The First Step of the Oxidation of Elemental Sulfur: Crystal Structure of the Homopolyatomic Sulfur Radical Cation [S8].+

The oxidation of elemental sulfur in superacidic solutions and melts is one of the oldest topics in inorganic main group chemistry. Thus far, only three homopolyatomic sulfur cations ([S₄]²⁺, [S₈]²⁺, and [S₁₉]²⁺) have been characterized crystallographically although ESR investigations have given evidence for the presence of at least two additional homopolyatomic sulfur radical cations in solution. Herein, the crystal structure of the hitherto unknown homopolyatomic sulfur radical cation [S₈]^.+ is presented. The radical cation [S₈]^.+ represents the first step of the oxidation of the S₈ molecule present in elemental sulfur. It has a structure similar to the known structure of [S₈]²⁺, but the transannular sulfur⋅⋅⋅sulfur contact is significantly elongated. Quantum-chemical calculations help in understanding its structure and support its presence in solution as a stable compound. The existence of [S₈]^.+ is also in accord with previous ESR investigations.     

Cross-Talks Between Sulfane Sulfur and Thiol at a Zinc(II) Site

Transformations of sulfane sulfur compounds (e. g. organic polysulfides (R−S_n−R, n>2) and elemental sulfur (S₈)) play pivotal roles in the biochemical landscape of sulfur, and thus supports signaling activities of H₂S. Although a number of previous reports illustrate amine mediated reactions of S₈ and thiol (RSH) yielding R−S_n−R, this report illustrates that a tripodal [Zn^II] complex [( Bn₃Tren )Zn^II−OH₂](ClO₄)₂ ( 1 ) facilitates the reactions of sulfane sulfur and thiol (RSH), thereby offering an amine-free biologically relevant complementary route. UV-vis monitoring of the reactions and a set of control experiments underline the definitive role of [Zn^II] coordination motif in the reactions of sulfane sulfur (e. g. S₈ and R−S_n−R) with RSH. Detailed investigations (UV-vis, NMR, ESI-MS, intermediate trapping, and TEMPO radical interference experiments) disclose the key differences in the [Zn^II] versus previously known amine mediated routes. Moreover, the persulfide (RSS⁻) trapping experiments using 1-fluoro-2,4-dinitrobenzene (F-DNB) reveal the intermediacy of RSS⁻ species in the [Zn^II] mediated reactions of sulfane sulfur and thiol, thereby demonstrating [Zn^II] assisted persulfidation of thiol in the presence of sulfane sulfur species. Of broader impact, this study underscores the feasible influence of biologically relevant [Zn^II] coordination motifs (e. g. carbonic anhydrase) on the sulfane sulfur chemistry in biology.     

Derivatives of Cyclic Inorganic Sulfur Imides

Abstract

1) Cyclic inorganic sulfur imides, S₇NH, S₆(NH)₂ 1.3 S₅(NH)₃1.3.5 and S₄(NH)₄1.3.5.7. in solution in polar solvents (acetone, acetonitrile, etc.) release the radicals S₇N-, S₆N₂ ^2- and S₅N^3- under the action of alkali. Their study by near UV spectroscopy reveals unstable radicals which rapidly pass into the more stable S₄N^- radical. The latter in turn gives, by charge transfer with the solvent (acetone), the blue complex [S₄N–OC(CH₃)₂]. Non polar solvents (CCl₄) do not give this charge transfer complex (C.T.C.).

2) The sulfur imides mentioned above react with a solution of S₈ to give, via hydrogen bonds, crystalline C.T.C's of formula [3 S₈–S₇NH.] or [2 S₈–S₆(NH)₂1.3]. X-ray examination reveals that these complexes are isotypes of the sulfurs S₈β and S ₈γ whose crystals are stabilized by intermolecular hydrogen bonds.

3) The reaction of the sulfur imides with formic aldehyde gives primary cyclic polyalcohols, such as S₅(N-CH₂OH)₃ or S₄(N-CH₂OH)₄, which form typical molecular cages through intramolecular hydrogen bonds.

