Neue Synthesen und Kristallstrukturen von Bis(fluorphenyl)quecksilber,Hg(Rf)2 (Rf = C6F5, 2, 3, 4, 6‐F4C6H, 2, 3, 5, 6‐F4C6H, 2, 4, 6‐F3C6H2, 2, 6‐F2C6H3)

New Syntheses and Crystal Structures of Bis(fluorophenyl) Mercury, Hg(R_f)₂ (R_f = C₆F₅, 2, 3, 4, 6‐F₄C₆H, 2, 3, 5, 6‐F₄C₆H, 2, 4, 6‐F₃C₆H₂, 2, 6‐F₂C₆H₃) Bis(fluorophenyl) mercury compounds, Hg(R_f)₂ (R_f = C₆F₅, C₆HF₄, C₆H₂F₃, C₆H₃F₂), are prepared in good yields by the reactions of HgF₂ with Me₃SiR_f. The crystal structures of Hg(2, 3, 4, 6‐F₄C₆H)₂ (monoclinic, P2₁/n), Hg(2, 3, 5, 6‐F₄C₆H)₂ (monoclinic, C2/m), Hg(2, 4, 6‐F₃C₆H₂)₂ (monoclinic, P2₁/c) and Hg(2, 6‐F₂C₆H₃)₂ (triclinic, P1) are described.     

Synthesis and Characterization of [Br3][MF6] (M=Sb,Ir), as well as Quantum Chemical Study of [Br3]+ Structure,Chemical Bonding,and Relativistic Effects Compared with [XBr2]+ (X=Br,I, At,Ts) and [TsZ2]+ (Z=F,Cl, Br,I, At,Ts)

[Br₃][SbF₆] and [Br₃][IrF₆] were synthesized by interaction of BrF₃ with Sb₂O₃ or iridium metal, respectively. The former compound crystallizes in the orthorhombic space group Pbcn (No. 60) with a=11.9269(7), b=11.5370(7), c=12.0640(6) Å, V=1660.01(16) ų, Z=8 at 100 K. The latter compound crystallizes in the triclinic space group P (No. 2) with a=5.4686(5), b=7.6861(8), c=9.9830(9) Å, α=85.320(8), β=82.060(7), γ=78.466(7)°, V=406.56(7) ų, Z=2 at 100 K. Both compounds contain the cation [Br₃]⁺, which has a bent structure and is coordinated by octahedron-like anions [MF₆]⁻ (M=Sb, Ir). Experimentally obtained cell parameters, bond lengths, and angles are confirmed by solid-state DFT calculations, which differ from the experimental values by less than 2 %. Relativistic effects on the structure of the tribromonium(1+) cation are studied computationally and found to be small. For the heaviest analogues containing At and Ts, however, pronounced relativistic effects are found, which lead to a linear structure of the polyhalogen cation.     

Preparation and Structure of Rhenium Fluoride Trioxide ReO3F,and the Polymorphism of Rhenium Trifluoride Dioxide,ReO2F3

The methods of preparation of ReO₃F are revised. ReO₃F is an amorphous yellow solid that crystallizes into colorless needles after prolonged heating. Its structure is that of a fluorine and oxygen bridged chain with hexa coordinated rhenium atoms (a = 670.9(2), b = 596.6(2), c = 1030.6(4) pm, β = 90.057(7)°, space group P2/c. In presence of donor solvents ReO₃F·2L (L = (C₂H₅)₂O, (CH₃)₂O, THF) are formed. ReO₂F₃, if crystallized from HF, exists in two crystalline forms, both are fluorine bridged chain polymers. (ReO₂F₃‐I: a = 1539.7(3), b = 999.6(3), c = 924.4(2) pm, β = 95.25(1)°, space group P2₁/c; ReO₂F₃‐II: a = 544.9(1), b = 494.2(1), c = 1253.7(2) pm, β = 98.543(7)°, space group P2₁/c. ReO₂F₃ crystallizes from CFCl₃ or SO₂FCl as fluorine bridged cyclic trimer (a = 881.4(4), c = 822.1(6) pm, γ = 120°, space group P6₃/m, or fluorine bridged cyclic tetramer (a = 1107.8(2), b = 999.4(2), c = 1347.9(3) pm, space group Cmca).     

