Tetrafluoroaurate(III) der Lanthaniden M2F[AuF4]5 (M = Tb,Dy, Ho,Er)

Tetrafluoroaurates(III) of Lanthanoides M₂F[AuF₄]₅ (M = Tb, Dy, Ho, Er) Tetrafluoroaurates(III) M₂F[AuF₄]₅ with M = Tb, Dy, Ho, Er, all yellow, have been obtained. From single crystal data they crystallize triclinic, space group P1 -C¹_i (No. 2) with Tb: a = 1 194,34(7) pm, b = 798,46(6) pm, c = 902,02(7) pm, α = 89,033(7)°, β = 88,990(6)°, γ = 89,006(7)°; Dy: a = 1 191,66(9) pm, b = 796,33(8) pm, c = 899,65(9) pm, α = 88,956(8)°, β = 89,056(8)°, γ = 88,972(8)°; Ho: a = 1 189,06(10) pm, b = 795,46(6) pm, c = 896,81(7) pm, α = 88,912(8)°, β = 89,101(7)°, γ = 88,873(8)°; Er: a = 1 185,20(40), b = 793,98(14), c = 893,83(20), α = 88,751(23)°, β = 89,187(26)°, γ = 88,884(9)°     

Synthese und Struktur neuer Tetrafluoroaurate(III), TlF2[AuF4], M2F[AuF4]5 (M = Bi,La, Y) und Sm[AuF4]3

Synthesis and Structure of Tetrafluoroaurates(III), TlF₂[AuF₄], M₂F[AuF₄]₅ (M = Y, La, Bi), Sm[AuF₄]₃ with an Appendix on Sm[AuF₄]₂ In the system MF₃/AuF₃ the structures of several yellow Tetrafluoroaurates(III) have been determinated. TlF₂[AuF₄] crystallizes tetragonal, space group P4₁2₁2 – D (Nr. 92) with a = 573.17(4) pm, c = 2780.4(3) pm, Z = 8; M₂F[AuF₄]₅ (M = Bi, La) tetragonal, space group P4₁2₁2 – D (Nr. 92) with a = 822.89(5) pm, c = 2557.1(3) pm, Z = 4 (Bi); with a = 836.80(3) pm, c = 2602.2(2) pm, Z = 4 (La); Y₂F[AuF₄]₅ monoclin, space group P2/n – C (Nr. 13) with a = 1188.9(3) pm, b = 797.4(2) pm, c = 895.7(3) pm, β = 89.18(3), Z = 4 and Sm[AuF₄]₃ trigonal, space group R3c – D (Nr. 167) with a = 1034.5(1) pm, c = 1614.1(3) pm, Z = 6. All these yellow crystals have been obtained by solid state reactions in autoclaves or sealed goldtubes.     

The former "C60F16" is actually a double-caged adduct: (C60F16)(C60)

X-ray diffraction study of the substance originally believed to be C(60)F(16) reveals a double-caged structure, (C(60)F(16))(C(60)); MALDI mass spectra, 19F NMR spectral data and reasons for stability are discussed.     

Atmospheric chemistry of n-C(x)F(2)(x)(+1)CHO (x = 1, 2, 3, 4): fate of n-C(x)F(2)(x)(+1)C(O) radicals

Smog chamber/FTIR techniques were used to study the atmospheric fate of n-C(x)F(2)(x)(+1)C(O) (x = 1, 2, 3, 4) radicals in 700 Torr O(2)/N(2) diluent at 298 +/- 3 K. A competition is observed between reaction with O(2) to form n-C(x)()F(2)(x)()(+1)C(O)O(2) radicals and decomposition to form n-C(x)F(2)(x)(+1) radicals and CO. In 700 Torr O(2)/N(2) diluent at 298 +/- 3 K, the rate constant ratio, k(n-C(x)F(2)(x)(+1)C(O) + O(2) --> n-C(x)F(2)(x)(+1)C(O)O(2))/k(n-C(x)F(2)(x)(+1)C(O) --> n-C(x)F(2)(x)(+1) + CO) = (1.30 +/- 0.05) x 10(-17), (1.90 +/- 0.17) x 10(-19), (5.04 +/- 0.40) x 10(-20), and (2.67 +/- 0.42) x 10(-20) cm(3) molecule(-1) for x = 1, 2, 3, 4, respectively. In one atmosphere of air at 298 K, reaction with O(2) accounts for 99%, 50%, 21%, and 12% of the loss of n-C(x)F(2)(x)(+1)C(O) radicals for x = 1, 2, 3, 4, respectively. Results are discussed with respect to the atmospheric chemistry of n-C(x)F(2)(x)(+1)C(O) radicals and their possible role in contributing to the formation of perfluorocarboxylic acids in the environment.     

