The Crystal Structures of Two No–Metal Tricyanomelaminates: Diammonium Tricyanomelaminate Dihydrate [NH4]2[C6N9H] · 2 H2O and Dimelaminium Tricyanomelaminate Melamine Dihydrate [C3N6H7]2[C6N9H] · C3N6H6 · 2 H2O

Diammonium tricyanomelaminate dihydrate [NH₄]₂[C₆N₉H] · 2 H₂O ( 1 ) and dimelaminium tricyanomelaminate melamine dihydrate [C₃N₆H₇]₂[C₆N₉H] · C₃N₆H₆ · 2 H₂O ( 2 ) were obtained by metathesis reactions from Na₃[C₆N₉] in aqueous solution and characterized by single‐crystal X‐ray diffraction and ¹⁵N solid‐state NMR spectroscopy ( 1 ). Both salts contain mono‐protonated tricyanomelaminate (TCM) anions and crystallize as dihydrates. Considering charge balance requirements, the crystal structure of 1 (C2/c, a = 3181.8(6) pm, b = 360.01(7) pm, c = 2190.4(4) pm, β = 112.39(3)°, V = 2319.9(8) 10⁶ · pm³) can best be described by assuming a random distribution of an ammonium ion – crystal water pair over two energetically similar sites. Apart from two melaminium cations, 2 (P2₁/c, a = 674.7(5) pm, b = 1123.6(5) pm, c = 3400.2(5) pm, β = 95.398(5), V = 2566(2) 10⁶ · pm³) contains one neutral melamine per formula unit acting as an additional “solvent” molecule and yielding a donor‐acceptor type of π–stacking interaction.     

Domino Reactions with 2-Fluoro-3-trifluoromethylfurans and -thiophenes [1]

Summary.  The single fluorine atom of 2-fluoro-3-trifluoromethylfurans and -thiophenes can be readily replaced by various nucleophiles. Depending on the substituent pattern, certain products obtained upon nucleophilic substitution with benzyl alcohols are susceptible to [1,3]- and [1,5]-benzyl group migrations under very mild conditions. Therefore, these rearrangements can be integrated into domino reactions. Received March 9, 2001. Accepted April 2, 2001     

Monoammoniates of Aluminium Halides: The Crystal Structures of AlBr3 · NH3 and AlI3 · NH3

Single crystals of AlBr₃ · NH₃ and AlI₃ · NH₃ sufficient in size for X‐ray structure determinations were obtained by evaporation/ sublimation of the respective compound from its melt. The ammoniates were synthesized by the reaction of the pure halide with NH₃ at ‐78°C and following homogenization by slowly heating the reaction mixture up to the melting points of the ammoniates (124°C and 126°C, respectively). The X‐ray structure determinations for both monoammoniates were successfully carried out for the heavy atom positions (no hydrogen atoms): AlBr₃ · NH₃: Pbca, Z = 16, a = 11.529 (5) Å, b = 12.188 (2) Å, c = 19.701 (4) Å AlI₃ · NH₃: Pbca, Z = 8, a = 13.536 (5) Å, b = 8.759 (2) Å, c = 14.348 (4) Å The structures contain tetrahedral molecules Al(NH₃)X₃ with X = Br, I. They are not isotypic. The main difference is given for the coordination of NH₃ by X^‐ from neighbouring molecules. In Al(NH₃)Br₃ one of the two crystallographically independent NH₃ ligands has 6Br^‐ and the other 7Br^‐ as neighbours whereas in Al(NH)₃I₃ only 5I^‐ surround the one kind of NH₃.     

New coordination modes in potassium edta salts: K2[H2edta]·2H2O,K3[Hedta]·2H2O and K4[edta]·3.92H2O