Reactions of Hexanuclear Niobium and Tantalum Halide Clusters with Mercury(II) Halides. I. Synthesis and structures of the semiconducting compounds [M6Br12(H2O)6][HgBr4] · 12H2O,MNb,Ta

A method for the preparation of new solvated clusters of the composition [M₆Br₁₂(H₂O)₆][HgBr₂X₂] · 12H₂O (M?Nb, Ta; X?Cl, Br, I) is given. The cubic crystals of [Nb₆Br₁₂(H₂O)₆][HgBr₄] · 12H₂O 1 and [Ta₆Br₁₂(H₂O)₆][HgBr₄] · 12H₂O 2 were characterized by the X-ray structure analysis: 1 : cubic, space group Fd3 m, a = 21.0072(6) Å, Z = 8, R = 0.051 (R_w = 0.066); 2 : cubic, space group Fd3 m, a = 20.9698(1) Å, Z = 8, R = 0.038 (R_w = 0.050). 1 and 2 contain octahedral cluster cation [M₆Br₁₂(H₂O)₆]²⁺ and tetrahedrally arranged [HgBr₄]^2? anion. The M? M bond distances are 2.949(1) Å for 1 and 2.9000(8) Å for 2 . The Hg? Br bond distances in [HgBr₄]^2? anion are 2.614(2) Å in 1 and 2.622(2) Å in 2 . The crystal packing patterns of the isostructural clusters 1 and 2 involve the three-dimensional hydrogen bond network; the crystalline water molecules act as donors of hydrogen to the bromine atoms of the cluster and [HgBr₄]^2? units, whereas the coordinated water molecules form hydrogen bonds to the crystalline water molecules. [Nb₆Br₁₂(H₂O)₆][HgBr₄] · 12H₂O is diamagnetic and semiconducting with the activation energy, E_a = 0.20 eV.     

Syntheses and Crystal Structures of the Cluster Compounds A2[(W6Br)Br] with A = K,Rb, Cs

K₂W₆Br₁₄ ( I ), Rb₂W₆Br₁₄ ( II ), and Cs₂W₆Br₁₄ ( III ) were formed by reactions of W₆Br₁₂ with the corresponding alkali metal bromides in evacuated silica tubes with a temperature gradient of 925 K/915 K. ( I ) crystallizes in the cubic space group Pn3 (no. 201), a = 13.808 Å, Z = 4, cP88. ( II ) crystallizes in the monoclinic space group C2/c (no. 15), a = 20.301 Å, b = 15.396 Å, c = 9.720 Å, β = 115.69°, Z = 4, mC88. ( III ) crystallizes in the trigonal space group P31c (no. 163), a = 10.180 Å, c = 15.125 Å, Z = 2, hP44. The crystal structures are composed of the isolated [(W₆Br)Br]^2– cluster anions and the alkali metal cations (d(W–W) = 2.635(2) Å, d(W–Brⁱ) = 2.624(4) Å, d(W–Br^a) = 2.595(4) Å). The shape of the anions is influenced by the crystal field symmetry, but the mean bond lengths are not changed by the cation size. The packing of the cluster anions corresponds to ccp pattern in ( I ) and hcp pattern in ( II ) and ( III ), respectively. The alkali metal cations in the octahedral holes are coordinated only by the Br^a ligands while those in the tetrahedral and trigonal-bipyramidal cavities are surrounded by Br^a and Brⁱ ligands. The details will be discussed and compared with other structures.     

