High- und Low-Spin-Verhalten des Ni3+ -Ions in oktaedrischer Koordination. (A) NiF-Polyeder

High and Low Spin Behaviour of Ni³⁺?Ions in Octahedral Coordination The compounds Cs₂NaNiF₆, Cs₂KNiF₆, Rb₂KNiF₆, K₃NiF₆, and Na₃NiF₆ were investigated by ligand field and EPR spectroscopy between 298 and 4,2 K. These fluorides ? with the exception of the first one – crystallise in the cubic elpasolite lattice or in distorted modifications of this structure type and contain the Ni³⁺ ions in the low spin configuration te. This configuration is stabilised versus the high spin alternative te by an appreciable Jahn-Teller splitting of the ²E_g-state of about 7000 cm^?1. The NiF₆-octahedra are tetragonally elongated, the distortion being dynamical at 298 K. In case of the cubic compound Rb₂KNiF₆ a transition to a tetragonal structure with c/a > 1 as a consequence of a ferrodistortive Jahn-Teller ordering is observed at lower temperatures. It is calculated from the anisotropic g-parameters, that the first excited quartet level ⁴A_2g(⁴T_1g ? te) has an energy which is about 1000 cm^?1 higher than that of the ²A_1g(²E_g ? te) groundstate. Spin-orbit interactions between the energetically neighboured ²A_1g(²E_g) and ⁴A_2g, ⁴E_g(⁴T_1g) states lead to third order contributions to the g-factors, which are very sensitive with respect to the doublet-quartet separation. In the hexagonal compound Cs₂NaNiF₆ finally, in which half of the Ni³⁺ ions occupy octahedral sites connected by common corners as in the other fluorides, while the other half is located in octahedral sites with common faces, high and low spin Ni³⁺ ions are found side by side. Obviously the latter half of these Ni³⁺ ions is geometrically restricted with respect to a Jahn-Teller distortion and hence the high spin configuration energetically favoured.     

Darstellung,Kristallstruktur und Schwingungsspektren von (n-Bu4N)2[(Mo6I)(NCS)]

Synthesis, Crystal Structure, and Vibrational Spectra of (n-Bu₄N)₂[(Mo₆I)(NCS)] By treatment of [(Mo₆I)I]^2– with (SCN)₂ in dichloromethane at –20 °C the hexaisothiocyanato cluster anion [(Mo₆I)(NCS)]^2– is formed. The X-ray structure determination of (n-Bu₄N)₂[(Mo₆I)(NCS)] · 2 Me₂CO (monoclinic, space group P2₁/c, a = 13.168(5), b = 11.964(5), c = 24.636(5) Å, β = 104.960(5)°, Z = 2) shows, that the thiocyanate groups are coordinated exclusively via N atoms with Mo–N bond lengths of 2.141–2.150 Å, Mo–N–C angles of 166–178° and N–C–S-angles of 174–180°. The vibrational spectra exhibit characteristic innerligand vibrations at 2073–2054 (ν_CN), 846–844 (ν_CS) and 480–462 cm^–1 (δ_NCS).     

19F-NMR-spektroskopischer Nachweis und statistische Untersuchung zur Bildung der gemischten Clusteranionen [(Mo6ICl)F]2−, n = 0–7, und Darstellung von (TBA)2[(Mo6I)F]

¹⁹F NMR Spectroscopic Evidence and Calculation of the Statistical Formation of Mixed Cluster Anions [(Mo₆I Cl )F ]^2?, n = 0–7, and Preparation of (TBA)₂[(Mo₆I )F ] The octa-μ₃-iodo-hexafluoro-hexamolybdate(2?)ion [(Mo₆I)F]^2? is prepared for the first time. The system of the 21 innersphere mixed clusters (Mo₆ICl)⁴⁺, n = 0–7 is formed by exchange of innersphere bound Clⁱ against outersphere bound I^a on tempering solid [(Mo₆Cl)I] at 400°C. Prolonged tempering leads to increasing average n values of the mixture, which is converted into the tetrabutylammonium salt (TBA)₂[(Mo₆ICl)F]. Using increments of chemical shifts and integral peak intensities the 54 ¹⁹F-nmr signals of the 21 species (compound n = 8 is absent) are assigned and confirmed by the 2 D-¹⁹F/¹⁹F-COSY spectrum. From the measured intensities the distribution of the different compounds is determined and proves significant deviation from statistical occupation, revealing the preference of isomers with iodine atoms occupying edges of the innersphere cube and discrimination of those sharing diagonals of the faces. Moreover all compounds with n = 3 and 4 are present overaverage in comparison to the others.     

