M+M3+2As(HAsO4)6 and α‐ and β‐M+M3+(HAsO4)2 (M+M3+ = RbAl or CsFe): six new compounds crystallizing in three closely related structure types

The crystal structures of hydrothermally synthesized (T = 493 K, 7–9 d) rubidium aluminium bis[hydrogen arsenate(V)], RbAl(HAsO₄)₂, caesium iron bis[hydrogen arsenate(V)], CsFe(HAsO₄)₂, rubidium dialuminium arsenic(V) hexakis[hydrogen arsenate(V)], RbAl₂As(HAsO₄)₆, and caesium diiron arsenic(V) hexakis[hydrogen arsenate(V)], CsFe₂As(HAsO₄)₆, were solved by single‐crystal X‐ray diffraction. The four compounds with the general formula M⁺M³⁺(HAsO₄)₂ adopt the RbFe(HPO₄)₂ structure type (Rc) and a closely related new structure type, which is characterized by a different stacking order of the building units, leading to noncentrosymmetric space‐group symmetry R32. The second new structure type, with the general formula M⁺M³⁺₂As(HAsO₄)₆ (Rc), is also a modification of the RbFe(HPO₄)₂ structure type, in which one third of the M³⁺O₆ octahedra are replaced by AsO₆ octahedra, and two thirds of the voids in the structure, which are usually filled by M⁺ cations, remain empty to achieve charge balance.     

M2Ga6Te10 (M: Li,Na): Two New Non‐metallic Filled β‐Manganese Phases – X‐ray and NMR Studies

Two new non‐metallic filled β‐manganese phases M₂Ga₆Te₁₀ (M: Li, Na) are obtained as black, homogeneous, microcristalline samples as well as single crystals by direct reaction of the elements. According to the single crystal structure determinations both compounds crystallize in space group R32 (No. 155, Z = 2) with the lattice constants: a = 1436.9(2), c = 1759.0(4) pm (T = 180 K, Li₂Ga₆Te₁₀) and a = 1458(1) pm, c = 1776.1(4) pm (T = 290 K, Na₂Ga₆Te₁₀). Their structures are characterized by tetrahedral close packings of Te^2–, corresponding to the arrangement of Mn atoms in β‐Mn. While Ga³⁺ ions are distributed in an ordered way over 12% of the tetrahedral holes, the M⁺ ions occupy all distorted octahedral (“metaprismatic”) holes. As the Li⁺ ions are too small they occupy off‐center positions inside the metaprisms. Positions with the strongest off‐centering can only be refined on the basis of a split model. MAS‐NMR measurements, including multiple quantum NMR, allowed the two different crystallographic M⁺ sites to be distinguished unambigously by separate ⁷Li and ²³Na signals, respectively. The assignment of the NMR signals was supported by measurements of samples in which Li⁺ was partly substituted by larger cations (Sn²⁺, Pb²⁺).     

The novel arsenate Na4Co7−xAl2/3x(AsO4)6 (x = 1.37): crystal structure,charge‐distribution and bond‐valence‐sum investigations

The title compound, tetrasodium cobalt aluminium hexaarsenate, Na₄Co_7−xAl_2/3x(AsO₄)₆ (x = 1.37), is isostructural with K₄Ni₇(AsO₄)₆; however, in its crystal structure, some of the Co²⁺ ions are substituted by Al³⁺ in a fully occupied octahedral site (site symmetry 2/m) and a partially occupied tetrahedral site (site symmetry 2). A third octahedral site is fully occupied by Co²⁺ ions only. One of the two independent tetrahedral As atoms and two of its attached O atoms reside on a mirror plane, as do two of the three independent Na⁺ cations, all of which are present at half‐occupancy. The proposed structural model based on a careful investigation of the crystal data is supported by charge‐distribution (CHARDI) analysis and bond‐valence‐sum (BVS) calculations. The correlation between the X‐ray refinement and the validation results is discussed.     

Nd5(AsO3)4Cl3: The First Oxo‐Arsenate(III)‐Chloride of the Lanthanides

Single crystals of Nd₅(AsO₃)₄Cl₃ (monoclinic, P2/n, Z = 2, a = 1026.0(1), b = 543.35(3), c = 1400.2(1) pm, β = 93.48(1)°) were obtained from the reaction of Nd₂O₃, As₂O₃ and NaCl in a sealed silica ampoule. In the crystal structure the Nd³⁺ ions are linked by AsO₃^3? groups into layers that alternate with layers of Cl^? ions. Two of the three crystallographically different Nd³⁺ ions are coordinated by eight oxygen atoms, the third one has four oxygen and four chlorine atoms as neighbours.     

