Bi53+‐Polykationen in geordneten und plastischen Kristallen von Bi5[AlI4]3 und Bi5[AlBr4]3

Bi₅³⁺ Polycations in Ordered and Plastic Crystals of Bi₅[AlI₄]₃ and Bi₅[AlBr₄]₃ Dark‐red air‐sensitive crystals of pentabismuth‐tris(tetrabromoaluminate) Bi₅[AlBr₄]₃ and black crystals of Bi₅[AlI₄]₃ have been crystallized from melts of Bi, BiX₃ and AlX₃ (X = Br, I). X‐ray diffraction on a single crystal of Bi₅[AlI₄]₃ (T = 293(2) K; space group Pnma; a = 2143.6(3) pm, b = 1889.1(1) pm, c = 811.74(5) pm) revealed an ordered packing of Bi₅³⁺ trigonal bipyramids and [AlI₄]^? tetrahedra that corresponds to the PuBr₃ structure type. Contrary to the so far known Bi₅³⁺ polycations with accurate D_3h symmetry, the bismuth cluster found in Bi₅[AlI₄]₃ holds only C_s symmetry. The room temperature structure of the tetrabromoaluminate Bi₅[AlBr₄]₃, which is related to the AuCu₃ type, shows a dynamic disorder of the Bi₅³⁺ polycations (T = 293(2) K; space group ; a = 1766.2(3) pm). Slight cooling induces the transition into an ordered rhombohedral phase isostructural to Bi₅[AlCl₄]₃ (T = 260(2) K; space group a = 1241.5(8) pm, c = 3041(2) pm).     

Synthesen,Kristallstrukturen und Drillingsbildung der Cluster‐Trimere Bi2[PtBi6Br12]3 und Bi2[PtBi6I12]3

Syntheses, Crystal Structures, and Triple Twinning of the Cluster Trimers Bi₂[PtBi₆Br₁₂]₃ and Bi₂[PtBi₆I₁₂]₃ Melting reactions of Bi with Pt and BiX₃ (X = Br, I) yield shiny black, air insensitive crystals of the subhalides Bi₂[PtBi₆X₁₂]. Bi₂[PtBi₆Br₁₂]₃ crystallizes in the monoclinic space group C2/m with lattice parameters a = 1617.6(2) pm, b = 1488.5(1) pm, c = 1752.4(2) pm, and β = 110.85(4)°. Bi₂[PtBi₆I₁₂]₃ adopts the triclinic space group with pseudo‐monoclinic lattice parameters a = 1711.2(2) pm, b = 1585.1(1) pm, c = 1865.7(2) pm, and α = 90°, β = 111.15(4)°, γ = 90°. The two homoeotypic compounds consist of cuboctahedral [Pt^?IIBi^II₆X^?I₁₂]^2? clusters that are concatenated into linear trimers by Bi^III atoms. The ordered distribution of Bi^III atoms destroys the inherent threefold rotation axes in the packing of cluster anions. As a consequence of the pseudosymmetry the crystals are triple twinned along [201]. Due to different orientations of the cluster trimers there are two Bi^II···X inter‐cluster bridges per Bi^II atom in Bi₂[PtBi₆Br₁₂]₃ but only one bridge in Bi₂[PtBi₆I₁₂]₃. The structure of the iodine compound can be deduced from the NaCl structure type, leaving 37 of 96 atomic positions unoccupied. The arrangement of the cuboctahedral clusters follows the motif of a body‐centered cubic packing.     

[Ru2Bi14Br4](AlCl4)4 by Mobilization and Reorganization of Complex Clusters in Ionic Liquids