4) Examination of Van der Waals bonds of the crystallized sulfur imides enables their comparison with molecules of these compounds containing other types of bonds.     

Theoretical study on interactions between thiophene/dibenzothiophene/cyclohexane/toluene and 1-methyl-3-octylimidazolium tetrafluoroborate

It is critically important to understand the interactions between thiophene/dibenzothiophene/cyclohexane/toluene and 1-methyl-3-octylimidazolium tetrafluoroborate ([C8MIM]⁺[BF₄]^?) due to desulfurization by ionic liquids. In this work, the structures of thiophene, dibenzothiophene, cyclohexane, toluene, [C8MIM]⁺[BF₄]^?, [C8MIM]⁺[BF₄]^?-thiophene, [C8MIM]⁺[BF₄]^?-dibenzothiophene, [C8MIM]⁺[BF₄]^?-cyclohexane, and [C8MIM]⁺[BF₄]^?-toluene were optimized systematically at the GGA/PW91/DNP level, and the most stable geometries were performed by NBO and AIM analyses. It was found that [BF₄]^? anion tends to locate near C2–H2 and four hydrogen bonds between [C8MIM]⁺ and [BF₄]^? form in [C8MIM]⁺[BF₄]^?. There exist hydrogen bonds and C–H···π interactions between [C8MIM]⁺[BF₄]^? and thiophene/cyclohexane/toluene, while the hydrogen bonding interactions, π···π and C–H···π interactions occur between [C8MIM]⁺[BF₄]^? and dibenzothiophene confirmed by NBO and AIM analyses. The interaction energies between [C8MIM]⁺[BF₄]^? and thiophene, dibenzothiophene, cyclohexane, toluene are 18.83, 20.93, 6.83, 12.99 kcal/mol, showing the preferential adsorption of dibenzothiophene and thiophene by ionic liquid, in agreement with the experimental results of dibenzothiophene and thiophene extraction by [C8MIM]⁺[BF₄]^?.     

(PPh4)[(ReO2S2)CuI] und (NEt4)2[(ReOS3)Cu3Cl4]: Fixierung der bisher nicht isolierten Ionen [ReO2S2]− und [ReOS3]− durch Ausnutzung der Stabilität der CuS2(Re)- und Cu3S3(Re)-Fragmente

(PPh₄)[(ReO₂S₂)CuI] and (NEt₄)₂[ReOS₃)Cu₃Cl₄]: Fixation of the up to now not Isolated Ions [ReO₂S₂]^? and [ReOS₃]^? Utilizing the Stability of the CuS₂(Re) and Cu₃S₃(Re) Fragments (PPh₄)[(ReO₂S₂)CuI] ( 1 ) and (NEt₄)₂[ReOS₃)Cu₃Cl₄] ( 2 ) containing the up to now not isolated oxothioperrhenate ions [ReO₂S₂]^? and [ReOS₃]^? as ligands, have been prepared by the reaction of (NEt₄)[ReS₄] with PPh₃ and CuI in acetone in the presence of (PPh₄)I (( 1 )) or with CuCl in CH₂Cl₂ in the presence of (NEt₄)Cl (( 2 )), respectively. 1 and 2 have been characterized by X-ray structure analysis, elemental analysis and spectroscopic studies (IR, UV/Vis). The electronic spectra show bands which can approximately be assigned to interesting low-energy charge-transfer-transitions of the type d(Cu) → d(Re). For crystal data see Inhaltsübersicht.     

Supramolecular inclusion of a pillared double-layered host by an anion-directed second-sphere coordination

In this paper, we have illustrated the utilisation of a second-sphere coordination approach to construct supramolecular inclusion solids with varieties of guest molecules. A flexible molecule N,N,N′,N′-tetra-p-methylbenzyl-ethylenediamine (L1) bearing doubly protonated H-bond donors was designed, capable of forming N–H…Cl hydrogen bonds with a crystallographically unique chloride anion, to construct an anion-directed ligand. The pillared double-layered host framework was constructed by an anion-directed ligand and primary coordination sphere [CoCl₄]^2 ?  through weak C–H…Cl hydrogen-bonding interactions. A variety of guest molecules, such as p-anisaldehyde, 1,4-dimethoxy-2,5-bis(methoxymethyl)benzene, can be included, leading to the formation of novel supramolecular inclusion solids: [L1]·4[H]⁺·[CoCl₄]^2 ? ·2Cl^? ·1.5[C₈H₈O₂]·0.25[CH₃OH] (1) and [L1]·4[H]⁺·[CoCl₄]^2 ? ·2Cl^? ·1.5[C₁₂H₂₀O₄]·0.5[CH₃OH] (2).