Dicyanmethanido- und Cyanamido-oxoanionen. Untersuchungen zum sauerstoffanalogen Charakter der C(CN)2- und NCN-Gruppen

The equivalence of the C(CN)₂- and the NCN-groups with oxygen in the series of homologous ions C(CN), N(CN), OCN^? and NOC(CN), NO causes us to postulate a more general value of this relation. Arguments for the formulation of a pseudochalkogen series C(CN)₂? NCN? O are discussed. Synthesis, structure and reactivity of some dicyanmethanido- and cyanamido-oxoanions RCOY^?, CO₂Y^2?, COY, NOY^?, NO₂Y^?, PO₃Y^3?, PO₂Y and SO₂Y^2? are described. (Y ? C(CN)₂, NCN.) The preparation of some triorganoleadacyles is reported.     

Der Jahn-Teller-Effekt des Mn3+-Ions in oktaedrischer Fluorkoordination. Ligandenfeldspektroskopische und magnetische Untersuchungen

Jahn-Teller Effect of Mn³⁺ Ions in Octahedral F^?-Coordination. Ligand Field Spectroscopic and Magnetic Investigations From the ligand field spectra of Mn^IIIF polyhedra in different host lattice structures [AB^IMnF₆ (elpasolite type); B^IIMnF₅; A^IMnF₄ (CsFeF₄ type)] remarkable splittings of the octahedral ⁵E_g groundstate as the consequence of a tetragonal (or lower symmetry) Jahn-Teller component are deduced. The splittings vary between 8500 and 15500 cm^?1 and can be correlated with the extent of Jahn-Teller distortion in the Mn^IIIF polyhedra. While the cooperative Jahn-Teller order is of ferrodistortive symmetry in the elpasolite-structure [exception: (NH₄)₃MnF₆], the tetragonally elongated Mn^IIIF octahedra exhibit an antiferrodistortive order in compounds A^IMnF₄, as was possible to conclude from the magnetic structures found at lower temperatures. The intensities of the sharp, spin-forbidden quintet-triplet transitions in the ligand field spectra vary strongly in dependence on the temperature and the cooperative magnetic order observed for the different classes of compounds.     

Comparison of theory and experiment for excited singlet states of the H2 molecule

This paper presents a survey of published and unpublished ab initio calculations of the vibrational structures of the ten lowest electronic singlet states of the hydrogen molecule up to the H(n = 1) + H(n = 2) dissociation limit. The data are based on adiabatic potential functions (clamped-nuclei electronic energies and nuclear-mass-dependent diagonal corrections). Nonadiabatic coupling has been treated ab initio within the five states. of ¹Λ symmetry (X,EF, GK, HH?) and ¹Σ I.¹Π_g. The accuracies of the theoretical energies are determined by comparisons with experimental data for H₂, HD, and D₂. The level shifts and predissociation probabilities of the excited ¹Σ states, generated by nonadiabatic coupling with the discrete and continuous vibrational structure of the ground state, and radiative properties have also been calculated.     

Über das Auftreten von Monoselenan- und Monotelluran-disulfandiphosphonat bei der Umsetzung von SPO mit Seleno- und Telluropolythionaten

On the Formation of Monoselenane and Monotellurane Disulphane-diphosphonate by the Reaction of SPO with Seleno and Telluropolythionates In the reaction of seleno- and telluropolythionates with SPO, SeS₂P₂O and TeS₂P₂O are formed and are described for the first time. Polysulfphane-diphosphonates, -disulphonates and -phosphonsulphonates occur as side and consecutive products. By evaluation of radiochemical double labelling with the nuclide pairs ³⁵S? ³²P and ³⁵S? ⁷⁵Se, it is possible to identify the products formed and obtain information about the reaction mechanism.     