Two polymorphs of the new cluster compound [Ru₂Bi₁₄Br₄](AlCl₄)₄ have been synthesized from Bi₂₄Ru₃Br₂₀ in the Lewis acidic ionic liquid [BMIM]Cl/AlCl₃ ([BMIM]⁺: 1‐n‐butyl‐3‐methylimidazolium) at 140 °C. A large fragment of the precursor’s structure, namely the [(Bi₈)Ru(Bi₄Br₄)Ru(Bi₅)]⁵⁺ cluster, dissolved as a whole and transformed into a closely related symmetrical [(Bi₅)Ru(Bi₄Br₄)Ru(Bi₅)]⁴⁺ cluster through structural conversion of a coordinating Bi₈²⁺ to a Bi₅⁺ polycation, while the remainder was left intact. Both modifications have monoclinic unit cells that comprise two formula units (α form: P2₁/n, a=982.8(2), b=1793.2(4), c=1472.0(3) pm, β=109.05(3)°; β form: P2₁/n, a=1163.8(2), b=1442.7(3), c=1500.7(3), β=97.73(3)°). The [Ru₂Bi₁₄Br₄]⁴⁺ cluster can be regarded as a binuclear inorganic complex of two ruthenium(I) cations that are coordinated by terminal Bi₅⁺ square pyramids and a central Bi₄Br₄ ring. The presence of a covalent Ru? Ru bond was established by molecular quantum chemical calculations utilizing real‐space bonding indicator ELI‐D. Structural similarity of the new and parent cluster suggests a structural reorganization or an exchange of the bismuth polycations as mechanisms of cluster formation. In this top‐down approach a complex‐structured unit formed at high temperature was made available for low‐temperature use.     

Die Cluster‐Salze Bi14Si2MI12 (M = Rh,Ir): [Bi8Si2]‐ und [MBi6I12]‐Baugruppen in CsCl‐analoger Anordnung

The Cluster Salts Bi₁₄Si₂MI₁₂ (M = Rh, Ir): [Bi₈Si₂] and [MBi₆I₁₂] Building Groups in CsCl‐like Structure The reaction of bismuth and iridium with iodine in evacuated quartz ampoules at 1320 K yields black, air insensitive crystals of Bi₁₄Si₂IrI₁₂. The silicon therein is abstracted from the ampoule material whereby the oxygen is gettered in BiOI. The synthesis of Bi₁₄Si₂RhI₁₂ requires the addition of niobium, which gives NbOI₂ with the oxygen originating from the SiO₂. X‐ray diffraction on single crystals showed that the two isotypic compounds crystallize in the space groups P 4/m c c with a = 1018.3(1), c = 2020.1(4) pm for M = Ir, and a = 1019.0(1), c = 2018.7(4) pm for M = Rh. The crystal structures consist of two types of isolated clusters, which form a CsCl‐like packing. In the [MBi₆I₁₂] cuboctahedron the central transition metal atom is octahedrally surrounded by bismuth atoms, and the iodine atoms bridge the edges of the octahedron. The [Bi₈Si₂] polyhedron is a tetragonal antiprism of bismuth atoms of which square faces are capped by silicon atoms. Based on crystal chemistry and band structure calculations the compounds may be formulated as cluster salts [Bi₈Si₂]³⁺[MBi₆I₁₂]^3–. Measurements of the electrical conductivity showed that Bi₁₄Si₂IrI₁₂ is a semiconductor with a band gap of about 0.1 eV. A single unpaired electron out of 1903 electrons per formula causes paramagnetic behaviour that is superposed by strong diamagnetic contributions.     

Synthesen,Eigenschaften und Kristallstrukturen der Cluster‐Salze Bi6[PtBi6Cl12] und Bi2/3[PtBi6Cl12]

Syntheses, Properties and Crystal Structures of the Cluster Salts Bi₆[PtBi₆Cl₁₂] and Bi_2/3[PtBi₆Cl₁₂] Melting reactions of Bi with Pt and BiCl₃ yield shiny black, air insensitive crystals of the subchlorides Bi₆[PtBi₆Cl₁₂] and Bi_2/3[PtBi₆Cl₁₂]. Despite the substantial difference in the bismuth content the two compounds have almost the same pseudo‐cubic unit cell and follow the structural principle of a CsCl type cluster salt. Bi₆[PtBi₆Cl₁₂] consists of cuboctahedral [PtBi₆Cl₁₂]^2? clusters and Bi₆²⁺ polycations (a = 9.052(2) Å, α = 89.88(2)°, space group P 1, multiple twins). In the electron precise cluster anion, the Pt atom (18 electron count) centers an octahedron of Bi atoms whose edges are bridged by chlorine atoms. The Bi₆²⁺ cation, a nido cluster with 16 skeletal electrons, has the shape of a distorted octahedron with an opened edge. In Bi_2/3[PtBi₆Cl₁₂] the anion charge is compensated by weakly coordinating Bi³⁺ cations which are distributed statistically over two crystallographic positions (a = 9.048(2) Å, α = 90.44(3)°, space group ). Bi₆[PtBi₆Cl₁₂] is a semiconductor with a band gap of about 0.1 eV. The compound is diamagnetic at room temperature though a small paramagnetic contribution appears towards lower temperature.     

