LiSr2[ReN4] und LiBa2[ReN4] – isotype Nitridorhenate(VII)

LiSr₂[ReN₄] and LiBa₂[ReN₄] – isotypic Nitridorhenates(VII) The quaternary nitridorhenates(VII) LiAE₂[ReN₄] (AE = Sr, Ba) were synthesized by reaction of the metals with molecular nitrogen at 850–900 °C. The plate‐like, nearly colourless crystals were investigated by X‐ray single crystal methods and were identified as isotypic phases: LiSr₂[ReN₄] (LiBa₂[ReN₄]); monoclinic, P2₁/m; a = 614.64(8) pm (651.04(12) pm), b = 585.97(6) pm (b = 598.86(9) pm), c = 689.70(17) pm (737.43(5) pm), β = 106.375(4)° (108.535(2)°); Z = 2. Crystals of the strontium compound were systematically twinned along [001]. In the crystal structures of the quaternary compounds the alkaline earth‐ and nitride‐ ions are arranged in the motif of the InNi₂‐type structure. Strontium and barium are in a trigonal prismatic coordination by nitrogen (Sr–N: 261.0(7)–284.3(4) pm; Ba–N: 278.0(7)–303.0(6) pm). One half of the tetrahedral voids within the partial structure formed by stacking of trigonal prismatic rod layers is occupied by rhenium (formation of [Re^VIIN₄]^5–‐tetrahedra; Re–N: 181.0(6)–184.5(8) pm), lithium takes the positions of the remaining tetrahedral sites (Li–N: 2 × 198(1) pm, 224(2) pm and 228(2) pm for the strontium phase). In the barium compound the lithium positions show a larger shift from the tetrahedral centres towards a tetrahedral plane (Li–N: 2 × 195(1) pm, 213(2) pm and 304(2) pm).     

Ca3[BN2]I3: The First Halide‐Rich Alkaline Earth Nitrido­borate with Isolated [BN2]3– Units

The title compound Ca₃[BN₂]I₃ was obtained from reactions of mixtures of the starting materials Ca₃[BN₂]₂ and CaI₂ in a 1:4 ratio in sealed Nb tubes at 1223 K. The crystal structure was solved from powder synchrotron diffraction data. Ca₃[BN₂]I₃ is the first example of a halide‐rich nitridoborate crystallizing in the rhombohedral space group R32 [no. 155, Pearson code: hR96; Z = 12; a = 16.70491(2) Å, c = 12.41024(2) Å]. The crystal structure is built up by two interpenetrating networks of condensed edge‐sharing [BN₂]@Ca₆ and [□]@I₆ trigonal antiprisms (□ = void). In Ca₃[BN₂]I₃ two crystallograhically distinct [BN₂]^3– anions are present with d(B1–N) = 1.393(2) Å and d(B2–N) = 1.369(9) Å. Their bond angles are practically linear, varying only slightly: N–B1–N = 179(1)° and N–B2–N = 180°. Vibrational spectra were interpreted based on the D_∞h symmetry of the discrete linear [N–B–N]^3– moieties, considering the site symmetry reduction and the presence of two distinct [BN₂]^3– groups.     

Pniktogenidostannate(IV) mit isolierten Tetraeder‐Anionen: Neue Vertreter (E1)4(E2)2[Sn(E15)4] (mit E1 = Na,K; E2 = Ca,Sr, Ba; E15 = P,As, Sb,Bi) vom Na6[ZnO4]‐Typ und die Überstrukturvariante von K4Sr2[SnAs4]

