Zn11Rh18B8 and Zn10MRh18B8 with M = Sc,Ti, V,Cr, Mn,Fe, Co,Ni, Cu,Al, Si,Ge, Sn – New Ternary and Quaternary Zinc Rhodium Borides

Zn₁₁Rh₁₈B₈ and Zn₁₀MRh₁₈B₈ with M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Al, Si, Ge and Sn are obtained by reaction of the elemental components in sealed tantalum tubes at 1500 K. They crystallize tetragonally with Z = 2 in the spacegroup P4/mbm with lattice constants a = 1771.2(2) pm, c = 286.40(4) pm for Zn₁₁Rh₁₈B₈ and in the range a = 1767.65(9) pm, c = 285.96(3) pm (Zn₁₀NiRh₁₈B₈) to a = 1774.04(9) pm, c = 286.79(2) pm (Zn₁₀SnRh₁₈B₈) for the quaternary compounds. According to powder photographs all compounds are isotypic. Struture determinations based on single crystal X-ray data were performed with Zn₁₁Rh₁₈B₈, Zn₁₀FeRh₁₈B₈ and Zn₁₀NiRh₁₈B₈. The structure of Zn₁₁Rh₁₈B₈ is related to the Ti₃Co₅B₂ type. Along the short axis planar nets of rhodium atoms composed of triangles, squares, pentagons and elongated hexagons alternate with layers containing the boron and zinc atoms. The rhodium atoms form trigonal prisms centered by boron atoms, two kinds of tetragonal and pentagonal prisms centered by zinc atoms and elongated hexagonal prisms containing pairs of zinc atoms. In the quaternary compounds Zn₁₀MRh₁₈B₈ the zinc atoms in one sort of tetragonal prisms are replaced by M atoms.     

Acetamidiniumhexafluorometallate von Aluminium,Gallium, Indium,Vanadium, Chrom,Mangan, Eisen und Cobalt

Acetamidiniumhexafluorometallates of Aluminium, Gallium, Indium, Vanadium, Chromium, Manganese, Iron and Cobalt The title compounds were crystallized from F-containing aqueous solutions of their hexafluoro-metallate acids by adding acetamidine. Their unit cells were determined and the thermal decomposition was investigated thermoanalytically. The crystal structure of [CH₃C(NH₂)₂]₃AlF₆ was determined: Space group P4₁2₁2/P4₃2₁2, a = 8,987(1), c = 17,894(3) Å, R = 0,054. The unit cell parameters: .     

Electrochemical Reduction of Pentafluorophenylxenonium, -diazonium, -iodonium, -bromonium,and -phosphonium Salts

Cyclic voltammetry measurements on pentafluorophenylonium compounds of [C₆F₅X]⁺ Y^– type with X = Xe, N₂, C₆F₅Br, C₆F₅I, and (C₆F₅)₃P were carried out. In these series [C₆F₅Xe]⁺ shows the lowest and [(C₆F₅)₄P]⁺ the highest reduction potential. One electron reduction of [C₆F₅Xe]⁺ and [C₆F₅N₂]⁺ followed by the loss of Xe or N₂, respectively, leads to the generation of the [C₆F₅] ^· radical. Favoured following reactions of the [C₆F₅] ^· radical are the abstraction of hydrogen from MeCN or dimerisation. After the first reduction step the other onium cations split off the pentafluorophenyl element molecule such as (C₆F₅)₃P, C₆F₅Br, or C₆F₅I, respectively. These molecules undergo further reductions. The low reduction potential of [C₆F₅Xe]⁺ is in contrast to former measurements on partially fluorinated or chlorinated phenylxenonium cations. A plausible explaination for the different behaviour of these Xe–C compounds in electrochemical reduction processes is given.     

Quaternäre Magnesium-Iridiumboride Mg2Xlr5B2 mit X = Be,Al, Si,P, Ti,V, Cr,Mn, Fe,Co, Ni,Cu, Zn,Ga, Ge,As – eine Besetzungsvariante des Ti3Co5B2-Typs

Quaternary Magnesium Iridium Borides Mg₂XIr₅B₂ with X = Be, Al, Si, P, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As – a Substitution Variant of the Ti₃Co₅B₂ Type of Structure The compounds Mg₂XIr₅B₂ with X = Be, Al, Si, P, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge and As crystallize tetragonally with Z = 2 in the space group P4/mbm. The lattice constants are in the range a = 9.199 Å, c = 2.880 Å for Mg₂BeIr₅B₂ und a = 9.406 Å, c = 2.953 Å for Mg₂TiIr₅B₂ (further lattice constants are given in Table 1). X-ray structure determinations carried out with single crystals of the Si-and the P-compounds showed that a substitution variant of the Ti₃Co₅B₂ type of structure is formed. According to X-ray powder photographs the other compounds are isotypic. In the compounds with X = P and As the X-siteset is only occupied at about 70% and 80% respectively.     