Metal Assisted Synthesis of Cationic Sulfidobismuth Cubanes in Ionic Liquids

Bi₂S₃ was dissolved in the presence of either AuCl/PtCl₂ or AgCl in the ionic liquids [BMIm]Cl ⋅ xAlCl₃ (BMIm=1-n-butyl-3-methylimidazolium; x=4–4.3) through annealing the mixtures at 180 or 200 °C. Upon cooling to room temperature, orange, air-sensitive crystals of [BMIm](Bi₄S₄)[AlCl₄]₅ ( 1 ) or Ag(Bi₇S₈)[S(AlCl₃)₃]₂[AlCl₄]₂ ( 2 ) precipitated, respectively. 1 did not form in the absence of AuCl/PtCl₂, suggesting an essential role of the metal cations. X-ray diffraction on single-crystals of 1 revealed a monoclinic crystal structure that contains (Bi₄S₄)⁴⁺ heterocubanes and [AlCl₄]⁻ tetrahedra as well as [BMIm]⁺ cations. The intercalation of the ionic liquid was confirmed via solid state NMR spectroscopy, revealing unusual coupling behavior. The crystal structure of 2 consists of (Bi₇S₈)⁵⁺ spiro-dicubanes, [S(AlCl₃)₃]²⁻ tetrahedra triples, isolated [AlCl₄]⁻ tetrahedra, and heavily disordered silver(I) cations. No cation ordering took place in 2 upon slow cooling to 100 K.     

Selen‐Polykationen stabilisiert durch polymere Chlorobismutat‐Anionen: Synthesen und Kristallstrukturen von Se4[Bi4Cl14] und Se10[Bi5Cl17]

Selenium Polycations Stabilized by Polymeric Chlorobismuthate Anions: Syntheses and Crystal Structures of Se₄[Bi₄Cl₁₄] and Se₁₀[Bi₅Cl₁₇] Reactions of selenium with selenium(IV) chloride and bismuth(III) chloride in sealed evacuated glass ampoules at temperatures between 110 and 155 °C yield a series of compounds which are composed of discrete selenium polycations and polymeric chlorobismutate anions. Besides the already known Se₈[Bi₄Cl₁₄] two new compounds have been identified by crystal structure analyses as Se₄[Bi₄Cl₁₄] (tetragonal, P4/n, a = 1089.1(2) pm, c = 993.7(2) pm, Z = 2) and Se₁₀[Bi₅Cl₁₇] (monoclinic, P2₁/c, a = 1079.24(8) pm, b = 2062.9(2) pm, c = 1676.1(2) pm, β = 90.87(1)°, Z = 4). Se₄[Bi₄Cl₁₄] was obtained as red transparent platelike crystals and is the first example of a compound with (chalcogen₄)²⁺ ions of exact square‐planar symmetry and molecular point group D_4h in the solid state. The cations are surrounded by layers of two‐dimensional polymeric anions [Bi₄Cl₁₄]^2–. Se₁₀[Bi₅Cl₁₇] forms dark grey crystals with a reddish luster. The structure contains the known bicyclic polycation Se₁₀²⁺ which is disordered over two positions and the first three‐dimensional polymeric chlorobismutate anion [Bi₅Cl₁₇]^2–. The different BiCl_x polyhedra are linked by sharing common vertices, edges, and faces.     

