Röntgenographische und schwingungsspektroskopische Untersuchung der Sulvanitmischkristalle Cu3Nb(SxSe1−x)4, Cu3Nb(SexTe1−x)4, und Cu3Ta(SxSe1−x)4 und Cu3Ta(SexTe1−x)4

X-Ray and Vibrational Studies of Sulvanite Mixed Cystals Cu₃Nb(S_xSe_1?x)₄, Cu₃Nb(Se_xTe_1?x)₄, Cu₃Ta(S_xSe_1?x)₄ and Cu₃Ta(Se_xTe_1?x)₄ Solid solutions Cu₃Nb(S_xSe_1?x)₄, Cu₃Nb(Se_xTe_1?x)₄, Cu₃Ta(S_xSe_1?x)₄ and Cu₃Ta(Se_xTe_1?x)₄ with sulvanite structure have been prepared in the range 0 ≤ x ≤ 1. The lattice constants in all systems obey the Vegard rule. Infrared and Raman spectra have been measured. The spectra of the compounds with mixed anion sublattices show additional peaks, compared to those of the end members, because besides the polyhedra MX₄ and MY₄ also groups MX₃Y, MX₂Y₂, and MXY₃ are present, and all groups are able to oscillate independently. By comparison of the peak intensities and the statistical frequency of the groups according to the composition, the additional valence vibrations could be attributed to the groups.     

Crystal and electronic structures of La2LiGe6−x (x = 0.21) and La2LiGe4Si2

The synthesis and characterization of a new ternary dilanthanum lithium hexagermanide, La₂LiGe_6−x (x = 0.21), belonging to the Pr₂LiGe₆ structure type, and a quaternary dilanthanum lithium tetragermanium disilicide, La₂LiGe₄Si₂, which crystallizes as an ordered variant of this type, are reported. In both structures, Li is on a site of mmm symmetry. All other atoms are on sites of m2m symmetry. These structures are new representatives of a homologous linear structure series based on structural fragments of the AlB₂, CaF₂ and ZrSi₂ structure types. The observed 17‐vertex polyhedra are typical for La atoms and the environment of the Li atom is cubic. Two Ge atoms are enclosed in a tetragonal prism with one added atom (nine‐vertex polyhedron). The trigonal prismatic coordination is typical for Ge or Si atoms. The metallic nature of the bonding is indicated by the interatomic distances and electronic structure calculations.     

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)^?.     

Thermolysis of the phenyltin chlorides,PhxSnCl4–x, (x=1−3): Products and pathways

The thermal degradation of triphenyltin chloride, diphenyltin dichloride and phenyltin trichloride has been studied by pyrolysis at 375°C in sealed tubes for various time periods. In all cases, biphenyl and tin(II) chloride are produced. For both phenyltin trichloride and diphenyltin dichloride, ter- and poly-phenyls are also obtained. In some cases tin(IV) chloride or elemental tin are obtained. Pathways that account for all observed products are presented.     

K and Ba distribution in the structures of the clathrate compounds KxBa16−x(Ga,Sn)136 (x = 0.8, 4.4, and 12.9) and KxBa8−x(Ga,Sn)46 (x = 0.3)

Studies of the K–Ba–Ga–Sn system produced the clathrate compounds K_0.8(2)Ba_15.2(2)Ga_31.0(5)Sn_105.0(5) [a = 17.0178 (4) Å], K_4.3(3)Ba_11.7(3)Ga_27.4(4)Sn_108.6(4) [a = 17.0709 (6) Å] and K_12.9(2)Ba_3.1(2)Ga_19.5(4)Sn_116.5(4) [a = 17.1946 (8) Å], with the type‐II structure (cubic, space group Fdm), and K_7.7(1)Ba_0.3(1)Ga_8.3(4)Sn_37.7(4) [a = 11.9447 (4) Å], with the type‐I structure (cubic, space group Pmn). For the type‐II structures, only the smaller (Ga,Sn)₂₄ pentagonal dodecahedral cages are filled, while the (Ga,Sn)₂₈ hexakaidecahedral cages remain empty. The unit‐cell volume is directly correlated with the K:Ba ratio, since an increasing amount of monovalent K occupying the cages causes a decreasing substitution of the smaller Ga in the framework. All three formulae have an electron count that is in good agreement with the Zintl–Klemm rules. For the type‐I compound, all framework sites are occupied by a mixture of Ga and Sn atoms, with Ga showing a preference for Wyckoff site 6c. The (Ga,Sn)₂₀ pentagonal dodecahedral cages are occupied by statistically disordered K and Ba atoms, while the (Ga,Sn)₂₄ tetrakaidecahedral cages encapsulate only K atoms. Large anisotropic displacement parameters for K in the latter cages suggest an off‐centering of the guest atoms.     