Three potassium edta (edta is ethylenediaminetetraacetic acid, H₄Y) salts which have different degrees of ionization of the edta anion, namely dipotassium 2‐({2‐[bis(carboxylatomethyl)azaniumyl]ethyl}(carboxylatomethyl)azaniumyl)acetate dihydrate, 2K⁺·C₁₀H₁₄N₂O₈²⁻·2H₂O, (I), tripotassium 2,2′‐({2‐[bis(carboxylatomethyl)amino]ethyl}ammonio)diacetate dihydrate, 3K⁺·C₁₀H₁₃N₂O₈³⁻·2H₂O, (II), and tetrapotassium 2,2′,2′′,2′′′‐(ethane‐1,2‐diyldinitrilo)tetraacetate 3.92‐hydrate, 4K⁺·C₁₀H₁₂N₂O₈⁴⁻·3.92H₂O, (III), were obtained in crystalline form from water solutions after mixing edta with potassium hydroxide in different molar ratios. In (II), a new mode of coordination of the edta anion to the metal is observed. The HY³⁻ anion contains one deprotonated N atom coordinated to K⁺ and the second N atom is involved in intramolecular bifurcated N—H...O and N—H...N hydrogen bonds. The overall conformation of the HY³⁻ anions is very similar to that of the Y⁴⁻ anions in (III), although a slightly different spatial arrangement of the –CH₂COO⁻ groups in relation to (III) is observed, whereas the H₂Y²⁻ anions in (I) adopt a distinctly different geometry. The preferred synclinal conformation of the –NCH₂CH₂N– moiety was found for all edta anions. In all three crystals, the anions and water molecules are arranged in three‐dimensional networks linked via O—H...O and C—H...O [and N—H...O in (I) and (II)] hydrogen bonds. K...O interactions also contribute to the three‐dimensional polymeric architecture of the salts.     

Synthese und Kristallstruktur von [WNCl3 · NC–Ph]4 · 3 CH2Cl2

Synthesis and Crystal Structure of [WNCl₃ · NCPh]₄ · 3 CH₂Cl₂ The adduct of tungsten nitride trichloride with benzonitrile, [WNCl₃ · NCPh]₄, is formed by the reaction of N,N,N'-tris(trimethylsilyl)benzamidine and tungsten hexachloride in CCl₄ solution. It forms red crystal needles and was characterized by its IR spectrum and an X-ray crystal structure determination (1983 unique observed reflexions, R = 0.075). Crystal data: a = 1464.8, b = 1902.6, c = 2033.8 pm, β = 102.27°, space group C2/c, Z = 4. In the [WNCl₃ · NCPh]₄ molecule the tungsten atoms were located at the vertices of a square and are linked with one another via linear W?N? W nitrido bridges with alternating short and long bonds having average lengths of 166 and 211 pm. The N atoms of the benzonitrile ligands are in the positions trans to the W?N bonds at distances of 237 pm.     

Tetrahedral [Tt4]4– Zintl Anions Through Solution Chemistry: Syntheses and Crystal Structures of the Ammoniates Rb4Sn4·2NH3, Cs4Sn4·2NH3, and Rb4Pb4·2NH3

The crystalline isotypic solvates Rb₄Sn₄·2NH₃, Cs₄Sn₄·2NH₃, and Rb₄Pb₄·2NH₃ have been synthesized using the direct reduction of elemental tin or tetraphenyltin, respectively, with heavier alkali metals or the dissolution of the binary phase RbPb in liquid ammonia. These compounds contain the cluster ions [Sn₄]^4– or [Pb₄]^4– respectively. This is the first time that[Tt₄]^4– ions (Tt = tetrels) are detected as result of a solution reaction. The accommodation of the ammonia molecules, which build up ion‐dipole interactions to alkali metal cations, requires some modifications of the crystal structures compared to the binary phases RbSn, CsSn, and RbPb. The tetrahedral [Tt₄]^4– anions have a slightly lower coordination by Rb⁺ or Cs⁺ cations and, furthermore, the intercluster distances show a remarkable increase.     

Syntheses,Crystal Structures,and Properties of the Isotypic Pair [Cr(H2O)6]2[B12H12]3·15H2O and [In(H2O)6]2[B12H12]3·15H2O

Single crystals of [Cr(H₂O)₆]₂[B₁₂H₁₂]₃ · 15H₂O and [In(H₂O)₆]₂[B₁₂H₁₂]₃ · 15H₂O were obtained by reactions of aqueous solutions of the acid (H₃O)₂[B₁₂H₁₂] with chromium(III) hydroxide and indium metal shot, respectively. The title compounds crystallize isotypically in the trigonal system with space group R$\bar{3}$ c (a = 1157.62(3), c = 6730.48(9) pm for the chromium, a = 1171.71(3), c = 6740.04(9) pm for the indium compound, Z = 6). The arrangement of the quasi‐icosahedral [B₁₂H₁₂]^2– dianions can be considered as stacking of two times nine layers with the sequence …ABCCABBCA… and the metal trications arrange in a cubic closest packed …abc… stacking sequence. The metal trications are octahedrally coordinated by six water molecules of hydration, while another fifteen H₂O molecules fill up the structures as zeolitic crystal water or second‐sphere hydrating species. Between these free and the metal‐bonded water molecules, bridging hydrogen bonds are found. Furthermore, there is also evidence of hydrogen bonding between the anionic [B₁₂H₁₂]^2– clusters and the free zeolitic water molecules according to B–H^δ– ··· ^δ+H–O interactions. Vibrational spectroscopy studies prove the presence of these hydrogen bonds and also show slight distortions of the dodecahydro‐closo‐dodecaborate anions from their ideal icosahedral symmetry (I_h). Thermal decomposition studies for the example of [Cr(H₂O)₆]₂[B₁₂H₁₂]₃ · 15H₂O gave no hints for just a simple multi‐stepwise dehydration process.     