Between Localization and Delocalization: Ru(cod)2+ Units in the Zintl Clusters [Bi9{Ru(cod)}2]3− and [Tl2Bi6{Ru(cod)}]2−

Reactions of [K(crypt‐222)]₂(TlBi₃)⋅0.5 en ( 1 b ) with [Ru(cod)(H₂CC(Me)CH₂)₂] ( A ) in 1,2‐diaminoethane (en) led to the formation of two compounds with new bismuth‐rich cluster anions, [K(crypt‐222)]₃[Bi₉{Ru(cod)}₂]⋅1.5 en ( 2 ) and [K(crypt‐222)]₂[Tl₂Bi₆{Ru(cod)}]⋅2 tol ( 3 ), alongside the salt of a binary nido cluster, [K(crypt‐222)]₃(Tl₄Bi₅)⋅2 en ( 4 ). The anions in 2 and 3 are two further examples of rare heterometallic clusters containing Ru atoms. As one cod ligand is retained on each Ru atom in both clusters, the anions may be viewed as intermediates on the way towards larger, ligand‐free intermetalloid clusters. Quantum‐chemical studies provided insight into the bonding situation in these clusters. According to these studies, the anion of 2 features both electron‐precise and electron‐deficient parts. Electrospray ionization mass spectrometry analysis indicated that the clusters undergo stepwise fragmentation.     

Bi37InBr48: Eine polares Subhalogenid mit Bi95+‐Polykationen,komplexen Bromobismutat(III)‐Anionen [Bi3Br13]4— und [Bi7Br30]9— sowie Pentabromoindat(III)‐Anionen [InBr5]2—

Bi₃₇InBr₄₈: a Polar Subhalide with Bi₉⁵⁺ Polycations, Complex Bromobismuthate(III) Anions [Bi₃Br₁₃]^4— and [Bi₇Br₃₀]^9—, and Pentabromoindate(III) Anions [InBr₅]^2— Black crystals of Bi₃₇InBr₄₈ were synthesized from bismuth, indium and BiBr₃ by cooling stoichiometric melts from 570 K to 470 K. X‐ray diffraction on powders and single‐crystals revealed that the compound crystallizes with space group P 6₃ (a = 2262.6(4); c = 1305.6(2) pm). The Bi₉⁵⁺ polycations in the polar crystal structure have the shape of heavily distorted tri‐capped trigonal prisms with approximate C_s symmetry. The high complexity of the structure results from three coexisting types of anionic groups: Three edge‐sharing [BiBr₆] octahedra constitute the trigonal bromobismuthate(III) anion [Bi₃Br₁₃]^4—. Four [BiBr₆] and three [BiBr₅] polyhedra share common vertices to form the [Bi₇Br₃₀]^9— hemi‐sphere, in which the trigonal bipyramid of the pentabromoindat(III) ion [InBr₅]^2— is embedded.     

Origin and Location of Electrons and Protons during the Formation of Intermetalloid Clusters [Sm@Ga3−xH3−2xBi10+x]3− (x=0, 1)

Reaction of [GaBi₃]^2? with [Sm(C₅Me₄H)₃] yielded the first protonated ternary intermetalloid clusters [Sm@Ga_3?xH_3?2xBi_10+x]^3? ( 1 ; x=0,1). The presence of the Ga? H bonds and the transfer of electrons and protons during the formation of 1 were elucidated by a combination of experimental and quantum chemical methods, thereby rationalizing the role of the solvent ethane‐1,2‐diamine as a Brønsted acid. As an organic by‐product, we observed the previously unknown octamethylfulvene ( 2 ) upon C? C coupling of (C₅Me₄H)^?.     

Ionic‐Radius‐Driven Selection of the Main‐Group‐Metal Cage for Intermetalloid Clusters [Ln@PbxBi14−x]q− and [Ln@PbyBi13−y]q− (x/q=7/4, 6/3; y/q=4/4, 3/3)