Variationen modulo 4–4+, 4+3–3+4–, 4–5+, 5–4+4–5+4–4+ bei Seltenerdcarbidhalogeniden

The new compounds Pr₈(C₂)₄Cl₅ (1), Pr₁₄(C₂)₇Cl₉ (2), Pr₂₂(C₂)₁₁Cl₁₄ (3), Ce₂(C₂)Cl (4), La₂(C₂)Br (5), Ce₂(C₂)Br (6), Pr₂(C₂)Br (7), Ce₁₈(C₂)₉Cl₁₁ (8), and Ce₂₆(C₂)₁₃Cl₁₆ (9) were prepared by heating mixtures of LnX₃, Ln and carbon or in an alternatively way LnX₃, and “Ln₂C_3–x” in appropriate amounts for several days between 750 and 1200 °C. The crystal structures were investigated by X‐ray powder analysis (5–7) and/or single crystal diffraction (1–4, 8, 9). Pr₈(C₂)₄Cl₅ crystallizes in space group P2₁/c with the lattice parameters a = 7.6169(12), b = 16.689(2), c = 6.7688(2) Å, β = 103.94(1) °, Pr₁₄(C₂)₇Cl₉ in Pc with a = 7.6134(15), b = 29.432(6), c = 6.7705(14) Å, β = 104.00(3) °, Pr₂₂(C₂)₁₁Cl₁₄ in P2₁/c with a = 7.612(2), b = 46.127(9), c = 6.761(1) Å, β = 103.92(3) °, Ce₂(C₂)₂Cl in C2/c with a = 14.573(3), b = 4.129(1), c = 6.696(1) Å, β = 101.37(3) °, La₂(C₂)₂Br in C2/c with a = 15.313(5), b = 4.193(2), c = 6.842(2) Å, β = 100.53(3) °, Ce₂(C₂)₂Br in C2/c with a = 15.120(3), b = 4.179(1), c = 6.743(2) Å, β = 101.09(3) °, Pr₂(C₂)₂Br in C2/c with a = 15.054(5), b = 4.139(1), c = 6.713(3) Å, β = 101.08(3) °, Ce₁₈(C₂)₉Cl₁₁ in P$\bar{1}$ with a = 6.7705(14), b = 7.6573(15), c = 18.980(4) Å,α = 88.90(3) °, β = 80.32(3) °, γ = 76.09(3) °, and Ce₂₆(C₂)₁₃Cl₁₆ in P2₁/c with a = 7.6644(15), b = 54.249(11), c = 6.7956(14) Å, β = 103.98(3) ° The crystal structures are composed of Ln octahedra centered by C₂ dumbbells. Such Ln₆(C₂)‐octahedra are condensed into chains which are joined into undulated sheets. In compounds 1–4 three and four up and down inclined ribbons alternate (4₊4_–, 4₊3_–3₊4_–, 4₊4_–3₊4_–4₊3_–), in compounds 8 and 9 four and five (4₊5_–, 5₊4_–4₊5_–4₊4_–), and in compounds 4–7 one, one ribbons (1₊1_–) are present. The Ln‐(C₂)‐Ln layers are separated by monolayers of X atoms.     

β‐LiMoO2(AsO4)

A new non‐centrosymmetrical form of lithium molybdyl arsenate has been synthesized and grown as a single crystal. The structure of β‐LiMoO₂(AsO₄) is built up of corner‐sharing AsO₄ tetrahedra and MoO₆ octahedra which form a three‐dimensional framework containing tunnels running along the a axis, wherein the Li⁺ cations are located. This novel structure is compared with the compound LiMoO₂(AsO₄) of the same formula, and with those of AMO₂(XO₄) (A is Na, K, Rb or Pb, M is Mo or V, and X is P or As) and B(MoO₂)₂(XO₄)₂ (B is Ba, Pb or Sr).     