Theoretical Exploration of Stereochemical Nonrigidity for RfCo（PF3）x（CO）4-x（Rf=CF3, C2F5, C3F7, x=0-4）

The stereochemical nonrigidity of RfCo（PF3）x（CO）4-x（Rf=CF3,C2F5,C3F7,x=0-4） was studied at the theoretical level of B3LYP/6-31 1＋G^＊ via Gaussian 09.The intramolecular rearrangements in these penta-coordinated compounds are mainly caused by the vibrations of perfluoroalkyl groups.All the barriers along the reaction coordinate are less than 66.9 kJ/mol,which indicates that the rearrangements are kinetically favorable and hard to elucidate by experiment.Besides,ligand PF3 is a ligand similar to CO,the energy difference between the reactant and product is small.     

Synthesen und Eigenschaften von Tetrakis(perfluoralkyl)tellur Te(Rf)4 (Rf = CF3, C2F5, C2F5, C3F7, C4F9)

Synthesis and Properties of Tetrakis(Perfluoroalkyl)Tellurium Te(R_f)₄ (R_f = CF₃, C₂F₅, C₃F₇, C₄F₉) Te(CF₃)₄ is obtained from the reaction of Te(CF₃)Cl₂ with Cd(CF₃)₂ complexes as a complex with e. g. CH₃CN, DMF. It is a light and temperature sensitive hydrolysable liquid. The reaction with fluorides yields the complex anion [Te(CF₃)₄F]⁻, with fluoride ion acceptors the complex cation [Te(CF₃)₃]⁺. With traces of water an acidic solution is formed. Te(CF₃)₄ acts as a trifluoromethylation reagent. The reaction with XeF₂ gives hints for the formation of Ye(CF₃)₄F₂. Properties and NMR spectra are discussed. The much more stable complexes of Te(R_f)₄ (R_f = C₂F₅, C₃F₇, C₄F₉) are formed from the reaction of TeCl₄ with the corresponding Cd(R_f)₂ complexes.     

Perfluororganotellur-Verbindungen: Neue Untersuchungen zur Darstellung von Te(Rf)2 und CH3TeRf (Rf = C2F5, C3F7, C6F5)

Perfluoroorgano Tellurium Compounds: New Investigations on the Preparation of Te(R_f)₂ and CH₃TeR_f (R_f = C₂F₅, C₃F₇, C₆F₅) Methyl(perfluoroorgano) tellurium and bis(perfluoroorgano) tellurium compounds are synthesized in high yields from the photochemical or the thermal reactions of (CH₃)₂ Te with perfluoroorgano iodides in the presence of (C₂H₅)₃N. They are isolated in pure states. Another general method for the preparation of bis(perfluoroorgano) tellurium is the thermal reaction of TeCl₄ with bis(perfluoroorgano) mercury. The preparations and properties of the partially new compounds are described.     

Binuclear homoleptic manganese carbonyls: Mn2(CO)x (x = 10, 9, 8, 7)