Pnictogenidostannates(IV) with Discrete Tetrahedral Anions: New Representatives (E1)₄(E2)₂[Sn(E15)₄] (with E1 = Na, K; E2 = Ca, Sr, Ba; E15 = P, As, Sb, Bi) of the Na₆[ZnO₄] Type and the Superstructure Variant of K₄Sr₂[SnAs₄] The silvery to dark metallic lustrous compounds (E1)₄(E2)₂[Sn(E15)₄] (E1 = Na, K; E2 = Ca, Sr, Ba; E15 = P, As, Sb, Bi) were prepared from melts of stoichiometric mixtures of the elements. They crystallize in the Na₆[ZnO₄]‐type structure (hexagonal, space group: P6₃mc, Z = 2; Na₄Ca₂[SnP₄]: a = 938.94(7), c = 710.09(8) pm; K₄Sr₂[SnAs₄]: a = 1045.0(2), c = 767.0(1) pm; K₄Ba₂[SnP₄]: a = 1029.1(6), c = 780.2(4) pm; K₄Ba₂[SnAs₄]: a = 1051.3(1), c = 795.79(7) pm; K₄Ba₂[SnSb₄]: a = 1116.9(2), c = 829.2(1) pm; K₄Ba₂[SnBi₄]: a = 1139.5(2), c = 832.0(2) pm). The anionic partial structure consists of tetrahedra [Sn(E15)₄]^8– orientated all in the same direction along [001]. In the cationic partial structure one of the two cation positions is occupied statistically by alkali and alkaline earth metal atoms. Up to now only for K₄Sr₂[SnAs₄] a second modification could be isolated, forming a superstructure type with three times the unit cell volume (hexagonal, space group: P6₃cm, Z = 6; a = 1801.3(2), c = 767.00(9) pm) and an ordered cationic partial structure.     

Darstellung,Kristallstrukturen und Schwingungsspektren von Verbindungen mit den linearen Dipnictidoborat(3–)‐Anionen [P–B–P]3–, [As–B–As]3– und [P–B–As]3–

Synthesis, Crystal Structure, and Vibrational Spectra of Compounds with the Linear Dipnictidoborate (3–) Anions [P–B–P]^3–, [As–B–As]^3–, and [P–B–As]^3– The alkali metal boron compounds M₃[BX₂] with X = P, As are synthesized from the alkali metals M and the binary components MX or M₄X₆ and BX in sealed steel ampoules (phosphides) or niobium ampoules (arsenides) at 1000 K. The compounds are obtained as bright yellow prisms (M₃[BP₂]) or plates (K₂Na[BP₂]) and yellow‐red prismatic crystals (M₃[BAs₂], Cs₃[BPAs]) which are very sensitive against oxidation and hydrolysis. Three different structure types are formed, namely K₂Na[BP₂] (C2/m (No. 12); Z = 4; a new mC24 structure type); Na₃[BP₂] (P2₁/c (No. 14); Z = 4, β‐Li₃[BN₂] type), M₃[BX₂] with M = K, Rb, Cs and X = P, As and Cs₃[P–B–As] (C2/c, (No. 15); Z = 4, K₃[BP₂] type). The bond lengths of the linear [BX₂]^3– anions are hardly changed and correspond to a Pauling bond order PBO = 1.9 (d(B–P) = 176.7–177.1 pm; d(B–As) = 186.5–188.0 pm). The vibrational spectra confirm the existence of unmixed and mixed units [P–B–P]^3–, [As–B–As]^3– and [P–B–As]^3– with D_∞h and C_∞v symmetry, respectively. The valence force constants f(B–X) and the corresponding Siebert bond orders, calculated from the frequencies, are discussed and compared with those of the isoelectronic anions and molecules.     

Na3[BN2] and Na2K[BN2]: A Known and a Novel Alkali Metal Dinitridoborate Obtained via Mild Thermal Dehydrogenation