Die Kristallstrukturen von [Ph3PMe]Cl·CH2Cl2, [Ph4P]NO3·CH2Cl2 und [Ph4P]2[SiF6]·CH2Cl2

Crystal Structures of [Ph₃PMe]Cl·CH₂Cl₂, [Ph₄P]NO₃·CH₂Cl₂, and [Ph₄P]₂[SiF₆]·CH₂Cl₂ The crystal structures of the title compounds are determined by X‐ray diffraction. In all cases, the included dichloromethane molecules as well as the phosphonium cations are involved to form hydrogen bridges with the anions. [Ph₃PMe]Cl·CH₂Cl₂ ( 1 ): Space group , Z = 2, lattice dimensions at 100 K: a = 890.3(1), b = 988.0(1), c = 1162.5(1) pm, α = 106.57(1)°, β = 91.79(1)°, γ = 92.60(1)°, R₁ = 0.0253. [Ph₄P]NO₃·CH₂Cl₂ ( 2 ): Space group P2₁/n, Z = 4, lattice dimensions at 193 K: a = 1057.0(1), b = 1666.0(1), c = 1358.9(1) pm, β = 100.10(1)°, R₁ = 0.0359. [Ph₄P]₂[SiF₆]·CH₂Cl₂ ( 3 ): Space group , Z = 2, lattice dimensions at 193 K: a = 1063.9(1), b = 1233.1(1), c = 1782.5(2) pm, α = 76.88(1)°, β = 83.46(1)°, γ = 72.29(1)°, R₁ = 0.0332.     

Synthesis and Thermal Behaviour of Compounds in the System [Ph4P]Cl/BiCl3 and the Crystal Structures of [Ph4P]3[Bi2Cl9] · 2 CH2Cl2 and [Ph4P]2[Bi2Cl8] · 2 CH3COCH3

Six polynuclear chlorobismuthates are formed in the reaction between BiCl₃ and Ph₄PCl by variation of the molar ratio of the educts, the solvents and the crystallisation methods: [Ph₄P]₃[Bi₂Cl₉] · 2 CH₂Cl₂, [Ph₄P]₃[Bi₂Cl₉] · CH₃COCH₃, [Ph₄P]₂[Bi₂Cl₈] · 2 CH₃COCH₃, [Ph₄P]₄[Bi₄Cl₁₆] · 3 CH₃CN, [Ph₄P]₄[Bi₆Cl₂₂], and [Ph₄P]₄[Bi₈Cl₂₈]. We report the crystal structure of [Ph₄P]₃[Bi₂Cl₉] · 2 CH₂Cl₂ which crystallises with triclinic symmetry in the S. G. P1 No. 2, with the lattice parameters a = 13.080(3) Å, b = 14.369(3) Å, c = 21.397(4) Å, α = 96.83(1)°, β = 95.96(1)°, γ = 95.94(2)°, V = 3943.9(1) ų, Z = 2. The anion is formed from two face‐sharing BiCl₆‐octahedra. [Ph₄P]₂[Bi₂Cl₈] · 2 CH₃COCH₃ crystallises with monoclinic symmetry in the S. G. P2₁/n, No. 14, with the lattice parameters a = 14.045(5) Å, b = 12.921(4) Å, c = 17.098(3) Å, β = 111.10(2)°, V = 2894.8(2) ų, Z = 2. The anion is a bi‐octahedron of two square‐pyramids, joined by a common edge. The octahedral coordination is achieved with two acetone ligands. [Ph₄P]₄[Bi₄Cl₁₆] · 3 CH₃CN crystallises in the triclinic S. G., P1, No. 2, with the lattice parameters a = 14.245(9) Å, b = 17.318(6) Å, c = 24.475(8) Å, α = 104.66(3)°, β = 95.93(3)°, γ = 106.90(4)°, V = 5486(4) ų, Z = 2. Two Bi₂Cl₈ dimers in syn‐position form the cubic anion. Lattice parameters of [Ph₄P]₃[Bi₂Cl₉] · CH₃COCH₃ are also given. The solvated compounds are desolvated at approximately 100 °C. [Ph₄P]₃[Bi₂Cl₉] · 2 CH₂Cl₂ and [Ph₄P]₃[Bi₂Cl₉] · CH₃COCH₃ show the same sequence of phase transitions after desolvation. All compounds melt into a liquid in which some order is observed and transform on cooling into the glassy state.     