Neues über Hexafluoromanganate(IV). MIIMnF6 mit M=Mg,Ca, Zn,Cd, Hg,Ni, Cu,Ag

Newly obtained are NiMnF₆ (ochre-yellow) and ZnMnF₆ (orangeyellow), both VF₃-type [a = 4.91₀, c = 13.16₉ Å (Ni); a = 4.96₆, c = 13.29₃ Å (Zn)], as well as CdMnF₆ (yellow) and HgMnF₆ (orange), both of LiSbF₆ type [a = 5.08₇, c = 14.00₇ Å (Cd); a = 5.08₄, c = 14.12₅ Å (Hg)]. CuMnF₆ (copper-red) and AgMnF₆ (blackbrown) show complicated powder diagrams. MgMnF₆ and CaMnF₆ belong to the LiAbF₆ type, too [Guinier-photographs].     

First-principles Density Functional Theory Elucidation of the Hydrogen Evolution Reaction on TM-promoted TiC2 (TM=Fe,Co, Ni,Cu, Ru,Rh, Pd,Ag, Os,Ir, Pt,and Au)

Single-atom-catalyst-based systems have been attractive by virtue of their desirable catalytic performance. Herein, the possibility of the 15 transition-metal (TM)-promoted (TM=Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Cd, Os, Ir, Pt, Au, and Hg) and their hydrogen evolution reaction (HER) performance were investigated on two-dimensional titanium carbides (TiC₂). It is found that the adsorption strength of TMs on TiC₂ is stronger than that of TMs on γ-graphyne and weaker than that of TMs on Ti₃C₂. Among the fifteen investigated catalysts, Ru−TiC₂, Ag−TiC₂, Ir−TiC₂, Au−TiC₂, and Fe−TiC₂ exhibits overpotential of −0.18, −0.15, −0.18, −0.17, and −0.04 V, respectively. In addition, the Volmer-Tafel step was preferred to the Volmer-Heyrovsky step on Fe−TiC₂. This work suggests that Fe−TiC₂ is possibly a superior HER electrocatalyst.     

Fluoride mit zweiwertigem Silber. Zur Kenntnis der Verbindungen AgII[MF6] mit M = Ge,Sn, Pb,Ti, Zr,Hf, Rh,Pd, Pt.

Fluorides with divalent Silver. On the compounds Ag^II[MF₆] with M = Ge, Sn, Pb, Ti, Zr, Hf, Rh, Pd, Pt. For the first time AgTiF₆, AgGeF₆, AgSnF₆ AgPbF₆ (all light-blue), AgRhF₆ (black), AgPdF₆ (d.brown), AgPtF₆ (brownviolet) as well as AgZrF₆ and AgHfF₆ (both deeply blueviolet) are prepared. AgSnF₆, AgPbF₆ and AgPdF₆ obey the Curie-Weiss Law (m? = 2,0 m?_B, small θ-value). In the case of AgZrF₆ and AgHfF₆ there is a strong magnetic exchange between Ag²⁺ ions; this may be the cause for the unexpected deep colour.     

Polymorphism of the bivalent metal vanadates MeV2O6 (Me = Mg,Ca, Mn,Co, Ni,Cu, Zn,Cd)

Based on the literature data, our former findings and additional DTA and high-temperature X-ray studies performed for CdV₂O₆, MgV₂O₆, and MnV₂O₆, a consistent scheme of the phase transformations of the MeV₂O₆ (Me = Mg, Ca, Mn, Co, Ni, Cu, Zn, Cd) metavanadates is constructed at normal pressure between room temperature and melting points. Three types of structures exist for the considered compounds: brannerite type (B), pseudobrannerite type (P), and NiV₂O₆ type (N). The following phase transformations have been observed: Me = Mg, B → P at 535°C; Me = Mn, B → P at 540°C; Me = Co, N → B at 660°C; Me = Cu, B (with triclinic distortion) → B at 625°C (secondary order); and Me = Cd, B → P at 170°. CaV₂O₆P, NiV₂O₆N, and ZnV₂O₆B exist in unique form in the entire temperature range. P-form seems to be favored by Me of larger ionic radii. N-form seems to appear at a peculiar d-shell structure and small Me size. Preliminary explanation of the dependence of the structure type on Me size is offered. New X-ray data are given for CdV₂O₆B, CdV₂O₆P, MgV₂O₆B, MgV₂O₆P, and MnV₂O₆P.     