We have presented herein the utilisation of a second-sphere coordination approach to construct supramolecular inclusion solids with a variety of guest molecules. A novel type of a pillared double-layered host framework was constructed by a second-sphere coordination between the anion-directed ligand (L1 = N,N,N′,N′-tetra-p-methylbenzyl-ethylenediamine) and [CoCl₄]^2 ?  through weak C–H…Cl hydrogen-bonding interaction, and a variety of guest molecules, such as p-anisaldehyde, 1,4-dimethoxy-2,5-bis(methoxymethyl)benzene, can be included, leading to the formation of supramolecular inclusion solids: [L1]·4[H]⁺·[CoCl₄]^2 ? ·2Cl^? ·1.5[C₈H₈O₂]·0.25[CH₃OH] (1) and [L1]·4[H]⁺·[CoCl₄]^2 ? ·2Cl^? ·1.5[C₁₂H₂₀O₄]·0.5[CH₃OH] (2)

     

Isolation of a Three‐Coordinate Boron Cation with a Boron–Sulfur Double Bond

The reaction of the bulky bis(imidazolin‐2‐iminato) ligand precursor (1,2‐(L^MesNH)₂‐C₂H₄)[OTs]₂ ( 1 ²⁺ 2[OTs]^?; L^Mes=1,3‐dimesityl imidazolin‐2‐ylidene, OTs=p‐toluenesulfonate) with lithium borohydride yields the boronium dihydride cation (1,2‐(L^MesN)₂‐C₂H₄)BH₂[OTs] ( 2 ⁺ [OTs]^?)_. The boronium cation 2 ⁺ [OTs]^? reacts with elemental sulfur to give the thioxoborane salt (1,2‐(L^MesN)₂‐C₂H₄)BS[OTs] ( 3 ⁺ [OTs]^?). The hitherto unknown compounds 1 ²⁺ 2[OTs]^?, 2 ⁺ [OTs]^?, and 3 ⁺ [OTs]^? were fully characterized by spectroscopic methods and single‐crystal X‐ray diffraction. Moreover, DFT calculations were carried out to elucidate the bonding situation in 2 ⁺ and 3 ⁺. The theoretical, as well as crystallographic studies reveal that 3 ⁺ is the first example for a stable cationic complex of three‐coordinate boron that bears a B?S double bond.     

Thiochloroanionen von Molybdän(IV). Die Kristallstruktur von (NEt4)3[Mo3(μ3-S)(μ-S2)3Cl6]Cl · CH2Cl2 Kristallstruktur,EPR-Spektrum und magnetische Eigenschaften von (NEt4)2[Mo2(μ-S2)(μ-Cl)2Cl6]