Darstellung von μ-Schwefeldisulfoniumsalzen [(CH3)2S?Sx?S(CH3)2]2+2A− (x = 1–3, A− = AsF6−, SbF6−, SbCl6−). Über die Analogie im Reaktionsverhalten zwischen Sulfanen und Sulfoniumsalzen

Preparation of μ-Sulfurdisulfonium Salts [(CH₃)₂S? S_x? S(CH₃)₂]²⁺2A^? (x = 1–3, A^? = AsF₆^?, SbF₆^?, SbCl₆^?). On the Analogy of the Reactivity of Sulfanes and Sulfonium Salts The preparation of the μ-sulfurdisulfonium salts [(CH₃)₂S? S_x? S(CH₃)₂]²⁺(A^?)₂ with x = 1–3 and A^? = AsF₆^?, SbF₆^?, SbCl₆^? is reported. The salts are formed by reaction of (CH₃)₂SH⁺A^? and (CH₃)₂SSH⁺A^? with SCl₂ and S₂Cl₂, resp. They are characterized by vibrational spectroscopic measurements. [(CH₃)₂S? S₂? S(CH₃)₂]²⁺(SbF₆^?)₂ crystallizes in the space group C2/c with a = 1 884.5(7) pm, b = 1 302.8(5) pm, c = 1 477.2(5) pm, β = 98.62(3)° und Z = 8.     

Theoretical investigation on the photophysical properties of N‐heterocyclic carbene iridium (III) complexes (fpmb)xIr(bptz)3‐x (x = 1−2)

In the search for efficiently phosphorescent materials, this article presents a rational design and theoretical comparative study of some photophysical properties in the (fpmb)_xIr(bptz)_3‐x (x = 1–2), which involve the usage of two 2‐pyridyl triazolate ( bptz ) chromophores and a strong‐field ligand fpmb ( fpmb = 1‐(4‐difluorobenzyl)‐3‐methylbenzimidazolium). The first principle theoretical analysis under the framework of the time‐dependent density functional theory approach is implemented in this article to investigate the electronic structures, absorption and phosphorescence spectra. It is intriguing to note that 1 and 2 exhibit theirs blue phosphorescent emissions with maxima at 504 and 516 nm, respectively. Furthermore, to obtain the mechanism of low phosphorescence yield in 1 and estimate the radiative rate constant k_r for 2 , we approximately measure the radiative rate constant k_r, the spin‐orbital coupling (SOC) value, ΔE (S ? T), and the square of the SOC matrix element (<Ψ_S1.H_SO.Ψ_T1>²) for 1 and 2 . Finally, we tentatively come to conclusion that the switch of the cyclometalated ligand from the main to ancillary chelate seems to lower the splitting ΔE (S ? T) in the current system. © 2012 Wiley Periodicals, Inc. J Comput Chem, 2012     

An A‐Site Mixed‐Ammonium Solid Solution Perovskite Series of [(NH2NH3)x(CH3NH3)1−x][Mn(HCOO)3] (x=1.00–0.67)

The A‐site mixed‐ammonium solid solutions of metal–organic perovskites [(NH₂NH₃)_x(CH₃NH₃)_1?x][Mn(HCOO)₃] (x=1.00–0.67) exhibit para‐ to ferroelectric diffuse phase transitions with lowered transition temperatures from x=1.00 to 0.67. These properties are due to the decreased framework distortion and polarization in their low temperature ferroelectric phases caused by the increased CH₃NH₃⁺ concentration.     

Zur Kristallstruktur von CaLaAl3O7 und CaLaGa3−xAlxO7 (x = 0,66)

On the Crystal Structure of CaLaAl₃O₇ and CaLaGa_3?xAl_xO₇ (x = 0.66) Single crystals of (I): CaLaAl₃O₇ and (II): CaLaGa_2.34Al_0.66O₇ were grown from molten oxide mixtures and investigated by single crystal X-ray technique. Both compounds crystallize with tetragonal symmetry, space group D? P4 2₁m, (I): a = 7.8075; c = 5.1564 Å, (II): a = 7.9130, c = 5.2360 Å, Z = 2 and are isostructural with the Melilites. The crystal structure is discussed.     

Die Reaktionen von M[BF4] (M = Li,K) und (C2H5)2O·BF3 mit (CH3)3SiCN. Bildung von M[BFx>(CN)4—x] (M = Li,K; x = 1, 2) und (CH3)3SiNCBFx(CN)3—x, (x = 0, 1)

The Reactions of M[BF₄] (M = Li, K) and (C₂H₅)₂O·BF₃ with (CH₃)₃SiCN. Formation of M[BF_x(CN)_4—x] (M = Li, K; x = 1, 2) and (CH₃)₃SiNCBF_x(CN)_3—x, (x = 0, 1) The reaction of M[BF₄] (M = Li, K) with (CH₃)₃SiCN leads selectively, depending on the reaction time and temperature, to the mixed cyanofluoroborates M[BF_x(CN)_4—x] (x = 1, 2; M = Li, K). By using (C₂H₅)₂O·BF₃ the synthesis yields the compounds (CH₃)₃SiNCBF_x(CN)_3—x x = 0, 1. The products are characterized by vibrational and NMR‐spectroscopy, as well as by X‐ray diffraction of single‐crystals: Li[BF₂(CN)₂]·2Me₃SiCN Cmc2₁, a = 24.0851(5), b = 12.8829(3), c = 18.9139(5) Å V = 5868.7(2) ų, Z = 12, R₁ = 4.7%; K[BF₂(CN)₂] P4₁2₁2, a = 13.1596(3), c = 38.4183(8) Å, V = 6653.1(3) ų, Z = 48, R₁ = 2.5%; K[BF(CN)₃] P1¯, a = 6.519(1), b = 7.319(1), c = 7.633(2) Å, α = 68.02(3), β = 74.70(3), γ = 89.09(3)°, V = 324.3(1) ų, Z = 2, R₁ = 3.6%; Me₃SiNCBF(CN)₂ Pbca, a = 9.1838(6), b = 13.3094(8), c = 16.840(1) Å, V = 2058.4(2) ų, Z = 8, R₁ = 4.4%     

