretical moment of μ_eff = 4.53 μ_B for Yb³⁺.     

Synthesis and Structure of Ba[ZrN2] and Ba2[NbN3]

Ba₃N₂ reacts at 950°C under pure N₂ with Zr to yield dark red, air-sensitive Ba[ZrN₂]. This new compound crystallizes in the tetragonal space group P4/nmm with a = 416.10(2), c = 839.2(1) pm and Z = 2. The crystal structure was solved and refined using X-ray and neutron powder diffraction data. In the nitrido zirconate [ZrN₂]^2? the Zr atoms exhibit a square-pyramidal coordination by five N atoms at distances of 201(3) and 220.2(2) pm. The pyramids share all the edges in the basal plane to form layers parallel to (001) with their apices alternately pointing up and down. The Ba²⁺ cations are integrated into these layers at the levels of the pyramidal apices. The structure can be interpreted as a stuffed PbFCl type. Ba₂[NbN₃] is formed by the reaction of Ba₃N₂ and NbN or of Ba and Nb at 1 000°C under N₂. Isostructural to Ba₂[TaN₃] it crystallizes in the monoclinic space group C2/c with a = 613.2(3), b = 1 176.8(3), c = 1 322.9(4) pm, β = 91.65(2)°, Z = 8. The nitrido niobate anions form chains of corner sharing NbN₄ tetrahedra with distances Nb? N between 188(1) and 199.9(9) pm.