Übergangsmetall-methylen-komplexe: LVI. Organoruthenium-komplexe mit offenkettigen und carbocyclischen alkyliden-brücken: Synthese,konstitution, isomerie,protonierung und thermolytischer abbau

The eighteen new μ-alkylidene ruthenium complexes 5a–r and 5t are very easily and cleanly obtained along the diazoalkane or the hydrazone routes that involve treatment of the dinuclear, metal-metal doubly bonded precursor compound [(η⁵-C₅H₅)Ru(μ-NO)]₂ (3) either with the diazoalkanes oxidizing agent (e.g., MnO₂), with the respective hydrazones. Similarly, sulfur dioxide adds cleanly to the RuRu double bond of 3, thus giving the complex (μ-SO₂)[(η⁵-C₅H₅)Ru(NO)]₂ (5s). Regardless of the nature of the carbene bridge ligands, the dimetallacyclopropanes exhibit, in contrast to their iron analogues, exclusively terminal nitrosyl ligands. cis/trans-Isomerism with predominating amounts of the trans-isomers is observed for the derivatives that display unsymmetrically substituted carbene bridges.Treatment of the μ-methylene- and μ-ethylidene complexes (μ-CH₂)[(η⁵-C₅H₅)Ru(NO)]₂ (5a) and (μ-CHCH₃)[(η⁵-C tetrafluoroboric acid or trifluoromethanesulfonic acid in diethyl ether yields, at ambient temperature, quantitatively the ionic complexes 6a,b and 7a,b, respectively, which were shown by ¹H NMR spectroscopy to contain metal-metal bridging hydrogen functionalities. The reaction of hydrogen bromide with 5a under the same conditions gives the neutral bromo(methyl) complex 6d. This latter compound results from the isolable ionic intermediate of composition [(μ-CH₂)(μ-H){(η⁵C₅H₅)Ru(NO)}₂]⁺Br^? (6c), which reaction stems from the nucleophilicity of the halide ion present in 6c.     

Protolytic surface reactions of a fluorapatite-maghemite mixture in aqueous suspension

Synthetically prepared maghemite and fluorapatite, characterized with BET, SEM, XRD, FT-IR, and FT-Raman, are used to investigate the protolytic properties and surface characteristics in a mixed system of maghemite and fluorapatite by means of potentiometric titrations and surface complex modeling. Titrations were performed in the pH range of 7.3-10.5 at 25 +/- 0.2 degrees C in ionic media of 0.10 mol dm(-3) NaNO3 with 0.0100 mol dm(-3) HNO3 and 0.0100 mol dm(-3) NaOH used as titrants. The constant capacitance model (CCM) was applied to interpret the titration data. Two models with different surface equilibria were tested. In the first model, the mixed system was treated as a one-component system with a total surface area of 40.04 +/- 5.2 m2 g(-1) without any consideration to the subsystems. The surface equilibria, triple bond XOH + H+ <==> triple bond XOH2+, beta(s)(-11)(int) = 6.74 +/- 0.07; XOH <==> triple bond XO- + H+, beta(s)(-11)(int) = -7.75 +/- 0.07, were found to represent an accurate model for the system, and the specific capacitance was optimized to 2.0 F m(-2). The number of active surface sites N(s) was found to be 1.2 sites nm(-2). This model has, however, no relation to the subsystems of maghemite and fluorapatite. The second model is related to the subsystems and displays the surface equilibria, triple bond S2OH<==> triple bond S2O- + H+, beta(s)(-101)(int) = -9.12 +/- 0.01; triple bond FeOH + H+<==> triple bond FeOH2+, lg beta(s)(-11)(int) = 6.80 +/- 0.01; triple bond FeOH<==>FeO- + H+, beta(s)(-11)(int) = -7.77 +/- 0.01, where S2OH is related to fluorapatite and FeOH is representing maghemite. Fluorapatite corresponds to the dominating active surface in the system. The specific capacitance was optimized to 18 F m(-2). The N(s) values were found to be 2.27 sites nm(-2) for fluorapatite and 0.80 sites nm(-2) for maghemite. The N(s) values together with evidence from the FT-Raman and SEM investigations reveal that interactions between maghemite and fluorapatite surfaces occur during the titration. The acid-base properties and surface characteristics of the subsystems maghemite-H+ and fluorapatite-OH- using the CCM have been published earlier.     