Atom Exchange Versus Reconstruction: (GexAs4−x)x− (x=2, 3) as Building Blocks for the Supertetrahedral Zintl Cluster [Au6(Ge3As)(Ge2As2)3]3−

The Zintl anion (Ge₂As₂)^2? represents an isostructural and isoelectronic binary counterpart of yellow arsenic, yet without being studied with the same intensity so far. Upon introducing [(PPh₃)AuMe] into the 1,2‐diaminoethane (en) solution of (Ge₂As₂)^2?, the heterometallic cluster anion [Au₆(Ge₃As)(Ge₂As₂)₃]^3? is obtained as its salt [K(crypt‐222)]₃[Au₆(Ge₃As)(Ge₂As₂)₃]?en?2 tol ( 1 ). The anion represents a rare example of a superpolyhedral Zintl cluster, and it comprises the largest number of Au atoms relative to main group (semi)metal atoms in such clusters. The overall supertetrahedral structure is based on a (non‐bonding) octahedron of six Au atoms that is face‐capped by four (Ge_xAs_4?x)^x? (x=2, 3) units. The Au atoms bind to four main group atoms in a rectangular manner, and this way hold the four units together to form this unprecedented architecture. The presence of one (Ge₃As)^3? unit besides three (Ge₂As₂)^2? units as a consequence of an exchange reaction in solution was verified by detailed quantum chemical (DFT) calculations, which ruled out all other compositions besides [Au₆(Ge₃As)(Ge₂As₂)₃]^3?. Reactions of the heavier homologues (Tt₂Pn₂)^2? (Tt=Sn, Pb; Pn=Sb, Bi) did not yield clusters corresponding to that in 1 , but dimers of ternary nine‐vertex clusters, {[AuTt₅Pn₃]₂}^4? (in 2 – 4 ; Tt/Pn=Sn/Sb, Sn/Bi, Pb/Sb), since the underlying pseudo‐tetrahedral units comprising heavier atoms do not tend to undergo the said exchange reactions as readily as (Ge₂As₂)^2?, according to the DFT calculations.     

Segregation and Stability in Surface Alloys: PdxRu1−x/Ru(0001) and PtxRu1−x/Ru(0001)

The stability of PdRu/Ru(0001) and PtRu/Ru(0001) surface alloys and the tendency for surface segregation of Pd and Pt subsurface guest metals in these surface alloys is studied by scanning tunneling microscopy (STM) and Auger electron spectroscopy (AES). Atomic resolution STM imaging and AES measurements reveal that upon overgrowing the surface alloys with a 1–2 monolayer Ru film and subsequent annealing to the temperatures required for initial surface alloy formation, the Ru‐covered Pd (Pt) atoms float back to the outermost layer. The lateral distribution of these species is also essentially identical to that of the initial surface alloys, before overgrowth by Ru. In combination, this clearly demonstrates that the surface alloys represent stable surface configurations, metastable only towards entropically favored bulk dissolution, and that there is a distinct driving force for surface segregation of these species. Consequences of these data on the mechanism for surface alloy formation are discussed.     

Die Reaktion der Zweikomponentensysteme P(OR)3 − x(NR2)x (x = 0–3)/CCl4 und P4/CCl4 mit HF-Donatoren

Reaction of the Two-component Systems P(OR)_{3 ? x}(NR₂)_x (x = 0–3)/CCl₄ and P₄/CCl₄ with HF-Donators The combination of organylammonium fluorides and carbon tetrachloride is a good agent for oxidative fluorination of trivalent phosphorus compounds. As oxidation products [(RO)PF₅]^? and (RO)₂P(O)F are obtained from P(OR)₃, (Et₂N)₂P(O)F and (Et₂N)₂(EtO)PF₂ from P(OEt)(NEt₂)₂ as well as (Et₂N)₃PF₂ and [(Et₂N)₃PF]⁺ from P(NEt₂)₃. In the system R₂NH/CCl₄/Et₃N · n HF P₄ is fast oxidized forming [HPF₅]^?, R₂NH · PF₅ and (R₂N)₂P(O)F. In the case of simultaneous addition of alcohols [(RO)PF₅]^?, (RO)₃PO and (R₂N)₂P(O)F are formed. The reactions are controlled by the nucleophilic power and the concentration of fluoride, the acidity of the system, and the temperature.