Thiochloro Anions of Molybdenum (IV). Crystal Structure of (NEt₄)₃[Mo₃(μ₃-S)(μ-S₂)₃Cl₆]Cl μ CH₂Cl₂. Crystal Structure, Magnetic Properties, and EPR-Spectrum of (NEt₄)₂ [Mo₂(μ-S₂)(μ-Cl)₂Cl₆] From molybdenum pentachloride and tetraethylammonium hydrogensulfide in CH₂Cl₂ an insoluble product of composition (NEt₄)₂[Mo₂S₃Cl₉] was obtained along with a brown solution, from which (NEt₄)₂[Mo₂(S₂)Cl₈] was crystallized. The insoluble product and NEt₄Cl react in CH₂Cl₂ to yield, among others, (NEt₄)₃[Mo₃(S)(S₂)₃Cl₆]Cl · CH₂Cl₂. The latter crystallizes in the orthorhombic space group Pnma, a = 2495.8, b = 1501.2, c = 1295.6 pm, Z = 4. According to the crystal structure determination (3070 observed reflexions, R = 0.049) the [Mo₃(S)(S₂)₃Cl₆]^2? ion consists of an Mo₃ triangle with Mo? Mo bonds, each side of the triangle is bridged by disulfido groups and one sulfur atom is capped over the Mo₃ triangle; the single chloride ion is looseley associated to three S atoms. (NEt₄)₂[Mo₂(S₂)Cl₈] also crystallizes in the space group Pnma, a = 1425.6, b = 1129.9, c = 2004.7 pm, Z = 4; structure determination with 1703 observed reflexions, R = 0.061. In the [Mo₂(S₂)Cl₈]^2? ion the Mo atoms are bridged via one disulfido group and two chlorine atoms. There is a Mo? Mo bond, but according to the magnetic properties and the EPR spectrum each Mo atom still possesses one unpaired electron.     

Homoleptic Gold Acetonitrile Complexes with Medium to Very Weakly Coordinating Counterions: Effect on Aurophilicity?

A series of gold acetonitrile complexes [Au(NCMe)₂]⁺[WCA]^? with weakly coordinating counterions (WCAs) was synthesized by the reaction of elemental gold and nitrosyl salts [NO]⁺[WCA]^? in acetonitrile ([WCA]^? = [GaCl₄]^?, [B(CF₃)₄]^?, [Al(OR^F)₄]^?; R^F = C(CF₃)₃). In the crystal structures, the [Au(NCMe)₂]⁺ units appeared as monomers, dimers, or chains. A clear correlation between the aurophilicity and the coordinating ability of counterions was observed, with more strongly coordinating WCAs leading to stronger aurophilic contacts (distances, C?N stretching frequencies of [Au(NCMe)₂]⁺ units). An attempt to prepare [Au(L)₂]⁺ units, even with less weakly basic solvents like CH₂Cl₂, led to decomposition of the [Al(OR^F)₄]^? anion and formation of [NO(CH₂Cl₂)₂]⁺[F(Al(OR^F)₃)₂]^?. All nitrosyl reagents [NO]⁺[WCA]^? were generated according to an optimized procedure and were thoroughly characterized by Raman and NMR spectroscopy. Moreover, the to date unknown species [NO]⁺[B(CF₃)₃CN]^? was prepared. Its reaction with gold unexpectedly produced [Au(NCMe)₂]⁺[Au(NCB(CF₃)₃)₂]^?, in which the cyanoborate counterion acts as an anionic ligand itself. Interestingly, the auroborate anion [Au(NCB(CF₃)₃)₂]^? behaves as a weakly coordinating counterion, which becomes evident from the crystallographic data and the vibrational spectral characteristics of the [Au(NCMe)₂]⁺ cation in this complex. Ligand exchange in the only room temperature stable salt of this series, [Au(NCMe)₂]⁺[Al(OR^F)₄]^?, is facile and, for example, [Au(PPh₃)(NCMe)]⁺[Al(OR^F)₄]^? can be selectively generated. This reactivity opens the possibility to generate various [AuL¹L²]⁺[Al(OR^F)₄]^? salts through consecutive ligand‐exchange reactions that offer access to a huge variety of Au^I complexes for gold catalysis.     

The Sulfur Rich Fluorothiophosphate Dianions [S5P2F2]2− and [S3PF]2− : Cluster and Chelation Control of P-S Heterolysis