Na₃[BN₂] and Na₂K[BN₂] were obtained as white polycrystalline powders from the reaction of the respective binary mixtures NaNH₂:NaBH₄ and NaNH₂:KBH₄ in molar ratio 2:1 at 873 K and 683 K, respectively, in an argon stream. According to the results of thermal analysis measurements, both compounds are thermally stable only up to 954 K (Na₃[BN₂]) and 712 K (Na₂K[BN₂]), respectively, decomposing under evolution of alkali metal and nitrogen to yield hexagonal BN as final residue, which was identified from powder patterns. The crystal structure of Na₃[BN₂] {β‐Li₃[BN₂] type; P2₁/c (No. 14); Z = 4} was confirmed and the unit cell parameters redetermined: a = 5.724(1) Å, b = 7.944(1) Å, c = 7.893(1) Å, β = 111.31(1)°. According to X‐ray powder data, Na₂K[BN₂] crystallizes isotypic to Na₂KCuO₂ in the tetragonal space group I4/mmm (No. 139) with a = 4.2359(1) Å, c = 10.3014(2) Å and Z = 2. The crystal structure of Na₂K[BN₂] is composed of linear [N–B–N]^3– anions centering elongated M₁₄ rhombic dodecahedra, which are formed by 8 sodium and 6 potassium atoms. The [BN₂]@Na_8/4K_6/6 polyhedra are stacked along [001] and condensed via common tetragonal faces to generate a space‐filling 3D arrangement. The B–N bond lengths for the strictly linear [N–B–N]^3– units are 1.357(4) Å. Vibrational spectra of the title compounds were measured and analyzed based on D_∞h symmetry of the relevant [N–B–N]^3– groups taking into account the site symmetry effects for Na₃[BN₂]. Both the wavenumbers, as well as the calculated valence force constants f(B–N) = 7.29 N · cm^–1 (Na₃[BN₂]) and 7.33 N · cm^–1 (Na₂K[BN₂]), respectively, are in good agreement with those of the known alkali and alkaline earth dinitridoborates.     

Dodekahydro‐closo‐dodekaborate der schweren Erdalkalimetalle aus wäßriger Lösung: Ca(H2O)7[B12H12] · H2O,Sr(H2O)8[B12H12] und Ba(H2O)6[B12H12]

Dodecahydro‐ closo ‐dodecaborates of the Heavy Alkaline‐Earth Metals from Aqueous Solution: Ca(H₂O)₇[B₁₂H₁₂] · H₂O, Sr(H₂O)₈[B₁₂H₁₂], and Ba(H₂O)₆[B₁₂H₁₂] The crystalline hydrates of the heavy alkaline earth metal dodecahydro‐closo‐dodecaborates (M[B₁₂H₁₂] · n H₂O, n = 6–8; M = Ca, Sr, Ba) are easily accessible by reaction of an aqueous (H₃O)₂[B₁₂H₁₂] solution with an alkaline earth metal carbonate (MCO₃). By isothermic evaporation of the respective aqueous solution we obtained colourless single crystals which are characterized by X‐ray diffraction at room temperature. The three compounds Ca(H₂O)₇[B₁₂H₁₂] · H₂O (orthorhombic, P2₁2₁2₁; a = 1161.19(7), b = 1229.63(8), c = 1232.24(8) pm; Z = 4), Sr(H₂O)₈[B₁₂H₁₂] (trigonal, R3; a = 1012.71(6), c = 1462.94(9) pm; Z = 3) and Ba(H₂O)₆[B₁₂H₁₂] (orthorhombic, Cmcm; a = 1189.26(7) pm, b = 919.23(5) pm, c = 1403.54(9) pm; Z = 4) are neither formula‐equal nor isostructural. The structure of Sr(H₂O)₈[B₁₂H₁₂] is best described as a NaCl‐type arrangement, Ba(H₂O)₆[B₁₂H₁₂] rather forms a layer‐like and Ca(H₂O)₇[B₁₂H₁₂] · H₂O a channel‐like structure. In first sphere the alkaline earth metal cations Ca²⁺ and Sr²⁺ are coordinated by just seven and eight oxygen atoms from the surrounding water molecules, respectively. A direct coordinative influence of the quasi‐icosahedral [B₁₂H₁₂]^2– cluster anions becomes noticeable only for the Ba²⁺ cations (CN = 12) in Ba(H₂O)₆[B₁₂H₁₂]. The dehydratation of the alkaline earth metal dodecahydro‐closo‐dodecaborate hydrates has been shown to take place in several steps. Thermal treatment leads to the anhydrous compounds Ca[B₁₂H₁₂], Sr[B₁₂H₁₂] and Ba[B₁₂H₁₂] at 224, 164 and 116 °C, respectively.     