High‐temperature monoclinic α‐SrHfF6, and isostructural α‐SrZrF6: associating Hf2F12 bipolyhedra and SrF8 snub disphenoids

The structure of the high‐temperature monoclinic variety α‐SrHfF₆ (strontium hafnium hexafluoride) [and of isostructural α‐SrZrF₆ (strontium zirconium hexafluoride)] associates Hf₂F₁₂ bipolyhedra and SrF₈ snub disphenoids, forming zigzag twisted [SrF₆]_n layers. The distribution of the Hf and Sr polyhedra forms a three‐dimensional framework which can be related to the family of anion‐excess ReO₃‐related superstructures. α‐SrHfF₆ corresponds to a new ABX₆ type and is compared to the other main families already described. A partial amorphization of this structure is observed in samples quenched from the melt.     

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.     

Syntheses and Properties of Tetrakis(pentafluorophenyl)tellurium,Te(C6F5)4, and Related Compounds — Single Crystal Structures of Tris(pentafluorophenyl)tellurium Bromide,Te(C6F5)3Br,Tris(pentafluorophenyl)tellurium Trifluoromethanesulfonate, [Te(C6F5)3][OSO2CF3], and Bis(pentafluorophenyl)tellurium Oxide,Te(C6F5)2O

Te(C₆F₅)₄ was prepared from the reactions of TeCl₄ or Te(C₆F₅)₂Cl₂ with Grignard reagents or AgC₆F₅ in moderate to good yields. Substitution reactions with Me₃SiX (X = Cl, Br, OSO₂CF₃), with equimolar amounts of Br₂, with AgNO₃ and with H[BF₄] or BF₃·OEt₂ yielded the Te(C₆F₅)₃X derivatives (X = Cl, Br, OSO₂CF₃, NO₃, BF₄). Oxidation reactions of Cd, Hg, and Pd⁰ complexes led to Te(C₆F₅)₂ and the corresponding bis(pentafluorophenyl) derivatives M(C₆F₅)₂ (M = Cd, Hg, Pd) and with InBr to In(C₆F₅)₂Br. From very slow hydrolysis of Te(C₆F₅)₄ the oxide Te(C₆F₅)₂O was prepared. The thermal decomposition, the NMR and mass spectra of the partially new compounds are discussed. The crystal structures of Te(C₆F₅)₃Br (monoclinic, P2₁/a, Z = 4), [Te(C₆F₅)₃][OSO₂CF₃] (monoclinic, P2₁/n, Z = 16) and [Te(C₆F₅)₂O]₂ (triclinic, P1¯, Z = 2) were determined.     

Syntheses and Crystal Structures of Hydrated Ternary Cerium Sulfates: Mixed‐valence K5Ce2(SO4)6·H2O and K2Ce(SO4)3·H2O

A new chemical and structural interpretation of K₅Ce₂(SO₄)₆·H₂O ( I ) and a redetermination of the structure of K₂Ce(SO₄)₃·H₂O ( II ) is presented. The mixed‐valent compound I crystallizes in the space group C2/c with a = 17.7321(3), b = 7.0599(1), c = 19.4628(4) Å, β = 112.373(1)° and Z = 4. Compound I has been discussed earlier with space group Cc. In the structure of I , there are pairs of edge sharing cerium polyhedra connected by sulfate oxygen atoms in the μ₃ bonding mode. These cerium dimers are linked through edge and corner sharing sulfate bridges, forming layers. The layers are joined by potassium ions which together with the water molecules are placed between the layers. No irregularity in the distribution of the Ce^III and Ce^IV to cause the lost of a crystallographic center of symmetry was detected. We suggest that the charge exerted by the extra f¹ electron for every cerium dimer is delocalized over the Ce1–O₂–Ce2 moiety in a non‐bonding mode. As a result, the oxidations state of each cerium ion is a mean value between III and IV at each atomic position. Compound II crystallizes in the space group C2 with a = 20.6149(2), b = 7.0742(1), c = 17.8570(1) Å, β = 122.720(1)° and Z = 8. The hydrogen atoms have been located and the absolute structure has been established. Neither hydrogen atom positions nor anisotropic displacement parameters were given in the previous reports. In compound II , the cerium polyhedra are connected by edge and corner sharing sulfate groups forming a three‐dimensional network. This network contains Z‐shaped channels hosting the charge compensating potassium ions.     