Die Oxidnitridselenide M3ONSe2 dreiwertiger Lanthanoide (M = Ce – Nd)

The Oxide Nitride Selenides M₃ONSe₂ of Trivalent Lanthanoids (M = Ce – Nd) Oxide nitride selenides of the trivalent lanthanoids (M = Ce – Nd) with the composition M₃ONSe₂ can be prepared by the oxidation of the respective lanthanoid metal with selenium and sodium azide (NaN₃) in presence of impurities containing oxygen when the corresponding lanthanoid trichloride (MCl₃) is used as sodium trap for the coformation of NaCl. The thermal treatment of these mixtures along with additional NaCl as flux at 900 °C in evacuated silica tubes secures the formation of fawn, transparent, lath‐shaped crystals. The monoclinic structure (C2/m, Z = 6) was determined from X‐ray single‐crystal diffraction data (Ce₃ONSe₂: a = 2480.51(14), b = 406.85(3), c = 952.83(6) pm, β = 95.506(4)°; Pr₃ONSe₂: a = 2462.72(14), b = 403.74(3), c = 947.26(6) pm, β = 95.731(4)°; Nd₃ONSe₂: a = 2440.35(14), b = 401.48(3), c = 944.02(6) pm, β = 95.763(4)°). Five crystallographically different M³⁺ cations reside in six‐ to eightfold coordination of the respective anions (three independent O^2?/N^3? and Se^2? each), for which a statistic distribution of the light elements (O^2? : N^3? = 1 : 1) has to be assumed. However, the main features of the crystal structure are (O^2?/N^3?)‐centred (M³⁺)₄ tetrahedra. For the first time ever within the same structure of this kind, condensation of these anion‐centred cation polyhedra forming strands and layers simultaneously could be detected. Cis‐edge connected [(O/N)M₄]^9.5+ tetrahedra build up the chain components running along [010], which are already known as dominating core in some crystal structures of pure nitride chalcogenides (e.g. Sm₄N₂S₃ and Tb₄N₂Se₃). A new motif of condensed tetrahedral units comprises the second feature. By fusing [(O/N)M₄]^9.5+ tetrahedra via vertices and edges, one‐dimensional strand sections from the cationic sheets of the Ce₂O₂S‐type structure, which are further connected only via common vertices to form a lower‐condensed steplike two‐dimensional layer , spreading parallel to the (100) plane, emerge for the very first time.     

La3OCl[AsO3]2: Ein Lanthan‐Oxidchlorid‐Oxoarsenat(III) mit “lone‐pair”‐Kanalstruktur

La₃OCl[AsO₃]₂: A Lanthanum Oxide Chloride Oxoarsenate(III) with a “Lone‐Pair” Channel Structure La₃OCl[AsO₃]₂ was prepared by the solid‐state reaction between La₂O₃ and As₂O₃ using LaCl₃ and CsCl as fluxing agents in evacuated silica ampoules at 850 °C. The colourless crystals with pillar‐shaped habit crystallize tetragonally (a = 1299.96(9), c = 558.37(5) pm, c/a = 0.430) in the space group P4₂/mnm (no. 136) with four formula units per unit cell. The crystal structure contains two crystallographically different La³⁺ cations. (La1)³⁺ is coordinated by six oxygen atoms and two chloride anions in the shape of a bicapped trigonal prism (CN = 8), whereas (La2)³⁺ carries eight oxygen atoms and one Cl^? anion arranged in the shape of tricapped trigonal prism (CN = 9). The isolated pyramidal [AsO₃]^3? anions (d(As–O) = 175–179 pm) consist of three oxygen atoms (O2 and two O3), which surround the As³⁺ cations together with the free, non‐binding electron pair (lone pair) Ψ¹‐tetrahedrally (?(O–As–O) = 95°, 3×). One of the three crystallographically independent oxygen atoms (O1), however, is exclusively coordinated by four (La2)³⁺ cations in the shape of a real tetrahedron (d(O–La) = 236 pm, 4×). These [(O1)(La2)₄]¹⁰⁺ tetrahedra form endless chains in the direction of the c axis through trans‐edge condensation. Empty channels, constituted by the lone‐pair electrons of the Cl^? anions and the As³⁺ cations in the Ψ¹‐tetrahedral oxoarsenate(III) anions [AsO₃]^3?, run parallel to [001] as well.     