Magnetic Investigations and 151Eu Mössbauer Spectroscopy of MYbSi4N7 with M = Sr,Ba, Eu

The isotypic nitridosilicates MYb[Si₄N₇] (M = Sr, Ba, Eu) were obtained by the reaction of the respective metals with Si(NH)₂ in a radiofrequency furnace below 1600 °C. On the basis of powder diffraction data of MYb[Si₄N₇] Rietveld refinements of the lattice constants were performed; these confirmed the previously published single‐crystal data. The compounds contain a condensed network of corner‐sharing [N(SiN₃)₄] units. The central nitrogen thus exhibits ammonium character. Magnetic susceptibility measurements of MYb[Si₄N₇] (M = Sr, Ba, Eu) show paramagnetic behavior with experimental magnetic moments of 3.03(2), (Sr), 2.73(2) (Ba), and 9.17(2) (Eu) μ_B per formula unit. In EuYbSi₄N₇ the europium and ytterbium atoms are in stable divalent and trivalent states, respectively. According to the non‐magnetic character of the alkaline earth cations, ytterbium has to be in an intermediate valence state Yb^III‐x in the strontium and barium compound. Consequently, either a partial exchange N^3—/O^2— resulting in compositions MYb^III‐x[Si₄N_7—xO_x] or an introduction of anion defects according to MYb^III‐x[Si₄N_7—x/3□_x/3] has to be assumed. The phase width 0 ≤ x ≤ 0.4 was estimated according to the magnetic measurements. ¹⁵¹Eu Mössbauer spectra of EuYb[Si₄N₇] at 78 K show a single signal at an isomer shift of δ = —12.83(3) mm s^—1 subject to quadrupole splitting of ΔE_Q = 5.7(8) mm s^—1, compatible with purely divalent europium.     

Vibrational Spectra and Magnetic Properties of Eu3[BN2]2 and LiEu4[BN2]3

Eu₃[BN₂]₂ and LiEu₄[BN₂]₃ were synthesized from a stoichiometric mixture of EuN, BN, europium metal and Li₃N, EuN and BN (ratio: 1:4:3) in sealed niobium ampoules at 1475 and 1275 K, respectively. Temperature dependent susceptibility measurements of Eu₃[BN₂]₂ and LiEu₄[BN₂]₃ show Curie‐Weiss behavior with experimental magnetic moments of 8.03(5) and 8.5(1) μ_B/Eu atom, respectively, compatible with divalent europium. Both nitridoborates order ferromagnetically at T_C = 32.0(5) K (Eu₃[BN₂]₂) and 22.0(5) K (LiEu₄[BN₂]₃). The saturation magnetizations of 5.73(5) μ_B/Eu atom at 5 K and 7 T for Eu₃[BN₂]₂ and 4.2 μ_B/Eu atom at 5 K and 2 T for LiEu₄(BN₂)₃ are smaller than the maximum value of 7 μ_B. ¹⁵¹Eu Mössbauer data of Eu₃[BN₂]₂ at 4.2 K show an isomer shift of —11.4(1) mm/s and an experimental line width of 3.1(2) mm/s. Full magnetic hyperfine field splitting with 26.2(3) T at the europium nuclei is detected. Vibrational spectra of Eu₃[BN₂]₂ are interpreted on the basis of discrete [BN₂]^3— units with symmetry D_∞h by taking into account the existence of two crystallographically independent [BN₂]^3— anions and their dynamic coupling in the unit cell (factor group splitting).     