Synthese und Strukturuntersuchungen von Iodocupraten(I). IX. Synthese und Kristallstrukturen von Cs3Cu2I5 und RbCu2I3

Syntheses and Structure Analyses of Iodocuprates (I). IX. Syntheses and Crystal Structures of Cs₃Cu₂I₅ and RbCu₂I₃ Cs₃Cu₂I₅ and Rb[Cu₂I₃] were prepared by the reaction of CsI or RbI with CuI in solution (acetonitrile or acetone) or by solid state reaction. The crystal structure analysis of Cs₃Cu₂I₅ (orthorhombic, Pbnm, a = 1438.6(6), b = 1014.7(5), c = 1167.5(5) pm, Z = 4) shows, that the compound contains dinuclear anions Cu₂I₅^3? in which the I atoms are arranged to trigonal bipyramids; one Cu^I occupies one of the two I tetrahedral holes, the other a trigonal site of the neighbouring tetrahedron. Rb[Cu₂I₃] (orthorhombic, Cmcm, a = 1070.6(7), b = 1338.3(8), c = 572.8(3) pm, Z = 4) is built up by CuI₄ double chains; the compound is isomorphic with Cs[Cu₂I₃].     

Photoelectrochemistry with Colloidal Semiconductors; Laser Studies of Halide Oxidation in Colloidal Dispersions of TiO2 and α-Fe2O3

Aqueous sols of TiO₂ (anatase, particle radius 25 Å) were excited with (347.1 nm)-laser light and the reaction of valence-band holes with halide ions (X = I^?, Br^?, Cl^?) was investigated. Hole transfer takes place within the duration of the (10 ns)-laser pulse and results in the formation of anion radicals according to the sequence: The quantum yield of X increases in the order Cl < Br < I, attaining 0.8 for I at pH 1. It is affected by pH, halide concentration and the presence of a protective agent for the sol. RuO₂ deposited onto TiO₂ enhances markedly Cl and Br -formation, but has no effect on the yield of I. Laser-photolysis investigation of halide oxidation were also carried out with colloidal Fe₂O₃ (particle radius 600 Å). For I_2?formation, the quantum yield exceeds 0.9 indicating almost quantitative hole scavenging by iodide.     

Herstellung von Fluorophosphaten,Difluorophosphaten, Fluorophsophonaten und Fluorophosphiten in fluoridhaltigen Harnstoffschmelzen

Preparation of Fluorophosphates, Difluorophosphates, Fluorophosphonates, and Fluorophosphites in Fluoride-containing Urea Melts Phosphoric acid, phosphonic acid, and organylphosphonic acid react on heating in fluoride-containing urea melts in high yields to fluorophosphates, MPHO₂F, organylfluorophosphonates, M¹RPO₂F, organylpolyfluorophosphonates, MR¹CX(PO₂F)₂, MN(CH₂PO₂F)₃, and phosphonoorganylfluorophosphonates, MR¹CX(PO₃)PO₂F (M¹ = K, NH₄; R = organic substituent; R¹ = H, organic substituent; X = OH, NH₂, NR₂). The reaction mechanism of the formation of fluorophosphate ions in fluoride containing urea melts is discussed.     

Die Kristallstruktur von Ag3Co(CN)6

The crystal structure of the hexagonal Ag₃Co(CN)₆ (a = 7.03 Å, c = 7.13 Å, Z = 1) has been determined by X-ray powder methods. The structure factor calculations based on the space group D lead to a reliability index R of 0.062, the R̃-value from F²-sums of systematically coinciding reflections being 0.064. The cobalt atoms are located in the position 1 a (0,0,0), the silver atoms in 3g (1/2,0,1/2;0,1/2,1/2;1/2,1/2,1/2). The carbon and nitrogen atoms occupy the position 6k. The interatomic distance are: Co-C = 1.89 Å, C-N = 1.14 Å, Ag-N = 2.06 Å. The angle C-N-Ag is 157.3º.     

Übergangsmetallchalkogenverbindungen. Monothiodiselenomolybdate(VI) und -wolframate(VI) Darstellung,Elektronenspektrum und röntgenographische Untersuchung

The preparation of MMoOSSe₂ and MWOSSe₂ (M^I = Cs, Tl) is reported. The measured IR and electronic absorption spectra are discussed. It was found by X-ray studies that both cesium salts are crystallising in the space group D—Pnma with Z = 4 (For dimensions of the unit cell and density see Inhaltsübersicht).     