The sulfur rich difluoropentathiodiphosphate dianion [S₅P₂F₂]²⁻, from fluoride addition to P₄S₁₀, has a somewhat checkered history and proves to be the main product of the reaction in acetonitrile. Its optimized synthesis, and structural characterization, as either a tetraphenylphosphonium or a tetrapropylammonium salt, [NⁿPr₄]₂[S₅P₂F₂] allows for the first coordination chemistry for this dianion. Reactions of [S₅P₂F₂]²⁻ with d¹⁰ metal ions of zinc(II), and cadmium(II), and d⁹ copper(II) resulted in a surprising diverse array of binding modes and structural motifs. In addition to the simple bis-chelate coordination of [S₅P₂F₂]²⁻ with zinc, cleavage of the P−S bond resulted in complexes with the unusual [S₃PF]²⁻ fluorotrithiophosphate dianion. This was observed in two cluster complexes: a trinuclear cadmium complex with mixed [S₅P₂F₂]²⁻/[S₃PF]²⁻ ligands, [Cd₃(S₅P₂F₂)₃(S₃PF)₂]⁴⁻ as well as an octanuclear copper cluster, [Cu₈(S₃PF)₆]⁴⁻ which form rapidly at room temperature. These new metal/sulfur/ligand clusters are of relevance to understanding multimetal binding to metallothionines, and to potential capping strategies for the condensed nanoparticulate cadmium chalcogenide semiconductors CdS and CdSe.     

Solubility of Elemental Sulfur in Water at 298 K

Abstract

The solubility of elemental rhombic sulfur in water is 1.9(±0.6) × 10^?8 mole S₈·kg^?1. This value is in agreement with thermodynamic considerations on the solubility of sulfur and experimental data on sulfur hydrosols.     

Pentabromothio-diarsenat und -diantimonat: Darstellung,Schwingungsspektren und Kristallstrukturen von PPh4[As2SBr5] und PPh4[Sb2SBr5]

Pentabromothio-diarsenate and -diantimonate: Preparation, Vibrational Spectra, and Crystal Structures of PPh₄[As₂SBr₅] and PPh₄[Sb₂SBr₅] The title compounds were obtained in CH₂Br₂ from PPh₄Br, HBr and As₂S₃ or Sb₂S₃, respectively. Their i.r. and Raman spectra are reported. Their crystal structures were determined by X-ray diffraction. Crystal data: PPh₄[As₂SBr₅], monoclinic, space group P2₁/n, Z = 4, a = 1192.3, b = 1528.1, c = 1618.0 pm, β = 95.53°, isotypic with PPh₄[As₂SCl₅] (structure determination with 1539 observed reflexions, R = 0.052); PPh₄[Sb₂SBr₅], triclinic, space group P1 , Z = 2, a = 1044,8, b = 1207.1, c = 1307.8 pm, α = 104.77, β = 108.63, γ = 98.34° (2398 observed reflexions, R = 0.032). Both ions, [As₂SBr₅]^? and [Sb₂SBr₅]^?, have the same general structure: including the lone electron pairs, the As and Sb atoms have distorted trigonal-bipyrimidal coordination, two bipyramids sharing a common edge with sulfur and bromine as bridging atoms. The [As₂SBr₅]^? ions are associated to chains via As…Br contacts, the [Sb₂SBr₅]^? ions form pseudodimeric units by Sb…S and Sb…Br contacts. Whereas the crystal packing of the As compound is similar to that of other PPh₄⁺ compounds having a cation to anion ratio of 1:1, the Sb compound shows the packing principle known for 2:1 compounds.     

Stereochemistry of 2, 7-disubstituted and 1,2,7-trisubstituted 4-alkyldecahydro-4-quinolols

The configurations of the 2 and 4 centers in 1,2,7-trimethyl-, 2,7-dimethyl-, and 1,2-dimethyl-7-tert-butyl-4-alkyldecahydro-4-quinolols were assigned on the basis of a comparison of the^I[M-CH₃] +/^I _[M] ⁺ and I_[m] + peak intensity ratios (the [M-CH₃) + and [M-C₂H₅]⁺ ions are due to elimination of 2-CH₃ and 4-C₂H₅ groups, respectively) in the mass spectra of the stereoisomers.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 809–811, June, 1976.     