Zur Kenntnis der RbNiCrF6Typs. III. Neue Fluoride des Typs CsZnMF6 mit M = Al,Ga, In,Tl, Sc,Ti, V,Mn, Cu,Rh

On the RbNiCrF₆ Type. III. New Fluorides of the Type CsZnMF₆ (M = Al, Ga, In, Tl, Sc, Ti, V, Mn, Cu, Rh) Cubic compounds are CsZnGaF₆ [3] (colourless, a = 10.29 Å); CsZnInF₆ (colourless, a = 10.58 Å); CsZnTlF₆ (colourless, a = 10.62 Å); CsZnScF₆ (colourless, a = 10.58 Å); CsZnTiF₆ (lightblue, a = 10.50 Å); CsZnVF₆ (lightgreen, a = 10.43 Å); CsZnMnF₆ (redbrown, a = 10.40 Å); CsZnCuF₆ (light brown, a = 10.24 Å); CsZnRhF₆ (redbrown, a = 10.41 Å), all RbNiCrF₆ type of structure, in addition non cubic: CsZnAlF₆ (colourless). The Madelung part of lattice energy, MAPLE, is calculated and discussed.     

Ternary metal borides [La,Ce,Pr,Nd,Sm] Os4B4 and [Y,La,Ce,Pr,Nd,Sm,Gd,Tb] Ir4B4 with NdCo4B4-type structure

New ternary metal borides with compositionR. E. T ₄B₄ (R. E.=rare earth metal,T=transition metal) have been synthesized within the systems [La,Ce,Pr,Nd,Sm]–Os–B and [Y, La, Ce, Pr, Nd, Sm, Gd, Tb]–Ir–B. All compounds were found to be crystallizing with NdCo₄B₄-type structure. Magnetic measurements (80–300 K,Curie-Weiss behaviour, _p ~ 16K and µ_eff=9.94µ_B for TbIr₄B₄) indicate Y andR. E. elements (except Ce) to be trivalent in these compounds. The crystal chemistry of the isotypic series [Y,R. E.] [Os,Ir]₄B₄ is discussed.

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Ternäre Metallboride. [La,Ce,Pr,Nd,Sm] Os₄B₄ und [Y,La,Ce,Pr,Nd,Sm,Gd,Tb] Ir₄B₄ mit NdCo₄B₄-Struktur

Zusammenfassung Es wurden neue Metallboride der ZusammensetzungR. E. T ₄B₄ (R. E.=Seltenerdmetall,T=Übergangsmetall) innerhalb der Systeme [La,Ce, Pr,Nd,Sm]–Os–B und [Y,La,Ce,Pr,Nd,Sm,Gd,Tb]–Ir–B hergestellt. Alle Verbindungen kristallisieren entsprechend dem NdCo₄B₄-Typ. Magnetische Messungen (80–300K,Curie-Weiss-Verhalten, _p ~ 16K und µ_eff=9.94µ_B für TbIr₄B₄) zeigen an daß Y und dieR. E.-Elemente (ausgenommen Ce) in diesen Verbindungen trivalent sind. Die Kristallchemie der isotypen [Y,R. E.][Os,Ir]₄B₄-Verbindungen wird diskutiert.

     

Structure and Polymorphism of M(thd)3 (M = Al,Cr, Mn,Fe, Co,Ga, and In)

Formation, crystal structure, polymorphism, and transition between polymorphs are reported for M(thd)₃, (M = Al, Cr, Mn, Fe, Co, Ga, and In) [(thd)^– = anion of H(thd) = C₁₁H₂₀O₂ = 2, 2, 6, 6‐tetramethylheptane‐3, 5‐dione]. Fresh crystal‐structure data are provided for monoclinic polymorphs of Al(thd)₃, Ga(thd)₃, and In(thd)₃. Apart from adjustment of the M–O_k bond length, the structural characteristics of M(thd)₃ complexes remain essentially unaffected by change of M. Analysis of the M–O_k, O_k–C_k, and C_k–C_k distances support the notion that the M–O_k–C_k–C_k–C_k–O_k– ring forms a heterocyclic unit with σ and π contributions to the bonds. Tentative assessments according to the bond‐valence or bond‐order scheme suggest that the strengths of the σ bonds are approximately equal for the M–O_k, O_k–C_k, and C_k–C_k bonds, whereas the π component of the M–O_k bonds is small compared with those for the O_k–C_k, and C_k–C_k bonds. The contours of a pattern for the occurrence of M(thd)₃ polymorphs suggest that polymorphs with structures of orthorhombic or higher symmetry are favored on crystallization from the vapor phase (viz. sublimation). Monoclinic polymorphs prefer crystallization from solution at temperatures closer to ambient. Each of the M(thd)₃ complexes subject to this study exhibits three or more polymorphs (further variants are likely to emerge consequent on systematic exploration of the crystallization conditions). High‐temperature powder X‐ray diffraction shows that the monoclinic polymorphs convert irreversibly to the corresponding rotational disordered orthorhombic variant above some 100–150 °C (depending on M). The orthorhombic variant is in turn transformed into polymorphs of tetragonal and cubic symmetry before entering the molten state. These findings are discussed in light of the current conceptions of rotational disorder in molecular crystals.     