Heterotrimetallic Mixed‐Valent Molecular Precursors Containing Periodic Table Neighbors: Assignment of Metal Positions and Oxidation States

A known trinuclear structure was used to design the heterobimetallic mixed‐valent, mixed‐ligand molecule [Co^II(hfac)₃?Na?Co^III(acac)₃] ( 1 ). This was used as a template structure to develop heterotrimetallic molecules [Co^II(hfac)₃?Na?Fe^III(acac)₃] ( 2 ) and [Ni^II(hfac)₃?Na?Co^III(acac)₃] ( 3 ) via isovalent site‐specific substitution at either of the cobalt positions. Diffraction methods, synchrotron resonant diffraction, and multiple‐wavelength anomalous diffraction were applied beyond simple structural investigation to provide an unambiguous assignment of the positions and oxidation states for the periodic table neighbors in the heterometallic assemblies. Molecules of 2 and 3 are true heterotrimetallic rather than a statistical mixture of two heterobimetallic counterparts. Trinuclear platform 1 exhibits flexibility in accommodating a variety of di‐ and trivalent metals, which can be further utilized in the design of molecular precursors for the NaMM′O₄ functional oxide materials.     

Synthesis and Crystal Structure of the Fluoride‐Rich Rubidium Scandium Fluoride Oxosilicate Rb3Sc2F5Si4O10

The new quinary fluoride‐rich rubidium scandium oxosilicate Rb₃Sc₂F₅Si₄O₁₀ was obtained from mixtures of RbF, ScF₃, Sc₂O₃ and SiO₂ in sealed platinum ampoules after seventeen days at 700 °C. The colourless compound crystallises orthorhombically in space group Pnma with a = 962.13(5), b = 825.28(4), c = 1838.76(9) pm and Z = 4. For the oxosilicate partial structure, [SiO₄]^4– tetrahedra are connected in (001) by vertex‐sharing to form corrugated unbranched vierer single layers ${2}\atop{{\infty}}$ {[Si₄O₁₀]^4–} (d(Si–O) = 158–165 pm, ∠(O–Si–O) = 103–114°, ∠(Si–O–Si) = 125–145°) containing six‐membered rings. Similar oxosilicate layers with 6³‐net topology are well‐known for the mineral group of micas or in sanbornite Ba₂Si₄O₁₀. Regarding other systems, identical tetrahedral layers can be found in the synthetic borophosphate Mg(H₂O)₂[B₂P₂O₈(OH)₂] · H₂O. The Sc³⁺ cations are coordinated octahedrally by four F^– and two O^2– anions. These cis‐[ScF₄O₂]^5– octahedra (d(Sc–F) = 200–208 pm, d(Sc–O) = 202–205 pm) share one equatorial and two apical F^– anions with others to build up slightly corrugated ${1}\atop{{\infty}}$ {[Sc₂F${t}\atop{2/1}$ F${v}\atop{6/2}$ O${t}\atop{4/1}$ ]^7–} double chains along [010]. These are linked with the oxosilicate layers via two oxygen vertices to construct a three‐dimensional framework with cavities apt to host the three crystallographically independent Rb⁺ cations with coordination numbers of eleven, twelve and thirteen.     

Electronic structure,novel synthesis,and O—H...O and C—H...O interactions in two 6‐oxopiperidine‐2‐carboxylic acid derivatives

Molecules of (S)‐6‐oxo‐1‐(thiophen‐2‐ylmethyl)piperidine‐2‐carboxylic acid, C₁₁H₁₃NO₃S, crystallize as single enantiomers in the space group P2₁ and the thiophene ring is disordered over two positions, while (S)‐6‐oxo‐1‐(thiophen‐3‐ylmethyl)piperidine‐2‐carboxylic acid, C₁₁H₁₃NO₃S, crystallizes as a single enantiomer in the space group P2₁2₁2₁. Their absolute configurations were confirmed by anomalous dispersion effects in diffraction measurements on the crystals. The molecules of each compound are linked by a combination of strong O—H...O hydrogen bonds and weak C—H...O interactions, resulting in two‐ and three‐dimensional networks, respectively, in the crystal structures.     