Reactions of the binary, pseudo‐homoatomic Zintl anion (Pb₂Bi₂)^2? with Ln(C₅Me₄H)₃ (Ln=La, Ce, Nd, Gd, Sm, Tb) in the presence of [2.2.2]crypt in ethane‐1,2‐diamine/toluene yielded ten [K([2.2.2]crypt)]⁺ salts of lanthanide‐doped semimetal clusters with 13 or 14 surface atoms. Single‐crystal X‐ray diffraction and energy‐dispersive X‐ray spectroscopy indicated the presence of the anions [Ln@Pb₆Bi₈]^3?, [Ln@Pb₃Bi₁₀]^3?, [Ln@Pb₇Bi₇]^4?, or [Ln@Pb₄Bi₉]^4? in single or double salts; the latter showed various ratios of the components in the solid state. The anions are the first ternary intermetalloid clusters comprising only elements of the sixth period of the periodic table, namely, Pb, Bi and lanthanides. This study, which was complemented by ESI mass spectrometry and ¹³⁹La NMR spectroscopy in solution, rationalizes a continuous development of the ratio of 13:14‐atom cages with the ionic radius of the embedded Ln³⁺ ion, which seems to select the most suitable cage type. Quantum chemical investigations helped to analyze this situation in more detail and to explain the observed subtle influence of the atomic radii. Magnetic measurements confirmed that the embedded Ln³⁺ ions keep their expected paramagnetic or diamagnetic nature.     

Bi12,86Ni4Br6 und Bi12,86Ni4I6: Subhalogenide mit intermetallischen und salzartigen Schichtpaketen in alternierender Abfolge

Bi_12.86Ni₄Br₆ and Bi_12.86Ni₄I₆: Subhalides with Alternating Intermetallic and Salt‐like Layers The reaction of bismuth and nickel with bromine or iodine at 730 K yields black, air insensitive, needle shaped crystals of the ternary subhalides Bi_12.86Ni₄X₆ (X = Br, I). The isotypic compounds crystallize in the orthorhombic space groups Immm with a = 405.69(6) pm, b = 874.00(8) pm, c = 3744.7(4) pm for X = Br, and a = 410.05(5) pm, b = 912.84(7) pm, c = 3826.7(3) pm for X = I. The crystal structures contain characteristic fragments of the intermetallic phase Bi₃Ni: chains consisting of face‐sharing mono‐capped trigonal prisms of bismuth atoms with a nickel atom in the center of each prism. The chains form corrugated layers which are separated by halogen atoms and oligomeric [Bi_nX_4n+2] units of varying length. The halogenobismutate(III) units consist of trans‐edge‐sharing [BiX₆] octahedra. They are disordered within the crystal structures. The non‐integer stoichiometric coefficients of Bi_12.86Ni₄X₆ are due to the metric adjustment between the ionic and intermetallic parts of the structure. Extended Hückel calculations indicate, that the partial oxidation of the intermetallic phase causes a strengthening of the chemical bonding within the Bi₃Ni chains. The subiodide Bi_12.86Ni₄I₆ is paramagnetic and shows ferromagnetic ordering below 25 K.     

Ag3Bi14Br21: ein Subbromid mit Bi24+‐Hanteln und Bi95+‐Polyedern – Synthese,Kristallstruktur und Chemische Bindung

Ag₃Bi₁₄Br₂₁: a Subbromide with Bi₂⁴⁺ Dumbbells and Bi₉⁵⁺ Polyhedra – Synthesis, Crystal Structure and Chemical Bonding Black crystals of Ag₃Bi₁₄Br₂₁ = (Bi₉⁵⁺)[Ag₃Bi₃Br₁₅^3?](Bi₂Br₆^2?), the first argentiferous bismuth subhalide, were obtained from a stoichiometric melt of Ag, Bi, and BiBr₃. The compound crystallizes in the monoclinic space group P2₁/m with lattice parameters a = 1277.78(5) pm, b = 1466.87(6) pm, c = 1342.62(5) pm, and β = 108.47(1)° at 110(5) K. In contrast to all other bismuth subhalides that contain an electron‐rich transition metal, the silver atoms are not bonded to bismuth atoms. Instead they are integrated into the anionic bromometallate network, which consists of [MBr₆]‐octahedra (M = Ag, Bi) that share edges and vertices. These corrugated sheets alternate with tessellated layers formed by Bi₉⁵⁺ polycations and hitherto unknown (Bi^II₂Br₆)^2? groups. The latter anions contain Bi₂⁴⁺ dumbbells (299 pm) and can be represented by the structured formula [Br₂Bi^II(μ–Br)₂Bi^IIBr₂]^2?. The multi‐center bonding within the Bi₉⁵⁺ cluster and the bent single‐bond in the Bi₂ dumbbell can be visualized using the electron localization indicator (ELI‐D).     