The unsaturated homoleptic manganese carbonyls Mn(2)(CO)(n)() (n = 7, 8, 9) are characterized by their equilibrium geometries, thermochemistry, and vibrational frequencies using methods from density functional theory (DFT). The computed metal-metal distances for global minima range from 3.01 A for the unbridged Mn(2)(CO)(10) with a Mn-Mn single bond to 2.14 A for a monobridged Mn(2)(CO)(7) formulated with a metal-metal quadruple bond. The global minimum for Mn(2)(CO)(9) has a four-electron bridging mu-eta(2)-CO group and a 2.96 A Mn-Mn distance suggestive of the single bond required for 18-electron configurations for both metal atoms. This structure is closely related to an experimentally realized structure for the isolated and structurally characterized stable phosphine complex [R(2)PCH(2)PR(2)](2)Mn(2)(CO)(4)(mu-eta(2)-CO). An unbridged (OC)(4)Mn-Mn(CO)(5) structure for Mn(2)(CO)(9) has only slightly (<6 kcal/mol) higher energy with a somewhat shorter metal-metal distance of 2.77 A. For Mn(2)(CO)(8) the lowest energy structure is a D(2)(d)() unbridged structure with a 2.36 A metal-metal distance suggesting the triple bond required for the favored 18-electron configuration for both metal atoms. However, the unbridged unsymmetrical (CO)(3)Mn-Mn(CO)(5) structure with a metal-metal bond distance of 2.40 A lies only 1 to 3 kcal/mol above this global minimum. The lowest energy structure of Mn(2)(CO)(7) is an unbridged C(s)() structure with a short metal-metal distance of 2.26 A. This is followed energetically by another C(s)() unbridged Mn(2)(CO)(7) structure with a somewhat longer metal-metal distance of 2.38 A.     

Electron correlation effects at semiconductor surfaces and interfaces: Si(111)-5x5, Si(111)-7x7 and Sn/Ge(111)

Electron correlation effects associated with the dangling bond surface states of Si(111)-5×5, Si(111)-7×7 and Sn/Ge(111)-3×3 are analyzed. In all the cases, extensive LDA-calculations are performed and effective two-dimensional Hamiltonians are deduced. Our analysis of these Hamiltonians shows that: (a) the Si(111)-5×5 surface states exhibits a metal-insulator transition; (b) the Si(111)-7×7 surface shows important similarities with the Si(111)-5×5 case, but it has a dangling bond surface band having a metallic character; (c) finally, the Sn/Ge(111)-3×3 dangling bond surface bands also shows important correlation effects that are found, however, not to affect the metallic character of the surface bands.     

Th2F7[AuF4] – das erste „fluorobasische”︁ Tetrafluoroaurat(III) im System ThF4/AuF3

Th₂F₇[AuF₄] – the First Fluoroaurate in the System MF₄/AuF₃ We observed for the first time single crystals of Th₂F₇[AuF₄] [1] in attempts to synthesize ternary fluoroaurates with tetravalent cations. Concerning to X‐Ray‐data (Mo–Kα), the light‐yellow compound crystallizes tetragonal in the space group I4/mcm (No. 140) with a = 1130.6(1) pm, c = 631.34(7) pm and Z = 4.     

Syntheses and Characterization of (C2F5)3BCO and (C3F7)3BCO

The new tris(perfluoroalkyl)borane carbonyls, (C₂F₅)₃BCO and (C₃F₇)₃BCO, were prepared by means of a novel synthetic route using commercially available precursors by reacting K[(C₂F₅)₃BCOOH] and K[(C₃F₇)₃BCOOH] with concentrated sulfuric acid in the last step. The carboxylic acids, K[(C₂F₅)₃BCOOH] and K[(C₃F₇)₃BCOOH], were prepared by oxidative cleavage of the C?C triple bonds in Cs[(C₂F₅)₃BC?CPh] and Cs[(C₃F₇)₃BC?CPh] in a two‐step process to yield K[(C₂F₅)₃BCO? COPh] and K[(C₃F₇)₃BCO? COPh] as isolable intermediates. Crystal structures were obtained of K[(C₂F₅)₃BCO? COPh], K[(C₂F₅)₃BCOOH] ? H₂O, (C₂F₅)₃BCO, K[(C₃F₇)₃BCOOH] ? 2 H₂O, and (C₃F₇)₃BCO. In the crystal structures of (C₂F₅)₃BCO and (C₃F₇)₃BCO the C?O bond lengths are 1.109(2) and 1.103(5) Å, respectively, which are among the shortest observed to date. Tris(pentafluoroethyl)borane carbonyl and (C₃F₇)₃BCO slowly decompose at room temperature to yield CO, difluoroperfluoroalkylboranes and perfluoroalkenes. The decomposition of (C₂F₅)₃BCO was found to follow a first‐order rate law with E_a=107 kJ mol^?1.     