A6Nb4S22 (A = Rb and Cs), compounds with the tetrameric complex anion [Nb4S22]6−: Preparation via the molten flux method and crystal structure determination

The new ternary niobium polysulfides A₆Nb₄S₂₂ were prepared at a low temperature of 350°C via the molten flux method by reacting A₂S₃ (A = Rb, Cs) with niobium metal and additional sulfur. The crystal structure is characterized by [Nb₄S₂₂]^6? anions. Two Nb₂S₁₀ subunits are joined by a S₂^2?. Nb⁵⁺ is coordinated by S₂^2? and S^2? ligands according to [Nb₂(μ-η², η¹-S₂)(η²-S₂)₃(S)₂]₂(μ-η¹-S₂)^6?. Every Nb is in a sixfold coordination, and the polyhedra can be regarded as strongly distorted pentagonal pyramids. Within the unit cell the anions are stacked in “rods” parallel to the crystallographic b-axis. These stacks are arranged in “layers” and the A⁺ ions are located between the layers.     

Synthese und Struktur des μ-Sulfido-μ-disulfido-octabromodiwolframat(V)-Ions [W2S3Br8]2−

Synthesis and Structure of μ-Sulfido-μ-disulfido-octabromoditungstate(V), [W₂S₃Br₈]^?2 Tungsten hexabromide reacts with H₂S in dichloromethane yielding a brown product which, by addition of tetraphenylphosphonium bromide in CH₂Cl₂, is converted to brown, crystalline (PPh₄)₂[Br₄W(μ-S)(μ-S₂)WBr₄] · CH₂Cl₂ · CH₂S. Its IR spectrum is reported, its crystal structure was determined by X-ray diffraction (2330 reflexions, R = 0.097). Crystal data: orthorhombic, Pnma, a = 1 766.5, b = 2 412.7, c = 1 416.3 pm, Z = 4. In the diamagnetic [W₂S₃Br₈]^2? ions the two W atoms are linked via a sulfido and a disulfido bridge and by a W? W bond.     

Supramolecular Adduct of γ-Cyclodextrin and [{Re<Subscript>6</Subscript>Q<Subscript>8</Subscript>}(H<Subscript>2</Subscript>O)<Subscript>6</Subscript>]<Superscript>2+</Superscript> (Q=S,Se)

Slow evaporation of water solution of [{Re₆S₈}(H₂O)₆]²⁺ generated in situ from [{Re₆S₈}(OH)₆]^4– in presence of γ-cyclodextrin (CD) leads to crystallization of {[{Re₆S₈}(H₂O)₆] ? [γ-CD]}(NO₃)₂·12H₂O (1·12H₂O) supramolecular complex, which was characterized by single-crystal X-ray diffraction crystallography, IR-spectroscopy, thermogravimetric and elemental analyses. X-ray analysis confirms the formation of 1:1 {[{Re₆S₈}(H₂O)₆] ? [γ-CD]}²⁺ inclusion compound in the solid state. However, no adduct formation was detected between [{Re₆S₈}(H₂O)₆]²⁺ and γ-cyclodextrin in solution, according to ¹H NMR spectroscopy. In the case of in situ generated [{Re₆Se₈}(H₂O)₆]²⁺ the reaction solution with γ-cyclodextrin is unstable and during the crystallization only amorphous precipitate has been obtained.     

Phospha-alkynes - Useful Building Blocks in Organic Chemistry1

Abstract

The syntheses of phospholes (7, [3+2]-cycloaddition), bicyclophosphaalkenes (17, [4+2]-cycloaddition), and phosphabenzenes (15, [4+2]-cycloaddition followed by an extrusion process) starting from the phosphaalkynes (4) are described. The 2–Dewar phosphabenzene 18, obtained from the cyclobutadiene 21 and 4 (R =^tBu), is the starting material for the synthesis of the valency isomers 19, 20, 22, and 23.     