Copper scandium zirconium phosphate: occupancy of the M1 and M2 sites in the temperature range 100–300 K

The title compound, with nominal formula Cu₂ScZr(PO₄)₃, has a beige coloration and displays fast Cu⁺ cation conduction at elevated temperatures. It adopts a NASICON‐type structure in the space group Rc. The examined crystal was an obverse–reverse twin with approximately equal twin components. The [Sc^IIIZr^IV(PO₄)₃]²⁻ framework is composed of corner‐sharing Sc/ZrO₆ octahedra and PO₄ tetrahedra. The Sc and Zr atoms are disordered on one atomic site on a crystallographic threefold axis. The P atom of the phosphate group lies on a crystallographic twofold axis. Nonframework Cu⁺ cations occupy three positions. Two of the Cu⁺ positions generate an approximately circular distribution around a site of symmetry, referred to as the M1 site in the NASICON‐type structure. The other Cu⁺ position is situated close to the twofold symmetric M2 site, displaced into a position with a distorted square‐based pyramidal coordination geometry. The structure has been determined at 100, 200 and 300 K. Changes in the refined site‐occupancy factors of the Cu⁺ positions suggest increased mobility of Cu⁺ around the circular orbit close to the M1 site at room temperature, but no movement into or out of the M2 site. Free refinement of the Cu site‐occupancy factors suggests that the formula of the crystal is Cu_1.92(1)ScZr(PO₄)₃, which is consistent with the low‐level presence of Cu²⁺ exclusively in the M2 site.     

Two Hexagonal Series of Lanthanoid(III) Oxide Fluoride Selenides: M6O2F8Se3 (M = La – Nd) and M2OF2Se (M = Nd,Sm, Gd – Ho)

Two hexagonal series of lanthanoid(III) oxide fluoride selenides with similar structure types can be obtained by the reaction of the components MF₃, M₂O₃, M, and Se in sealed niobium tubes at 850 °C using CsI as fluxing agent. The compounds with the lighter and larger representatives (M = La – Nd) occur with the formula M₆O₂F₈Se₃, whereas with the heavier and smaller ones (M = Nd, Sm, Gd – Ho) their composition is M₂OF₂Se. For both systems single‐crystal determinations were used in all cases. The compounds crystallize in the hexagonal crystal system (space group: P6₃/m) with lattice parameters of a = 1394–1331 pm and c = 403–372 pm (Z = 2 for M₆O₂F₈Se₃ and Z = 6 for M₂OF₂Se). The (M1)³⁺ cations show different square antiprismatic coordination spheres with or without an extra capping fluoride anion. All (M2)³⁺ cations exhibit a ninefold coordination environment shaped as tricapped trigonal prism. In both structure types the Se^2– anions are sixfold coordinated as trigonal prisms of M³⁺ cations, being first condensed by edges to generate trimeric units and then via faces to form strands running along [001]. The light anions reside either in threefold triangular or in fourfold tetrahedral cationic coordination. For charge compensation, both structures have to contain a certain amount of oxide besides fluoride anions. Since F^– and O^2– can not be distinguished by X‐ray diffraction, bond‐valence calculations were used to address the problem of their adjunction to the available crystallographic sites.     

Poly[tetrasodium(I)‐tetra‐μ2‐bis(butane‐1,4‐diyldioxy)borato‐μ2‐1,4‐butane­diol]

In the title compound, [Na₄(C₈H₁₆BO₄)₄(C₄H₁₀O₂)]_n, there are two coordination types for the four independent Na⁺ cations: two Na⁺ cations bond to six diolate O atoms [Na—O = 2.305 (2)–2.609 (2) Å], while the other two are five‐coordinate via one 1,4‐butane­diol [2.289 (2) and 2.349 (3) Å] and four diolate O atoms [2.295 (2)–2.408 (2) Å]. Corresponding to this, there are three‐ and four‐coordinate diolate O atoms, the latter bridging Na atoms. The 1,4‐butane­diol mol­ecules lie on inversion centres. The boron stereochemistry shows minor local perturbations from its usual tetrahedral state [B—O = 1.457 (4)–1.503 (4) Å]. The resulting polymer packs as sheets parallel to the (10) plane crosslinked by the butane­diol mol­ecules. The structure was solved using data from a multiple crystal.     