ChemInform Abstract: Sulfur Dioxide and Water: Structures and Energies of the Hydrated Species SO2·nH2O, [HSO3]‐·nH2O, [SO3H]‐·nH2O,and H2SO3·nH2O (n = 0—8)

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Crystal Structure and Thermal Behaviour of K2[CrF5·H2O]

K₂[CrF₅·H₂O] is monoclinic: a = 9.6835(3) Å, b = 7.7359(2) Å, c = 7.9564(3) Å, β = 95.94(1)°, Z = 4, space group C2/c (n^o 15). Its crystal structure was solved from its X‐ray powder pattern recorded on a powder diffractometer, using for the refinement the Rietveld method. It is built up from isolated octahedral [CrF₅·OH₂]^2? anions separated by potassium cations. The dehydration of K₂[CrF₅·H₂O] leads to anhydrous orthorhombic K₂CrF₅: a = 7.334(2) Å, b = 12.804(4) Å, c = 20.151(5) Å, Z = 16, space group Pbcn (n^o 60), isostructural with K₂FeF₅.     

Syntheses,Crystal Structures,and Reactivity of [enH]4[Sn2Se6]·en, [enH]4[Sn2Te6]·en and [enH]4[Sn2S6]: Known Anions within Novel Coordination Spheres obtained by Novel Synthesis Routes

The hexachalcogenodistannates K₆[Sn^III₂Se₆] or Li₄[Sn^IV₂Te₆]·8en were recently reported to simultaneously act as mild oxidants and chalcogenide sources in reactions with CoCl₂/LiCp* (Cp* = pentamethylcyclopentadienide) while the Sn—E (E = Se, Te) fragment is not kept in the products, e.g. [(Cp*Co)₃(μ₃‐Se)₂], [(Cp*Co)₃(μ₃‐Se)₂][Cl₂Co(μ₂‐Cl)₂Li(thf)₂] or [(Cp*Co)₄(μ₃‐Te)₄]. In search of related reagents with possibly different reaction behavior, we isolated and crystallographically characterized isotypic compounds [enH]₄[Sn^IV₂Se₆]�en ( 1 ), and [enH]₄[Sn^IV₂Te₆]·en ( 2 ) (en = 1, 2‐diaminoethane), that result from an uncommon disproportion/re‐arrangement reaction: distannate(III) K₆[Sn₂E₆] (E = Se, Te) was reacted with en·2HCl to yield 1 or 2 under disproportion of Sn^III to Sn^II and Sn^IV. Another pathway was necessary to synthesize the respective but solvent‐free thiostannate [enH]₄ [Sn^IV₂S₆] ( 3 ), since the phase “K₆[Sn₂S₆]” is unknown. This second method started out from SnCl₄·2THF and S(SiMe₃)₂ in en solution. However, using E(SiMe₃)₂ (E = Se, Te) instead of S(SiMe₃)₂, 1 and 2 are also obtained this way. 1—3 are the first chalcogenostannates that exhibit exclusively [enH]⁺ counterions. The compounds were characterized by means of X‐ray crystallography and NMR spectroscopy. They seem to be suitable for reactions towards group 8‐10 metal complexes. Preliminary experiments indicate that the binary anions 1 — 3 coordinated by 1‐aminoethylammonium ions react more slowly compared to the anionic phases tested until now.     

Supramolecular Assembling of Complex Tellurium Salts: Synthesis and Crystal Structures of {Cs[PhTeCl4]·CH3OH} and Cs[PhTeBr4]

The direct reaction between PhTeCl₃ and CsCl in methanol affords {Cs[PhTeCl₄]·CH₃OH}. Cs[PhTeBr₄] was prepared by refluxing [2‐Br‐C₅NH₅][PhTeBr₄] and CsCl in ethanol in the presence of an excess of HBr. In {Cs[PhTeCl₄]·CH₃OH} the [PhTeCl₄]^— units form dimers by secondary Te···Cl bonds with methanol molecules bridging adjacent Cs⁺ cations. In both compounds, the alkali metal cation interacts secondarily with the chlorine and bromine Te‐ligands, achieving singular coordination polyhedrons and holding the lattices in supramolecular tridimensional assemblies. The new complexes, {Cs[PhTeCl₄]·CH₃OH} and Cs[PhTeBr₄], crystallize in the space groups P2₁/c and P2₁/n, respectively. Only one such structure has been reported before.