Schwache Sn…I‐Wechselwirkungen in den Kristallstrukturen der Iodostannate [SnI4]2– und [SnI3]–

Weak Sn…I Interactions in the Crystal Structures of the Iodostannates [SnI₄]^2– and [SnI₃]^– Iodostannate complexes can be crystallized from SnI₂ solutions in polar organic solvents by precipitation with large counterions. Thereby isolated anions as well as one, two or three‐dimensional polymeric anionic substructures are established, in which SnI₃^– and SnI₄^2– groups are linked by weak Sn…I interactions. Examples are the iodostannates [Me₃N–(CH₂)₂–NMe₃][SnI₄] ( 1 ), (Ph₄P)₂[Sn₂I₆] ( 2 ), [Me₃N–(CH₂)₂–NMe₃][Sn₂I₆] ( 3 ), [Fe(dmf)₆][SnI₃]₂ ( 4 ) and (Pr₄N)[SnI₃] ( 5 ), which have been characterized by single crystal X‐ray diffraction. [Me₃N–(CH₂)₂–NMe₃][SnI₄] ( 1 ): a = 671.6(2), b = 1373.3(4), c = 2046.6(9) pm, V = 1887.7(11) · 10⁶ pm³, space group Pbcm;(Ph₄P)₂[Sn₂I₆] ( 2 ): a = 1168.05(6), b = 717.06(4), c = 3093.40(10) pm, β = 101.202(4)°, V = 2541.6(2) · 10⁶ pm³, space group P2₁/n;[Me₃N–(CH₂)₂–NMe₃][Sn₂I₆] ( 3 ): a = 695.58(4), b = 1748.30(8), c = 987.12(5) pm, β = 92.789(6)°, V = 1199.00(11) · 10⁶ pm³, space group P2₁/c;[Fe(dmf)₆][SnI₃]₂ ( 4 ): a = 884.99(8), b = 1019.04(8), c = 1218.20(8) pm, α = 92.715(7), β = 105.826(7), γ = 98.241(7), V = 1041.7(1) · 10⁶ pm³, space group P1;(Pr₄N)[SnI₃] ( 5 ): a = 912.6(2), b = 1205.1(2), c = 1885.4(3) pm, V = 2073.5(7) · 10⁶ pm³, space group P2₁2₁2₁.     

Das SCN–-Ion als ambidenter Ligand – Synthese und Kristallstrukturen von (Bu4N)4[Ag2Fe2(SCN)12] und (Et4N)2 [Ag2Fe(SCN)6]

The SCN^– Ion as an Ambidentate Ligand – Synthesis and Crystal Structures of (Bu₄N)₄[Ag₂Fe₂(SCN)₁₂] and (Et₄N)₂ [Ag₂Fe(SCN)₆] In (Bu₄N)₄[Ag₂Fe₂(SCN)₁₂] · 2 CH₃NO₂ ( 1 ) and (Et₄N)₂[Ag₂Fe(SCN)₆] ( 2 ) the ambidentate SCN^– anions link Ag⁺ with Fe³⁺ and Fe²⁺ centers, respectively. The tetranuclear anions in 1 are built from [Fe(NCS)₆]^3– groups connected by Ag⁺ ions. In 2 the same bridging pattern leads to polymeric anionic chains containing [Fe(NCS)₆]^4– groups linked by Ag⁺ ions. (Bu₄N)₄[Ag₂Fe₂(SCN)₁₂] · 2 CH₃NO₂ ( 1 ): a = 1184.10(10), b = 1370.80(10), c = 1776.5(2) pm, α = 99.090(10), β = 102.100(10), γ = 100.360(10)°, V = 2715.5(4) · 10⁶ pm³, space group P1; (Et₄N)₂[Ag₂Fe(SCN)₆] ( 2 ): a = 1607.0(2), b = 1006.92(9), c = 1096.13(9) pm, V = 1773.7(3) · 10⁶ pm³, space group Pnnm.     