The rich crystal chemistry of the AMM′(PO4)2 morphotropic series: NaZnAl(PO4)2, the first Na representative with a new structure type

A novel phosphate, sodium zinc aluminium bis(phosphate), NaZnAl(PO₄)₂, was obtained under mild‐temperature hydrothermal conditions at 553 K. The crystal structure has been studied using single‐crystal X‐ray experimental data. The pseudo‐hexagonal phase NaZnAl(PO₄)₂ crystallizes in the monoclinic space group P2₁/c. Its unique crystal structure is based on a three‐dimensional (3D) framework built by Zn‐, Al‐ and P‐centred tetrahedra sharing vertices. Channels parallel to the [101] and [01] directions are limited by six‐ and eight‐membered windows, and incorporate Na atoms. The new compound is discussed as a member of the morphotropic series AMM′PO₄, where A = Na, K, Rb or NH₄, M = Cu, Ni, Co, Fe, Zn or Mg and M′ = Fe, Al or Ga. The title compound is the first Na representative within the series and is characterized by a 3D architecture of tetrahedra populated in an ordered manner by Zn²⁺, Al³⁺ and P⁵⁺ ions.     

Dimethylhydroxyoxosulfonium(VI) Hexafluoridometallates, [(CH3)2SO(OX)]+[MF6]–(X = H,D; M = As,Sb)

Dimethylsulfone reacts in the binary superacidic systems XF/MF₅ (X = H, D; M = As, Sb) under the formation of the corresponding salts of the type [(CH₃)₂SO(OX)]⁺[MF₆]^–. The salts are characterized by low temperature vibrational spectroscopy. In case of [(CH₃)₂SO(OH)]⁺[SbF₆]^– a single‐crystal X‐ray structure analysis is reported. The salt crystallizes in the orthorhombic space group Pbca with eight formula units per unit cell [a = 10.3281(3) Å, b = 12.2111(4) Å, c = 13.9593(4) Å]. The experimental results are discussed together with quantum chemical calculations on the PBE1PBE/6‐311G++(3pd,3df) level of theory.     

The [Au(CH3SO3)4]– Anion in the Crystal Structures of M[Au(CH3SO3)4] (M = Li,Na, Rb)

The reactions of Au(OH)₃, M₂CO₃ (M = Li, Na, Rb), and methanesulfonic acid at elevated temperatures in sealed glass ampoules lead to single crystals of M[Au(CH₃SO₃)₄] (M = Li, Na, Rb). In the crystal structures of Li[Au(CH₃SO₃)₄] (tetragonal, I$\bar{4}$ , Z = 2,a = 938.64(2) pm, c = 917.01(3) pm, V = 807.93(4) ų) and Rb[Au(CH₃SO₃)₄] (tetragonal, P$\bar{4}$ 2₁c, Z = 2, a = 946.7(1) pm,c = 889.9(1) pm, V = 797.6(2) ų) the complex aurate anions are linked by the M⁺ ions in three dimensions. Contrastingly, in the structure of Na[Au(CH₃SO₃)₄] (triclinic, P$\bar{4}$ , Z = 1, a = 540.04(2) pm,b = 863.75(2) pm, c = 973.29(3) pm, α = 72.694(2)°, β = 75.605(2)°, γ = 77.687(2)°, V = 415.05(2) ų) the complex anions are connected into layers that are further connected by weak hydrogen bonds. The thermal decomposition of Li[Au(CH₃SO₃)₄] was monitored up to 500 °C and leads in a multi‐step process to elemental gold and Li₂SO₄.     

Cobalt(II) and cadmium(II) square grids supported with 4,4′‐bipyrazole and accommodating 3‐carboxyadamantane‐1‐carboxylate

In poly[[bis(μ‐4,4′‐bi‐1H‐pyrazole‐κ²N²:N^2′)bis(3‐carboxyadamantane‐1‐carboxylato‐κO¹)cobalt(II)] dihydrate], {[Co(C₁₂H₁₅O₄)₂(C₆H₆N₄)₂]·2H₂O}_n, (I), the Co²⁺ cation lies on an inversion centre and the 4,4′‐bipyrazole (4,4′‐bpz) ligands are also situated across centres of inversion. In its non‐isomorphous cadmium analogue, {[Cd(C₁₂H₁₅O₄)₂(C₆H₆N₄)₂]·2H₂O}_n, (II), the Cd²⁺ cation lies on a twofold axis. In both compounds, the metal cations adopt an octahedral coordination, with four pyrazole N atoms in the equatorial plane [Co—N = 2.156 (2) and 2.162 (2) Å; Cd—N = 2.298 (2) and 2.321 (2) Å] and two axial carboxylate O atoms [Co—O = 2.1547 (18) Å and Cd—O = 2.347 (2) Å]. In both structures, interligand hydrogen bonding [N...O = 2.682 (3)–2.819 (3) Å] is essential for stabilization of the MN₄O₂ environment with its unusually high (for bulky adamantanecarboxylates) number of coordinated N‐donor co‐ligands. The compounds adopt two‐dimensional coordination connectivities and exist as square‐grid [M(4,4′‐bpz)₂]_n networks accommodating monodentate carboxylate ligands. The interlayer linkage is provided by hydrogen bonds from the carboxylic acid groups via the solvent water molecules [O...O = 2.565 (3) and 2.616 (3) Å] to the carboxylate groups in the next layer [O...O = 2.717 (3)–2.841 (3) Å], thereby extending the structures in the third dimension.     