Synthese und Kristallstrukturen von (NEt4)2[TeS3], (NEt4)2[Te(S5)(S7)] und (NEt4)4[Te(S5)2][Te(S7)2]

Synthesis and Crystal Structures of (NEt₄)₂[TeS₃], (NEt₄)₂[Te(S₅)(S₇)], and (NEt₄)₄[Te(S₅)₂][Te(S₇)₂] (NEt₄)₂[TeS₃] was obtained by the reaction of NEt₄Cl, Na₂S₄ and tellurium in acetonitrile. It reacts with sulfur, yielding (NEt₄)₂[Te(S₅)(S₇)], which is transformed to (NEt₄)₄[Te(S₅)₂][Te(S₇)₂] by recrystallization from hot acetonitrile. According to the X-ray structure analysis, crystals of (NEt₄)₂[TeS₃] are monoclinic (space group P2₁/c) and form twins with the twinning plane (001); they contain pyramidal TeS₃^2– ions. (NEt₄)₂[Te(S₅)(S₇)] forms triclinic twins (space group P1) with the twinning plane (010). In the [Te(S₅)(S₇)]^2– ion an S₅ and an S₇ atom group are bonded in a chelate manner to the tellurium atom, which has square coordination. (NEt₄)₄[Te(S₅)₂][Te(S₇)₂] (monoclinic, space group P2₁/c) contains two kinds of anions, the known [Te(S₅)₂]^2– and the new [Te(S₇)₂]^2– ion which has two S₇ chelating groups.     

POLYCYCLES AND CAGES IN MOLECULAR ALUMO-POLYSILOXANES—(Ph2SiO)8[Al(O)OH]4 Used as a Supramolecular Target and “Auto-Condensation” Within the Molecule

In this preliminary review the reaction of [Ph₂SiO]₈[AlO(OH)]₄ toward 1,3-diaminopropane and hexamethyldisilazane is discussed in view of supramolecular chemistry and access to structural transformations of the original polycycle. Two distinct adducts may be isolated in the first case: [Ph₂SiO]₈[AlO(OH)]₄· 3H₂N-CH₂CH₂CH₂-NH₂ and [Ph₂SiO]₈[AlO(OH)]₄· 2H₂N-CH₂CH₂CH₂-NH₂. Whereas in the 1:3 adduct the four protic hydrogen atoms of the inner Al₄(OH)₄ ring are involved in O…H…N hydrogen bridges to two terminal diaminopropanes and a bridging diaminopropane thus forming an O…H…N(H)₂-CH₂CH₂CH₂N(H)₂ …H…O loop, in the 1:2 adduct two such O…H…N(H)₂-CH₂CH₂CH₂N(H)₂…H…O loops are present. When [Ph₂SiO]₈[AlO(OH)]₄ is allowed to react with hexamethyldisilazane, again two different products may be obtained depending on the solvent: [Ph₂SiO]₈[AlO₂]₂[AlOO-SiMe₃]₂[NH₄· THF]₂ or [Ph₂SiO]₈[AlOO_0.5]₄· 2 py. This last reaction may be viewed as an inner condensation within [Ph₂SiO]₈[AlO(OH)]₄ loosing two equivalents of water. Both products of the reaction with hexamethyldisilazane have an inner Al₂O₂ four-membered cycle in common, to which Al₂O₄Si₂ eight-membered cycles are partly fused.     

Mixed‐Valent Europium in the Cubic Thiosilicate Li3Eu6[SiS4]4

In an attempt to synthesize LiEu₃S₃[SiS₄] utilizing elemental europium and sulfur as well as SiS₂ and an excess of LiCl as flux and lithium source, dark red, platelet‐shaped single crystals of Li₃Eu₆[SiS₄]₄ were obtained. This new compound crystallizes in the cubic space group I4 3d (a = 1369.22(5) pm) with four formula units per unit cell. Both the Li⁺ and the Si⁴⁺ cations are surrounded by four sulfide anions. The [SiS₄]^4– tetrahedra show merely a slight trigonal distortion, while the [LiS₄]^7– units are best described as flattened bisphenoids. The europium cations exhibit an eightfold, rather irregular coordination environment by eight S^2– anions and have to be regarded mixed‐valent with a +2:+3 charge‐ratio of 5:1 in order to gain electroneutrality. The lack of an inversion center is caused by the [SiS₄]^4– tetrahedra being stacked exclusively top up along [111] in this acentric crystal structure.