Tuning Mixed‐Valent Eu2+/Eu3+ in Strontium Formate Frameworks for Multichannel Photoluminescence

Cooperative performance of mixed‐valent Eu²⁺/Eu³⁺ in single‐compound phosphors offers significant advantages in color rendering and luminescence efficiency, but their synthesis is challenging because of Eu²⁺ oxidation. Using the tunable nature of the metal‐ion nodes in metal–organic frameworks (MOFs), we present an in situ reduction and crystallization route for preparing MOFs and doping Eu²⁺/Eu³⁺ with a controlled ratio. These materials exhibit rich photoluminescence, including intrinsic‐ and sensitized‐emissions of Eu²⁺ and Eu³⁺, and long‐lived luminescence from charge transfer. Color rendering can be easily achieved by fine‐tuning the valence states of Eu. A linear relation between temperature and the intensity ratio of Eu²⁺/Eu³⁺ emissions provides outstanding properties for applications as self‐calibrated luminescent thermometers with a wide working temperature range. Further incorporation of Tb³⁺ into the MOFs results in white light, utilizing all Eu²⁺,Tb³⁺, and Eu³⁺ emissions in a single crystalline lattice.     

X‐Ray Diffraction and Mössbauer Spectroscopy Studies of Pressure‐Induced Phase Transitions in a Mixed‐Valence Trinuclear Iron Complex

The mixed‐valence complex Fe₃O(cyanoacetate)₆(H₂O)₃ ( 1 ) has been studied by single‐crystal X‐ray diffraction analysis at pressures up to 5.3(1) GPa and by (synchrotron) Mössbauer spectroscopy at pressures up to 8(1) GPa. Crystal structure refinements were possible up to 4.0(1) GPa. In this pressure range, 1 undergoes two pressure‐induced phase transitions. The first phase transition at around 3 GPa is isosymmetric and involves a 60° rotation of 50 % of the cyanoacetate ligands. The second phase transition at around 4 GPa reduces the symmetry from rhombohedral to triclinic. Mössbauer spectra show that the complex becomes partially valence‐trapped after the second phase transition. This sluggish pressure‐induced valence‐trapping is in contrast to the very abrupt valence‐trapping observed when compound 1 is cooled from 130 to 120 K at ambient pressure.     

High-Pressure Synthesis of Sc5P12N23O3 and Ti5P12N24O2 by Activation of the Binary Nitrides ScN and TiN with NH4F

Multinary transition metal nitrides and oxonitrides are a versatile and intriguing class of compounds. However, they have been investigated far less than pure oxides. The compounds Sc₅P₁₂N₂₃O₃ and Ti₅P₁₂N₂₄O₂ have now been synthesized from the binary nitrides ScN and TiN, respectively, by following a high-pressure high-temperature approach at 8 GPa and 1400 °C. NH₄F acts as a mineralizing agent that supports product formation and crystallization. The starting materials ScN and TiN are seemingly an uncommon choice because of their chemical inertness but, nevertheless, react under these conditions. Sc₅P₁₂N₂₃O₃ and Ti₅P₁₂N₂₄O₂ crystallize isotypically with Ti₅B₁₂O₂₆, consisting of solely vertex-sharing P(O/N)₄ tetrahedra forming two independent interpenetrating diamond-like nets that host TM(O/N)₆ (TM=Sc, Ti) octahedra. Ti₅P₁₂N₂₄O₂ is a mixed-valence compound and shows ordering of Ti³⁺ and Ti⁴⁺ ions.