Two Modifications of (TeO)(HAsO4) and its Dehydration Product (Te3O3)(AsO4)2 – Three more Examples of Tellurium(IV) with a Fivefold Oxygen Coordination

Two modifications of (TeO)(HAsO₄) were obtained by reacting tellurium dioxide with arsenic acid under boiling conditions (modification I, acid concentration 80 wt‐%) or under hydrothermal conditions (modification II, acid concentration 50 wt‐%). The crystal structures of the two modifications were determined from single‐crystal X‐ray data [modification I: P2₁/c, Z = 4, a = 7.4076(10), b = 5.9596(7), c = 9.5523(11) Å, β = 102.589(8)°, 2893 structure factors, 68 parameters, R[F² > 2σ(F²)] = 0.0247, wR₂(F² all) = 0.0530; modification II: P2₁/c, Z = 4, a = 6.2962(4), b = 4.7041(3), c = 13.9446(8) Å, β = 94.528(3)°, 2549 structure factors, 69 parameters, R[F² > 2σ(F²)] = 0.0207, wR₂(F² all) = 0.0462)]. Dehydration of (TeO)(HAsO₄)‐II at temperatures above 260 °C results in the formation of polycrystalline (Te₃O₃)(AsO₄)₂. Single crystals of the anhydrous product were grown either by heating stoichiometric amounts of the binary oxides TeO₂ and As₂O₅ in closed silica glass ampoules or with higher concentrated arsenic acid (80 wt‐%) under hydrothermal conditions at 220 °C. The common features in the crystal structures of (Te₃O₃)(AsO₄)₂ [P$\bar{1}$ , Z = 4, a = 6.5548(4), b = 7.6281(6), c = 15.0464(15) Å, α = 140.212(6), β = 102.418(9)°, γ = 77.346(5)°, 5718 structure factors, 146 parameters, R[F² > 2σ(F²)] = 0.0351, wR₂(F² all) = 0. 1093] and in that of the two modifications of acidic (TeO)(HAsO₄) are [TeO₅] square‐pyramids and [AsO₄] tetrahedra. In anhydrous (Te₃O₃)(AsO₄)₂ and in (TeO)(HAsO₄)‐II, a layered arrangement of the building units is found, whereas in the (TeO)(HAsO₄)‐I structure strands are formed. Different hydrogen bonding interactions are present in the two modifications of (TeO)(HAsO₄).     

Kristallzucht und Strukturverfeinerung von Quecksilber(II)‐amidchlorid – HgClNH2

Crystal Growth and Refinement of the Crystal Structure of Mercury(II) Amide Chloride – HgClNH₂ Single crystals were prepared by recrystallization of HgClNH₂ from aqueous NH₃/NH₄⁺ solution at 160 °C. They were used for a single‐crystal X‐ray structure redetermination. The previously reported [W. N. Lipscomb, Acta. Crystallogr. 1951 , 4, 266.] structural topology determined on basis of X‐ray powder diffraction data is now confirmed. However, a higher symmetry is found: Space group type Pmma (instead of Pmm2), a = 6.709(1) Å, b = 4.351(1) Å, c = 5.154(1) Å, Z = 2. The crystal structure contains zig‐zag‐chains [Hg(NH₂)_2/2]⁺. Four Cl atoms complete the coordination sphere of Hg to a distorted octahedron. These share common faces and edges in layers [HgCl_4/4(NH₂)_2/2]. These layers are connected via hydrogen bonds N–H…Cl.     