Synthese und Eigenschaften von Diethyldithiocarbaminsäureperfluororganylestern, (C2H5)2NC(S)SRf (Rf = CF3, C2F5, i‐C3F7, n‐C4F9, C6F5)

Syntheses and Properties of Perfluoroorgano Esters of the Diethyldithiocarbamic Acid, (C₂H₅)₂NC(S)SR_f (R_f = CF₃, C₂F₅, i‐C₃F₇, n‐C₄F₉, C₆F₅) Tetraethylthiuram disulfide reacts under different conditions with perfluoroorgano silver(I), AgR_f, and perfluoroorgano cadmium compounds, Cd(R_f)₂, to give the corresponding perfluoroorgano esters of diethyldithiocarbamic acid, (C₂H₅)₂NC(S)SR_f (R_f = CF₃, C₂F₅, i‐C₃F₇, n‐C₄F₉, C₆F₅), and metal diethyldithiocarbamates, AgSC(S)N(C₂H₅)₂ and Cd[SC(S)N(C₂H₅)₂]₂. The mechanisms of the reactions with AgR_f and Cd(R_f)₂ are discussed.     

Theoretical probing of deltahedral closo-auroboranes B(x)Au(x)2- (x = 5-12)

Using density functional theory calculations, here we show that a series of B(x)Au(x)2- (x = 5-12) dianions possesses structure and bonding similar to the famous deltahedral closo-borane cages, B(x)H(x)2-. Effective atomic charges on Au in B(x)Au(x)2- are very similar to those on H in B(x)H(x)2-, indicating that Au in the closo-auroboranes is indeed analogous to H in the closo-boranes. The present theoretical predictions of B(x)Au(x)2- suggest that the closo-auroborane species are viable new chemical building blocks that may be synthesized in bulk. The Au atoms in the closo-auroboranes represent highly atomically dispersed Au and may potentially exhibit novel catalytic and chemical properties.     

The preparations and properties of tris(perfluoroorgano)bismuth compounds Bi(Rf)3 (Rf = CF3, C2F5, n-C3F7, n-C4F9, n-C6F13, n-C8 F17, C6F5)

Tris(perfluoroorgano)bismuth compounds Bi(R_f)₃ (R_f = CF₃, C₂F₅, n-C₃F₇, n-C₄F₉, n-C₆F₁₃, n-C₈F₁₇, C₆F₅) are easily prepared in high yields from the reactions of perfluoroorganocadmium complexes with BiCl₃, or BiBr₃ in aprotic solvents. The perfluoroorganobismuth halides intermediates in these reactions have been detected by NMR spectroscopy.     

Zur Kristallstruktur von La[AuF4]3, dem Anfangsglied der Reihe M[AuF4]3−xFx (x = 0, 0,5 und 1)

On the Crystal Structure of La[AuF₄]₃, the Final Link in the Series M[AuF₄]_3?xF_x (x = 0, 0.5 and 1) Yellow La(AuF₄)₃ was prepared for the first time in form of single crystals and investigated by X-ray methods. It crystallizes in space group R3 c-D (Nr. 167) with a = 1056.2(2) pm, c = 1633.7(8) pm, Z = 6.     

Homologous Silver Bismuth Chalcogenide Halides (N,x)P. III. The (4, x)P, (5, x)P,and (7, x)P Structure Families of Modular Compounds with Tunable Composition and Structure