Dynamische Jahn-Teller Verzerrungen und chemische Bindungsverhältnisse in orbitalentarteten Sandwichkomplexen

In order to derive information on the Jahn-Teller effect and on chemical bonding in orbitally degenerate sandwich molecules, the low-spin d⁵(²E_2g) metallocenes Mn(cp)₂ and Fe(cp) as well as the d⁷(²E_1g) metallocenes Co(cp)₂ and Ni(cp) have been diluted in a variety of diamagnetic host systems and studied by ESR. at liquid helium temperature and slightly higher temperatures. Analysis of the measured anisotropic Zeeman and hyperfine data leads to the conclusions that the Jahn-Teller distortions remain entirely dynamic in all four cases (E_JT ? hv), and that the covalent delocalization of the singly occupied degenerate metal 3d orbital over the ligand rings correlates well with the observed Jahn-Teller distortion increasing strongly along the series Fe(cp) < Mn(cp)<₂ < Co(cp)₂ < Ni(cp). This finding agrees with the expectation that the ligand components of the singly occupied e_2g(e_1g*) orbitals are mainly responsible for the dynamic e_1g(e_2g) distortions in the cyclopentadienyl rings.     

Darstellung und Kristallstruktur von trans-(Ph4As)2[OsCl2(NCS)(SCN)], Schwingungsspektren und Normalkoordinatenanalyse

Preparation and Crystal Structure of trans-(Ph₄As)₂[OsCl₂(NCS) (SCN) ], Vibrational Spectra and Normal Coordinate Analysis By treatment of trans-[OsCl₂I₄]^2? with (SCN)₂ in dichloromethane a mixture of different linkage isomers is formed, from which trans-[OsCl₂(NCS)(SCN)]^2? has been isolated by ion exchange chromatography on diethylaminoethyl cellulose. The X-Ray structure determination on a single crystal of trans-(Ph₄As)₂[OsCl₂(NCS)(SCN)] (triclinic, space group P 1 , a = 12.505(5), b = 12.056(5), c = 19.833(5) Å, α = 108.047(5)°, β = 91.964(5)°, γ = 117.048(5)°, Z = 2) reveals that two cis-positioned Thiocyanate(N) groups are coordinated with Os? N? C angles of 172.1° and 173.0° and two cis-positioned Thiocyanate(S) groups are coordinated with Os? S? C angles of 106.9° and 108.7°. Using the molecular parameters of the X-Ray determination the low temperature (10 K) IR and Raman spectra of the (n-Bu₄N) salt of the linkage isomer are assigned by a normal coordinate analysis based on a modified valence force field. The valence force constants are f_d(OsN) = 1.63 and f_d(OsS) = 1.30 mdyn/Å. Taking into account the trans influence a good agreement between observed and calculated frequencies is achieved.     

Structures and Electrical Properties of Some New Organic Conductors Derived from the Donor Molecule TMET (S,S,S,S,-Bis(dimethylethylenedithio) tetrathiafulvalene)

Crystal structures and electrical properties of radical-cation salts of the chiral organic donor TMET (S,S,S,S,-bis-(dimethylethylenedithio)tetrathiafulvalene) are described. Two structural types, 2:1 with octahedral anions Pf, AsF, SbF, I (incommensurate), and 3:2 with tetrahedral anions BF^?₄, CIO^?₄, ReO^?₄ are observed. Resistivity measurements between 2 and 298 K indicate that the 3:2 types are organic metals, while the other compounds are semiconductors. (TMET)₃(CIO₄)₂ is metallic down to about 120 K at ambient pressure and remains metallic down to 2 K at 8 kbar.     

A Flory–Huggins thermodynamic approach for predicting sorption equilibrium in ternary polymer systems

The Flory–Huggins theory as modified by Pouchlý has been applied to calculate preferential (λ) and total (Y) sorption coefficients for a ternary polymer system. The ternary interaction function (?₁?₂?₃G_T(u₁, ?₃)) is described as the product of three independent binary functions. This expression allows prediction of λ and Y from binary interaction parameters χ, χ, g, g, and g₁₂(?₁₀). Three ternary polymer systems are used to check the validity of the expression. Moreover for polymer systems in which the parameters g and/or g are unknown, a procedure to evaluate them has been developed and verified on systems for which sufficient experimental information is available.     