M(SCN)2 (M = Eu,Sr, Ba): Kristallstruktur,thermisches Verhalten,Schwingungsspektroskopie

M(SCN)₂ (M = Eu, Sr, Ba): Crystal Structure, Thermal Behaviour, Vibrational Spectroscopy Single crystals of M(SCN)₂ (M = Eu, Sr, Ba) have been obtained via metathesis of NaSCN and MCl₂ (M = Eu, Sr, Ba) at 340 °C. The isotypic crystal structures of the thiocyanates M(SCN)₂ (C2/c, Z = 4, Eu: a = 979.3(2), b = 660.8(1), c = 815.7(2) pm, β = 91.58(3)°, R_all = 0.0245, Sr: a = 985.5(2), b = 662.9(2), c = 819.6(2) pm, β = 91.29(3)°, R_all = 0.0435, Ba: a = 1018.8(2), b = 687.2(1), c = 852.2(1) pm, β = 92.43(2)°, R_all = 0.0392) contain alternating layers of M²⁺ and SCN^–. According to M(SCN)_4/4(NCS)_4/4 M²⁺ is eight‐coordinated by four sulfur and four nitrogen atoms forming a square antiprism. Thermal investigations show that the compounds melt without decomposition. Vibrational spectroscopic investigations are presented and discussed.     

Darstellung von Tetramethylammoniumazidsulfit und Tetramethylammoniumcyanat‐Schwefeldioxid‐Addukt, [(CH3)4N]+[SO2N3]–, [(CH3)4N]+ [SO2OCN]– und Kristallstruktur von [(CH3)4N]+[SO2N3]–

Preparation of Tetramethylammonium Azidosulfite and Tetramethylammonium Cyanate Sulfur Dioxide‐Adduct, [(CH₃)₄N]⁺[SO₂N₃]^–, [(CH₃)₄N]⁺[SO₂OCN]^– and Crystal Structure of [(CH₃)₄N]⁺[SO₂N₃]^– Tetramethylammonium azide forms with sulfur dioxide an azidosulfite salt. It is characterized by NMR and vibrational spectroscopy and the crystal structure analysis. [(CH₃)₄N]⁺[SO₂N₃]^– crystallizes in the monoclinic space group P2₁/c with a = 551.3(1) pm, b = 1095.2(1) pm, c = 1465.0(1) pm, β = 100.63(1)°, and four formula units in the unit cell. The crystal structure possesses a strong S–N interaction between the N^3– anions and the SO₂ molecules. The S–N distance of 200.5(2) pm is longer than a covalent single S–N bond. The structure is compared with ab initio calculated data. Furthermore an adduct of tetrametylammonium cyanate and sulfur dioxide is reported. It is characterised by NMR and vibrational spectroscopy. The structure is calculated by ab initio methods.     

Synthesis and Characterization of the Chain Borosulfates (NH4)3[B(SO4)3] and Sr[B2(SO4)4]

Two new borosulfates were obtained either by an open vessel synthesis from sulfuric acid and B(OH)₃, yielding (NH₄)₃[B(SO₄)₃] or from solvothermal synthesis in oleum enriched sulfuric acid and B(OH)₃, yielding Sr[B₂(SO₄)₄]. (NH₄)₃[B(SO₄)₃] crystallizes homeotypic to K₃[B(SO₄)₃] in space group Ibca (Z = 8, a = 728.58(3) pm, b = 1470.84(7) pm, c = 2270.52(11) pm), comprising open branched vierer single chains {¹_∞[B(SO₄)₂(SO₄)_2/2]^3–}. Sr[B₂(SO₄)₄] crystallizes as an ordered variant of Pb[B₂(SO₄)₄] in space group Pnna (Z = 4, a = 1257.4(4) pm, b = 1242.1(4) pm, c = 731.9(2) pm), consisting of loop branched vierer single chains {¹_∞[B(SO₄)_4/2]^2–}. Vibrational spectroscopy confirms both refined structure models. Thermal analysis of the dried powders, showed a decomposition towards the binary and ternary components, whereas a thermal treatment in the presence of the mother liquor promotes a decomposition of Sr[B₂(SO₄)₄] towards Sr[B₂O(SO₄)₃].     

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.     