An arsenate with the α‐CrPO4 structure type,NaCa1–xNi3–2xAl2x(AsO4)3 (x = 0.23): crystal structure,charge‐distribution and bond‐valence‐sum analyses

Since the discovery of electrochemically active LiFePO₄, materials with tunnel and layered structures built up of transition metals and polyanions have become the subject of much research. A new quaternary arsenate, sodium calcium trinickel aluminium triarsenate, NaCa_1–x Ni_3–2x Al_2x (AsO₄)₃ (x = 0.23), was synthesized using the flux method in air at 1023 K and its crystal structure was determined from single‐crystal X‐ray diffraction (XRD) data. This material was also characterized by qualitative energy‐dispersive X‐ray spectroscopy (EDS) analysis and IR spectroscopy. The crystal structure belongs to the α‐CrPO₄ type with the space group Imma . The structure is described as a three‐dimensional framework built up of corner‐edge‐sharing NiO₆, (Ni,Al)O₆ and AsO₄ polyhedra, with channels running along the [100] and [010] directions, in which the sodium and calcium cations are located. The proposed structural model has been validated by bond‐valence‐sum (BVS) and charge‐distribution (CHARDI) tools. The sodium ionic conduction pathways in the anionic framework were investigated by means of the bond‐valence site energy (BVSE) model, which predicted that the studied material will probably be a very poor Na⁺ ion conductor (bond‐valence activation energy ∼7 eV).     

Univalent Gallium and Indium Phosphane Complexes: From Pyramidal M(PPh3)3+ to Carbene‐Analogous Bent M(PtBu3)2+ (M=Ga,In) Complexes

In a new oxidative route, Ag⁺[Al(OR^F)₄]^? (R^F=C(CF₃)₃) and metallic indium were sonicated in aromatic solvents, such as fluorobenzene (PhF), to give a precipitate of silver metal and highly soluble [In(PhF)_n]⁺ salts (n=2, 3) with the weakly coordinating [Al(OR^F)₄]^? anion in quantitative yield. The In⁺ salt and the known analogous Ga⁺[Al(OR^F)₄]^? were used to synthesize a series of homoleptic PR₃ phosphane complexes [M(PR₃)_n]⁺, that is, the weakly PPh₃‐bridged [(Ph₃P)₃In–(PPh₃)–In(PPh₃)₃]²⁺ that essentially contains two independent [In(PPh₃)₃]⁺ cations or, with increasing bulk of the phosphane, the carbene‐analogous [M(PtBu₃)₂]⁺ (M=Ga, In) cations. The M^I? P distances are 27 to 29 pm longer for indium, and thus considerably longer than the difference between their tabulated radii (18 pm). The structure, formation, and frontier orbitals of these complexes were investigated by calculations at the BP86/SV(P), B3LYP/def2‐TZVPP, MP2/def2‐TZVPP, and SCS‐MP2/def2‐TZVPP levels.     

Synthesis,Crystal Structure,Vibrational Spectra,and Thermal Behaviour of [Ph4P]2[Bi2(μ‐Br)2Br6 (CH3COCH3)2]

[Ph₄P]₂[Bi₂Br₈(CH₃COCH₃)₂] ( 1 ) was obtained by the reaction of [Ph₄P]Br and BiBr₃ in acetone. Single crystals were grown by allowing a layer of n‐hexane to diffuse into the acetonic solution of 1 . The crystal structure was determined by means of X‐ray diffraction. 1 crystallises with monoclinic symmetry in the space group P2₁/n, No. 14 with the lattice parameters: a = 13.358(2), b = 12.637(2), c = 18.565(3) Å, β = 102.62(1)°, V = 3058.1(8) ų and Z = 4. The structure is characterised by the anion [Bi₂Br₈(CH₃COCH₃)₂]^2– which is embedded in a matrix of [Ph₄P]⁺ cations. The anion can be described as two edge‐sharing square pyramids with the apical bromide ions in anti‐position. Acetone co‐ordinates the bismuth atoms via oxygen atoms and increases the co‐ordination number of central bismuth atoms to six which results in the formation of a distorted bi‐octahedron. The distortion is due to the difference in terminal and bridging Bi–Br bond lengths. FT‐IR and Raman spectroscopic data are presented. In addition, the thermal behaviour of the compound was studied with the aid of TG/DSC coupled with MS revealing that acetone leaves the crystal in two steps. The compound melts at 203 °C and transforms into a glass on cooling.