Synthesis and crystal structures of Cd[AlCl4]2 and Cd2[AlCl4]2

Colorless single crystals of Cd[AlCl₄]₂ grow from the melt of CdCl₂ and AlCl₃ upon slow cooling from 250°C. The crystal structure [monoclinic, P1a1, Z = 2, a = 1288.7(2), b = 660.2(1), c = 705.1(1) pm, β = 92.89(1)º] may be derived from hexagonally closest packed layers of Cl^?. Octahedral and tetrahedral holes are filled with Cd²⁺ and Al³⁺ in a 1:2 ratio between all layers stacked in the [104] direction. Cd[GaCl₄]₂ and Cd[AlBr₄]₂ are isotypic. Reduction of Cd[AlCl₄]₂ with excess cadmium shot and slow cooling from 350°C yields plate-like very moisture-sensitive, colorless single crystals of Cd₂[AlCl₄]₂. The crystal structure [triclinic, C1 , Z = 2, a = 655.47(3), b = 1135.26(1), c = 935.23(6) pm, α = 89.70(2)º, β = 103.61(1)º, γ = 90.455(1)º] is built from slabs stacked in the [100] direction consisting of ethane-like [Cd₂Cl₆] units with a Cd? Cd distance of 256.1 pm sharing common vertices with [AlCl₄] tetrahedra.     

Endohedrally Filled [Ni@Sn9]4− and [Co@Sn9]5− Clusters in the Neat Solids Na12Ni1−xSn17 and K13−xCo1−xSn17: Crystal Structure and 119Sn Solid‐State NMR Spectroscopy

A systematic approach to the formation of endohedrally filled atom clusters by a high‐temperature route instead of the more frequent multistep syntheses in solution is presented. Zintl phases Na₁₂Ni_1?xSn₁₇ and K_13?xCo_1?xSn₁₇, containing endohedrally filled intermetalloid clusters [Ni@Sn₉]^4? or [Co@Sn₉]^5? beside [Sn₄]^4?, are obtained from high‐temperature reactions. The arrangement of [Ni@Sn₉]^4? or [Co@Sn₉]^5? and [Sn₄]^4? clusters, which are present in the ratio 1:2, can be regarded as a hierarchical replacement variant of the hexagonal Laves phase MgZn₂ on the Mg and Zn positions, respectively. The alkali‐metal positions are considered for the first time in the hierarchical relationship, which leads to a comprehensive topological parallel and a better understanding of the composition of these compounds. The positions of the alkali‐metal atoms in the title compounds are related to the known inclusion of hydrogen atoms in the voids of Laves phases. The inclusion of Co atoms in the {Sn₉} cages correlates strongly with the number of K vacancies in K_13?xCo_1?xSn₁₇ and K_5?xCo_1?xSn₉, and consequently, all compounds correspond to diamagnetic valence compounds. Owing to their diamagnetism, K_13?xCo_1?xSn₁₇, and K_5?xCo_1?xSn₉, as well as the d‐block metal free binary compounds K₁₂Sn₁₇ and K₄Sn₉, were characterized for the first time by ¹¹⁹Sn solid‐state NMR spectroscopy.     

Room‐Temperature Synthesis of Bismuth Clusters in Ionic Liquids and Crystal Growth of Bi5(AlCl4)3

The viability of Lewis‐acid ionic liquids for the synthesis of low‐valent bismuth compounds is demonstrated. At room temperature, elemental bismuth and bismuth(III) cations synproportionate in the ionic liquid [BMIM]Cl/AlCl₃ ([BMIM]⁺: 1‐n‐butyl‐3‐methylimidazolium) within minutes. The existence of bismuth polycations in the dark colored solution was proven by Raman spectroscopy. Dark‐red crystals of Bi₅(AlCl₄)₃ were isolated from the ionic liquid and characterized by Raman spectroscopy and X‐ray crystallography (rhombohedral space‐group , a = 1187.1(2) pm, c = 3012.0(3) pm). The method allows the synthesis of bismuth cluster compounds under milder conditions than in high‐temperature melts and more conveniently and environmental friendly than in liquid SO₂ with strongly oxidizing, toxic agents like SbF₅ or AsF₅.     