Ba[CoN]: Ein niedervalentes Nitridocobaltat mit gewinkelten Ketten [CoN2/22−]

Ba[CoN]: A Low-Valency Nitridocobaltate with Angled Chains [CoN_2/2^2?] Ba[CoN] is prepared by reaction of barium and cobalt (molar ratio Ba : Co = 1 : 2.5) in tantalum crucibles at 870°C with flowing nitrogen (1 atm) within a period of 96 h. After cooling down to room temperature (24°C/h) black single crystals of the ternary phase with a platy habit are obtained (orthorhombic, Pnma; a = 959.9(2) pm, b = 2 351.0(3) pm, c = 547.6(2) pm; Z = 20). The crystal structure of Ba[CoN] contains angled (planar) chains [CoN_2/2^2?] which run along the [010]-direction (N? Co? N[°]: 178.5(5), 179.6(6), 180.0; Co? N? Co[°]: 82.9(6), 84.2(5), 177.1(8); Co? N[pm]: 174.6(12), 177.2(12), 181.9(13), 184.3(13), 187.1(12)). Nitrogen is in an octahedral coordination (N Ba₄Co₂) and is arranged in a distorted cubic close packing. Barium occupies one half of the tetrahedral holes (Ba? N[pm]: 274.8(16) ? 308.2(12)). The cis-positions of the Co-atoms at the nitrogen coordination-octahedra cause short Co? Co contacts within the chains [CoN_2/2^2?]. Through this, Co₂-units (Co? Co[pm]: 247.8(4); bridged by nitrogen) and linear Co₃-groups (Co? Co [pm]: 245.5(2); Co? Co? Co[°]: 180.0; bridged by nitrogen) alternate along the chains. The crystal structure of Ba[CoN] is closely related to the Ba[NiN] type structure.     

Novel Barium Beryllates Ba[Be2N2] and Ba3[Be5O8]: Syntheses,Crystal Structures and Bonding Properties

Ba[Be₂N₂] was prepared as a yellow‐green microcrystalline powder by reaction of Ba₂N with Be₃N₂ under nitrogen atmosphere. The crystal structure Rietfeld refinements (space group I4/mcm, a = 566.46(5) pm, c = 839.42(9) pm, R_int = 4.73 %, R_prof = 9.16 %) reveal the compound to crystallize as an isotype of the nitridoberyllates A[Be₂N₂] (A = Ca, Sr) consisting of planar 4.8² nets of mutually trigonal planar coordinated Be and N species. Averaged magnetic susceptibility values for the anion [(Be₂N₂)^2?] determined from measurements on A[Be₂N₂] with A = Mg, Ca, Ba allow to derive a diamagnetic increment for N^3? χ_dia = (?13±1stat.) · 10^?6emu mol^?1. Colorless Ba₃[Be₅O₈] was first obtained as an oxidation product of Ba[Be₂N₂] in air. The crystal structure was solved and refined from single crystal X‐ray diffaction data (space group Pnma, a = 942.9(1) pm, b = 1163.47(7) pm, c = 742.1(1) pm, R1 = 2.99 %, wR2 = 7.15 %) and contains infinite rods of Be in trigonal planar, tetrahedral and 3 + 1 coordination by O. The crystal structure is discussed in context with other known oxoberyllates. Electronic structure calculations and electron localization function diagrams for both compounds support the classification as nitrido‐ and oxoberyllate, respectively.     

K2NdP2S7: A Mixed‐Valent Neodymium(III) Thiophosphate According to K4Nd2[PS4]2[P2S6] with Discrete [PS4]3– and [S3P–PS3]4– Anions

Pale blue, lath‐shaped single crystals of K₂NdP₂S₇ (≡ K₄Nd₂[PS₄]₂[P₂S₆]; monoclinic, P2₁/n, a = 904.76(8), b = 677.38(6), c = 1988.7(2) pm, β = 97.295(5)°, Z = 2) are obtained by the reaction of Nd, S and P₂S₅ with an excess of KCl as a flux in evacuated silica tubes at 750 °C (7 d) which should produce Nd[PS₄] instead. Beside isolated [PS₄]^3– tetrahedra, the crystal structure contains discrete ethane‐analogous [P₂S₆]^4– (≡ [S₃P–PS₃]^4–) units in staggered conformation with tetravalent phosphorus cations and a P–P distance of 219 pm. The two crystallographically different potassium cations show coordination numbers of nine and ten in the shape of distorted mono‐ and bicapped square antiprisms. Finally, the Nd³⁺ cations are surrounded by eight sulfur atoms arranged as (uncapped) square antiprisms. The entire structure is dominated by (K1)⁺ containing {(Nd₂[PS₄]₂[P₂S₆])^4–} layers parallel (101) which are three‐dimensionally interconnected by (K2)⁺ cations.     