The lowest order relativistic corrections for the hydrogen molecule

We have calculated the lowest order relativistic corrections for the X ¹Σ, B¹Σ, a³Σ, b³Σ, I¹Π_g, C¹Π_u, i³Π_g, c³Π_u, J¹Δ_g, and j³Δ_g states of the hydrogen molecule using variational Monte Carlo methods and compact, explicitly correlated trial wavefunctions. Our values are in good agreement with earlier calculations on the X¹Σ and B¹Σ states. For the other states, our work provides the first estimate of these properties. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

19F-NMR-spektroskopischer Nachweis und Berechnung der statistischen Bildung der gemischten Clusteranionen [(Mo6BrCl)F]2−, n = 0 – 8

¹⁹F NMR Spectroscopic Evidence and Calculation of the Statistical Formation of Mixed Cluster Anions [(Mo₆Br Cl )F ]^2?, n = 0 – 8 The complete system of the innersphere mixed clusters (Mo₆BrCl)⁴⁺ is formed by exchange of innersphere bound Clⁱ against outersphere bound Br^a on tempering the solid [(Mo₆Cl)Br] at 500°C for 16 h. After conversion with conc. HCl into (H₃O)₂[(Mo₆BrCl)Cl] and precipitation of the outer Cl^a with AgBF₄ in ethanol, treatment with tetrabutylammonium(TBA)fluoride yields (TBA)₂ [(Mo₆BrCl)F], a mixture of 22 different species. According to the sets of chemical equivalent fluorine atoms in total 55 ¹⁹F nmr signals are expected, which are really observed in the high resolution 1D-¹⁹F-nmr spectrum. Using increments of chemical shifts, peak intensities and multiplet structures as well as the 2D-¹⁹F/¹⁹F-COSY spectrum the complete and unambiguous assignment of all resonances is achieved. From the measured integral intensities the distribution of the different compounds is determined, revealing statistical formation of the geometrical isomers.     

Struktur und Eigenschaften von Gd3I3C

Structure and Properties of Gd₃I₃C . The compound Gd₃I₃C is prepared by reaction of Gd, GdI₃ and C (2:1:1 mole) at 1 250 K in sealed Ta tubes. It is obtained as bronze-coloured needles which are air and moisture sensitive. The structure of Gd₃I₃C contains twin chains of C centered Gd₆ octahedra surrounded by I atoms capping all free edges like in the M₆X₁₂ cluster. The one-dimensional units are oriented along [010] and linked according to (GdGd_1/3Gd_2/2Gd_2/3C)₂IIII. Gd₃I₃C is metallic in the temperature range 300 K ≥ T ≥ 120 K, between 120 and 15 K the electrical resistance increases by 6 orders of magnitude. At high temperatures the susceptibility follows the Curie-Weiß law with a paramagnetic Curie temperature θ ≈ - 340 K. Two local maxima in the susceptibility at 100 K and 25 K indicate successive formation of antiferromagnetically ordered structures.     

Zur Kenntnis komplexer Fluoride mit Cu2+ und Pd2+: MPtF6 (M  Pd,Cu) und RbCuPdF5

On Complex Fluorides with Cu²⁺ and Pd²⁺: MPtF₆ (M ? Pd, Cu) and RbCuPdF₅ For the first time single crystals of PdPtF₆ (green), trigonal-rhomboedric, a = 503.8, c = 1431.6 pm, spcgr. R3 ? C (No. 148), Z = 3, CuPtF₆ (orange), triclinic, a = 495.2, b = 498.5, c = 962.4 pm, α = 89.98, β = 104.23, γ = 120.35°, spcgr. P1 ? C (No. 2), Z = 2 and RbCuPdF₅ (orange brown, in connection with investigations on M^IPd₂F₅ [1]), orthorhombic, a = 626.9, b = 719.9, c = 1076.3 pm, spcgr. Pnma? D (No. 62), Z = 4, four circle diffractometer data, have been obtained.