Bromination of silatranyl-, germatranyl-, silyl-, and germyl-phenylacetylenes

Reactions of element-substituted alkynes R₃MCCPh (R₃M = Me₃Si, Et₃Si, Ph₃Si, Et₃Ge, n-Bu₃Sn, N(CH₂CH₂O)₃Si, N(CH₂CH₂O)₃Ge, N(CH₂-CHMeO)₃Ge, and N(CH₂CH₂O)₂(CH₂CHPhO)Ge) with bromine, tetra-n-butylammonium tribromide (TBAT), and N-bromosuccinimide (NBS)/DMSO were investigated. The Z,E-ratio of isomeric dibromoalkenes formed in bromination reaction with Br₂ and TBAT are discussed. The crystal structures of N(CH₂CH₂O)₃SiCCPh and N(CH₂CHMeO)₃GeX (X = C CPh, C(Br)C(Br)Ph, C(Br₂)C(O)Ph), and Ph₃SiC(Br)C(Br)Ph are reported. © 2003 Wiley Periodicals, Inc. 15:43–56, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/.hc10211     

Organoborane Chemistry : by Thomas ONak,Academic Press,New York and London, 1975, x + 360 pages, $38, £18.25.

Methyl iodide reacts with Pt₂(μ-SMe)₂Ph₂(PMe₂Ph)₂ to give PtIPh(SMe₂)(PMe₂Ph) and with Pt₂(μ-SMe)₂Me₂(PMe₂Ph)₂ to give PtI₂Me₂(SMe₂)(PMe₂Ph) via an isolable intermediate Pt₂I₂(μ-SMe)₂Me₄(PMe₂Ph)₂. The mechanisms of the reactions are discussed.     

On the Perovskites Ba2LnSbO6 (Ln = Nd,Sm, Eu,Gd, Tb,Dy, Ho,Er, Yb)

Polycrystalline Ba₂LnSbO₆ (Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) are cubic, perovskite-type compounds, space group Fm3m (No. 225), Z = 4, with a values from a = 8.544(2) Å for Ba₂NdSbO₆ to a = 8.368(1) Å for Ba₂YbSbO₆. X-ray diffraction data for all the compounds and the results of magnetic measurements for two of them are given.     

Über Neue Hexafluororhodate(IV): AIIRhIVF6 (AII = Ba,Sr, Ca,Mg, Zn,Cd, Hg,Ni sowie Cu)

On Novel Hexafluoro Rhodates(IV): A^IIRh^IVF₆. (A^II = Ba, Sr, Ca, Mg, Zn, Cd, Hg, Ni, Cu) We obtained hithertoo unknown BaRhF₆ and SrRhF₆ (both lemon yellow) of (hexag.) BaSiF₆?Type [a = 7.37₉, c = 7.21₁Å bzw. a = 7.15₇, c = 6.94₈ Å] as well as CaRhF₆ (light yellow) [a = 5.26₇, c = 14.61₂ Å], MgRhF₆ (light yellow) [a = 5.02₇, c 13.51₁Å], ZnRhF₅ (light yellow) [a = 4.99₆, c = 13.68₃ Å], CdRhF₆ (light yellow) [a = 5.,12₈ c = 14.44₇ Å], HgRhF₆ (orange) [a = 5.13₃, c = 14.67₆ Å], NiRhF₆ (light brown) [a = 4.96₀, c = 13.51₄ Å] all of (hexag.) LiSbF₆?type. The strukture of CuRhF₆ (light brown) is yet unknown.     