SeBr3[AlBr4] und TeI3[AlI4] – zwei weitere Vertreter des SCl3[AlCl4]-Strukturtyps

SeBr₃[AlBr₄] and TeI₃[AlI₄] – two further Compounds in the SCl₃[AlCl₄] Structure Type The reaction of SeBr₄ and AlBr₃ in a closed glass ampoule at 150°C yields quantitatively SeBr₃[AlBr₄] in form of yellow moisture sensitive crystals. From Te, two equivalents of I₂, and AlI₃ one obtains TeI₃[AlI₄] in form of dark red, moisture sensitive crystals. Both compounds crystallize monoclinic in the space group Pc (SeBr₃[AlBr₄]: a = 670.7(7) pm, b = 663.9(5) pm, c = 1 428.6(2) pm, β = 101.21(9)°, TeI₃[AlI₄]: a = 731.9(1) pm, b = 730.8(1) pm, c = 1 565.5(3) pm, β = 102.01(2)°). They are isotypic and have the SCl₃[AlCl₄] structure type. The structures are built of tetrahedral AlX₄^? ions and of pyramidal EX₃⁺ ions (E = S, Se, Te; X = Cl, Br, I). The chalcogen atoms are additionally coordinated by halogen atoms of surrounding AlX₄^? ions, corresponding to a strongly distorted octahedral coordination EX₃₊₃.     

[CoN2]/[CN2]‐Substitution in a Crystalline Phase with Composition Close to Sr6[CoN2]2[CN2]

Sr₆[CoN₂]₂[CN₂] was prepared from Sr₂N, carbon, cobalt, and NaN₃ as nitrogen source. The crystal structure (I4/mmm (no. 139), a = 383.55(10) pm, c = 1237.8(4) pm) represents a Na₂[HgO₂] type arrangement with both linear [Co^IN₂]^5– and smaller [CN₂]^2– ions mutually occupying the [HgO₂] position.     

Chromhexacyano‐Komplexe: Die Kristallstrukturen der Cyanoelpasolithe (NMe4)2ACr(CN)6 (A = K,Cs) und der kubischen Bariumverbindung Ba3[Cr(CN)6]2 · 20 H2O

Chromium Hexacyano Complexes: The Crystal Structures of the Cyano Elpasolites (NMe₄)₂ACr(CN)₆ (A = K, Cs) and of the Cubic Barium Compound Ba₃[Cr(CN)₆]₂ · 20 H₂O The crystal structures of the cyano elpasolites (NMe₄)₂KCr(CN)₆ (a = 1527.3(1), b = 888.1(1), c = 1539.0(1) pm, β = 109.92(1)°; C2/c, Z = 4) and (NMe₄)₂CsCr(CN)₆ (a = 1278.9(1) pm; Fm3m, Z = 4), as well as of the cubic compound Ba₃[Cr(CN)₆]₂ · 20 H₂O (a = 1631.0(1) pm; Im3m, Z = 4) were determined by X‐ray methods with single crystals. Reasons for the enlarged distances within the [Cr(CN)₆]^3–‐octahedron of the K compound (Cr–C: 209.3 pm) compared to the observations within both cubic complexes (206.1 resp. 206.9 pm) are discussed in context with the tolerance factors of cyano elpasolites. As is the case there concerning the cyano bridges Cr–CN–A towards the alkali ions the novel structure type of the barium compound, too, exhibits nearly linear bridging towards Ba. It contributes, however, only four N ligands to the ninefold [BaN₄O₅] coordination; part of the aqua ligands show disorder (Ba–N: 287.5, Ba–O: 281/293 pm).