The crystal structures of six members of the homologous series with general formula [BiQX]₂[Ag_xBi_1?xQ_2?2xX_2x?1]_N+1 (Q = S, Se; X = Cl, Br; 1/2 ≤ x ≤ 1) and N = 4, 5, or 7 were determined by single‐crystal X‐ray diffraction. The series are characterized by the parameters N and x and are denoted ^{(N, x)}P. Ag₃Bi₄S₆Cl₃ (x = 0.60) (I) , Ag_3.5Bi_3.5S₅Br₄ (x = 0.70) (II) and Ag_3.65Bi_3.35Se_4.70Br_4.30 (x = 0.73) (III) belong to ^{(4, x})P series Ag_5xBi_7?5xQ_12?10xX_10x?3 and adopt the AgBi₆S₉ structure type. The ^{(5, x)}P compound Ag_3.66Bi_4.34S_6.68Br_3.32 (IV) , which corresponds to x = 0.61 in Ag_6xBi_8?6xS_14?12xBr_12x?4, crystallizes isostructurally to AgBi₃S₅. The compounds Ag_4.56Bi_5.44Se_8.88Br_3.12 (x = 0.57) (V) and Ag_5.14Bi_4.86S_7.76Br_4.24 (x = 0.64) (VI) , which are members of ^{(7, x)}P series Ag_8xBi_10?8xQ_18?16xBr_16x?6, adopt the Ag₃Bi₇S₁₂ structure type. In the monoclinic crystal structures (space group C2/m) two kinds of layered modules alternate along [001]. Modules of type A uniformly consist of paired rods of face‐sharing monocapped trigonal prisms around Bi atoms with octahedra around mixed occupied metal positions (M = Ag/Bi) between them. Modules of type B are composed of [MZ₆] octahedra, which are arranged in NaCl‐type fragments of thickness N. All structures exhibit Ag/Bi disorder in octahedrally coordinated metal positions as well as Q/X mixed occupation of some anion positions. Corresponding to their black color, all compounds are narrow‐gap semiconductors (E_g = 0.35 eV for (II) ). General characteristics of the entire class of ^{(N, x)}P compounds are gathered in a catalogue.     

Photon-stimulated desorption of F(-) ions from CF(3)Cl adsorbed on Si(111)-7x7

We report the photon-stimulated desorption of negative ions induced by direct dipolar dissociation and dissociative electron attachment. The photon-stimulated desorption of F(-) ions from CF(3)Cl physisorbed on a Si(111)-7x7 surface at 30 K in the photon energy range 12-35 eV was studied. The F(-) ion yield exhibits four resonances, at 12.8, 16.2, 19.5, and 22.3 eV, quite unlike the gas phase photodissociation cross section. The intensities of these resonances depend strongly on the CF(3)Cl coverage in a manner which varies from peak to peak. The resonances at 19.5 and 22.3 eV, which have a significant enhancement in the monolayer regime, are due to electron mediated dipolar dissociation of adsorbed CF(3)Cl molecules. The enhancement is attributed to surface electron attachment following molecular excitation. A significant enhancement in the monolayer regime has also been observed for the resonances at 12.8 and 16.2 eV. These two resonances are ascribable to a combination of electron mediated dipolar dissociation and dissociative electron attachment driven by photoelectrons generated in the neighboring molecules.     

The perfluorinated alcohols (F5C6)(F3C)2COH and (F5C6)(F10C5)COH: synthesis, theoretical and acidity studies, spectroscopy and structures in the solid state and the gas phase

The syntheses of the perfluorinated alcohols (F(5)C(6))(F(3)C)(2)COH (1) and (F(5)C(6))(C(5)F(10))COH (2) are described. Both compounds were prepared in reasonable yields (1: 65%, 2: 85%) by reacting the corresponding ketone with C(6)F(5)MgBr, followed by acidic work-up. The alcohols were characterized by NMR, vibrational spectroscopy, single-crystal X-ray diffraction, acidity measurements and gas-phase electron diffraction. A combination of appropriate 2D NMR experiments allowed the unambiguous assignment of all signals in the (19)F spin systems, of which that of 2 was especially complex. High acidity of the alcohols is indicated by acidity measurements as well as the calculated gas phase acidities. It is also supported by the crystal structure of 2, which exhibits only a single weak intermolecular hydrogen bridge with an O...O distance of 301 pm. This shows the low donor strength of the oxygen atom in the compound, which is partly compensated through formation of two intramolecular CF...H contacts of 220 and 232 pm length to the proton not involved in the hydrogen bridge. The pK(a) values in acetonitrile are 22.2 for 1 and 22.0 for 2; their calculated gas phase acidities are 1367 and 1343 kJ mol(-1) (MP2/TZVPP level).     

Bromodifluoroacetyl fluoride,CF2BrC(O)F: Experimental and theoretical studies

Bromodifluoroacetyl fluoride, CF₂BrC(O)F, was prepared through the gas-phase reaction of bromotrifluoroethene, CF₂CFBr, with molecular oxygen initiated either by NO₂ or CF₃OF. The compound was experimentally studied by FTIR spectroscopy of the gas phase and also isolated in Ar and N₂ matrices at low temperature. The energy differences between the possible conformers were theoretically studied, as well as the vibrational spectra of the conformers.