Bi24Ru3Br20: Ein pseudo-tetragonales Subbromid mit [RuBi6Br12]-Clustern und [Ru2Bi17Br4]-Gruppen

Bi₂₄Ru₃Br₂₀: A Pseudo-Tetragonal Structure with [RuBi₆Br₁₂] Clusters and [Ru₂Bi₁₇Br₄] Groups The melting reaction of Ru with Bi and BiBr yields black, lustrous, air insensitive crystals of the subbromide Bi₂₄Ru₃Br₂₀. The orthorhombic crystal structure (space group Pc2₁n, a = b = 1377.8(1) pm, c = 3222.3(4) pm, V = 6117.0 · 10⁶ pm³) deceives pseudo-symmetry with respect to the tetragonal space group P4/ncc leading to multiply twinned crystals. The structure can formally be subdivided in [RuBi₆Br₁₂] clusters, [Ru₂Bi₁₇Br₄] stacks, and [BiBr₄] groups.     

[2+2+2] Cycloisomerisation of Aromatic Cyanodiynes in the Synthesis of Pyridohelicenes and Their Analogues

We have developed a methodology for the synthesis of pyridohelicenes and their analogues based on the Ni⁰‐, Co^I‐ or Rh^I‐mediated intramolecular [2+2+2] cycloisomerisation of cyanodiynes. It allows for folding the linear precursors into the corresponding helical backbones comprising the newly formed pyridine unit in their central part. Along with racemic pyrido[n]helicenes (n=5,6,7) and their derivatives, both enantio‐ and diastereomerically pure pyrido[n]helicene‐like molecules (n=5,6) were prepared by employing the chiral substrate‐controlled cyclisation of the corresponding enantiopure cyanodiynes.     

Ionothermal Synthesis of Sulfidobismuth spiro-Dicubane Cations

Bi₂S₃ was dissolved in the presence of NaCl in the ionic liquid [BMIm]Cl ⋅ 4AlCl₃ (BMIm=1-n-butyl-3-methylimidazolium) through annealing the mixture at 180 °C. Upon cooling to room temperature, orange, air-sensitive crystals of Na(Bi₇S₈)[S(AlCl₃)₃]₂[AlCl₄]₂ ( 1 ) precipitated. X-ray diffraction on single-crystals of 1 revealed a triclinic crystal structure that contains (Bi₇S₈)⁵⁺ spiro-dicubanes, [S(AlCl₃)₃]²⁻ tetrahedra triples, isolated [AlCl₄]⁻ tetrahedra, and sodium cations.     

[Bi4]6– – The Zintl Anion with the Highest Charge per Atom Obtained from Solution

From the dark‐purple solution of the Zintl phase KBi in liquid ammonia dark‐blue crystals of the ammonia solvate K₆[Bi₄](NH₃)₈ were obtained. In contrast to known Bi_n polyanions the chemical bond in the anion [Bi₄]^6– is in accordance with the (8‐N) rule featuring solely Bi–Bi single bonds. [Bi₄]^6– is a butane‐analog valence compound, and with 6 negative charges per 4 atoms it is the anion with the highest known charge per atom obtained from solution. The planarity of the trans‐[Bi₄]^6– unit hints at π orbital contributions of the bismuth atoms. The corresponding reactions of the phases K₅Bi₄ and K₃Bi₂ in liquid ammonia in the presence of [2.2.2]crypt(4, 7, 13, 16, 21, 24‐hexaoxa‐1, 10‐diazabicyclo‐[8.8.8]hexacosane) lead to the salt [K([2.2.2]crypt)]₂[Bi₂](NH₃)₄ with the known electron‐deficient [Bi₂]^2– polyanion and a Bi=Bi double bond.