Fluorides of Copper,Silver, Gold,and Palladium

Fluorine, by far the most reactive of the non-metals, is capable of forming a large number of compounds with nearly all other elements (exceptions (so far): He, Ne, and Ar), even under comparatively “mild” reaction conditions. These compounds usually differ markedly from those of the heavier halogens in composition, structure, and chemical and physical properties. Thus, for example, it is generally quite easy to prepare fluorides containing elements in high oxidation states (often their maximum), as in AgF₂, CsAgF₄, PdF₃, CsAuF₆ etc., whereas the corresponding chlorides, bromides or iodides are in many cases (still) unknown. Conversely, the synthesis of fluorides containing these elements in middle or low oxidation states often meets with considerable difficulty, even where it is possible at all, as, e.g., in the case of CuF, AuF, PtF₂, SeF₂. Finally, there are also some examples of compounds MX_n, which with X = F are stable, but with X = Cl are unstable or decompose easily (e.g. CoF₃/CoCl₃, VF₄/VCl₄, PbF₄/PbCl₄, AsF₅/AsCl₅). Consequently, fluorine compounds are of great general interest.     

Synthesis,Characterization, and Crystal Structures of Cu,Ag, and Pd Dinitramide Salts

The literature known, but not fully characterized, silver dinitramide transfer reagents AgN(NO₂)₂ ( 1 ), [Ag(NCCH₃)][N(NO₂)₂] ( 2 ), and [Ag(py)₂][N(NO₂)₂] ( 3 ) have been investigated by ¹⁰⁹Ag, ¹⁴N NMR and vibrational spectroscopy (IR, Raman). In addition, the poorly understood [Cu(NH₃)₄][N(NO₂)₂)]₂ ( 4 ) and [Pd(NH₃)₄][N(NO₂)₂]₂, ( 5 ) have also been prepared and characterized by ¹⁴N NMR and vibrational spectroscopy (IR, Raman). The structures of 2 — 5 have also been determined by X‐ray diffraction.     

[Boranato-bis(dimethylphosphonium-methylid)]-Komplexe der do- und d10-Metalle: Li,Be, Mg,Zn, Cd,Hg, Al und Ga

Dehydrohalogenation and metallation of boranato-bis-trimethylphosphonium salts (1), using two equivalents of a lithiumalkyl in tetrahydrofuran, leads to a solvated organolithium reagent H₂B[(CH₃)₂PCH₂]₂Li (3) which can be converted into a 1:1n1-complex with tetramethylethylenediamin (4).3 reacts with anhydrous metal(II) halides to form spirocyclic coordination compounds of the type H₂B[(CH₃)₂PCH₂]₂ M[CH₂P(CH₃)₂]₂BH₂ (5–9,M=Be, Mg, Zn, Cd, Hg). The reaction of [(CH₃)₃PBH₂P(CH₃)₃]Br (1) with lithium tetramethylmetalates Li[M(CH₃)₄],M=Al, Ga, on heating in the absence of a solvent affords the metallocycles H₂B[(CH₃)₂PCH₂]₂ M(CH₃)₂ (10, 11) with evolution of methane. The products can be sublimed from the reaction mixture. The proposed structures of the new compounds, with tetrahedrally coordinated central atoms and strong covalent metal-carbon interactions, are supported by mass, IR and¹H,⁷Li,¹¹B,¹³C, and³¹P NMR spectra. Compound9 represents a rare case of a tetracoordinate organomercurial, compound5 is the first nonionic tetraalkylberyllate.

     

Der chemische Transport von Cu,Ag, Au,Ru, Rh,Pd, Os,Ir, Pt unter Mitwirkung von Gaskomplexen. Al2Cl6, Fe2Cl6 oder Al2J6 als Komplexbildner

The Chemical Transport of Cu, Ag, Au, Ru, Rh, Pd, Os, Ir, Pt in the Presence of Al₂Cl₆, Fe₂Cl₆ or Al₂I₆, Causing Complex Formation Chemical transport experiments show, that the title elements (with exception of Os) in the presence of halide forming agents (HCl, Cl₂ or I₂ resp.) and of complex forming agents (Al₂Cl₆, Fe₂Cl₆ or Al₂I₆ resp.) give gaseous complex compounds with a remarkable stability. This leads to novel possibilities for the chemical transport of the elements and their compounds. The effect of complex formation can be predicted on the basis of qualitative thermodynamic considerations. The corrosion of the wall of the quartz ampoule at temperatures above 600°C by Al₂Cl₆/AlCl₃ is avoidable by the usage of Fe₂Cl₆/FeCl₃ instead of Al₂Cl₆/AlCl₃. Experiments in the system Pd/I₂, Al₂I₆ lead to the formation of crystals of Pd₂Al.