Multiple Bonds between Transition Metals and “Bare” Main Group Elements: Links between Inorganic Solid State Chemistry and Organometallic Chemistry

The last two decades have seen a dramatic development in the study of metal-metal multiple bonds, particular successes being recorded in the field of organometallic chemistry. Syntheses designed to produce novel transition metal complexes with single, double, triple and quadruple metal-metal bonds occupy a most important place in such research, as also do reactivity studies. A striving to establish general principles has provided much of the motivation for such work, but one less obvious goal—the commercial application of the catalytic properties of metal-metal multiple bonding systems, in the medium and long term—should not be overlooked. All aspects of the investigations of metal-metal multiple bonds also apply to a particular class of compound that has, however, enjoyed little lime-light and thus deserves the present review: complexes with multiple bonds between transition metals and substituent-free (“bare”) main group elements. Although based mostly on accidental discoveries, the few noteworthy examples are now beginning to unfold general concepts of synthesis that are capable of being extended and thus are deserving of exploitation in preparative chemistry. The availability of further structural patterns exhibiting multiple bonds between transition metals and ligand-free main group elements might enable preparative organometallic chemistry to expand in a completely new direction (for instance by the stabilizing or activation of small molecules at the metal complex). This essay discusses the chemistry of complexes of bare carbon, nitrogen, and oxygen ligands (carbido-, nitrido-, and oxo-complexes) and their relationships to higher homologues from both a synthetic and a structural point of view.     

Relaxometric study of copper [15]metallacrown-5 gadolinium complexes derived from alpha-aminohydroxamic acids

Proton nuclear magnetic relaxation dispersion (NMRD) profiles were recorded between 0.24 mT and 1.4 T for lanthanum(III)- and gadolinium(III)-containing [15]metallacrown-5 complexes derived from alpha-aminohydroxamic acids and with copper(II) as the ring metal. The influence of the different R-groups on the proton relaxivity was investigated, and a linear relationship between the relaxivity and the molecular mass of the metallacrown complex was found. The selectivity of the metallacrown complexes was tested by transmetalation experiments with zinc(II) ions. The crystal structure of the copper [15]metallacrown-5 gadolinium complex with glycine hydroximate ligands is reported.     

Chain-length dependence of the conformational order in self-assembled dialkylammonium monolayers on mica studied with soft X-ray absorption

Self-assembled alkyl chain based monolayers on mica are important for industrial and technological processes since they can be employed for an organic modification of the inorganic substrate. The conformational structure and orientational order of the films determine the interaction of the modified substrate with the environment and the chemical character and stability of its surface. We have studied the conformational order in ion exchanged dialkylammonium monolayers adsorbed on mica depending on the length of the alkyl chains systematically with near-edge X-ray absorption fine structure spectroscopy (NEXAFS). In addition, films were characterized by water contact angle measurements. The experimentally determined average tilt angles of the chains are discussed in terms of the degree of order. It was found that the absolute number of gauche defects in the films increases with decreasing chain length.     

Neutral and ionic aluminum,gallium, and indium compounds carrying two or three terminal ethynyl groups

The syntheses of the ionic compounds [Li(+).2 dioxane (2,6-iPr(2)C(6)H(3)N(SiMe(3))Al(C triplebond CSiMe(3))(3))(-)].0.75 dioxane (1), [(Li(+))(2).(dioxane)(7)](0.5) [2,6-iPr(2)C(6)H(3)N(SiMe(3))Ga(C triplebond CSiMe(3))(3)(-)].1.5 dioxane (2), and [(Li(+))(2).(dioxane)(7)](0.5) [2,6-iPr(2)C(6)H(3)N(SiMe(3))In(C triplebond CSiMe(3))(3)(-)].1.5 dioxane (3) by the reaction of the corresponding organo metal chloride with LiC triplebond CSiMe(3) are reported. The neutral ethynyl compounds Br-Al(C triplebond CtBu)(2).2 THF (4), Cl-Ga(C triplebond CtBu)(2).THF (5), Cl-In(C triplebond CtBu)(2).2 THF (6), Al(C triplebond CtBu)(3).C[N(Me)CMe](2) (7), Ga(C triplebond CtBu)(3).dioxane (8), and In(C triplebond CtBu)(3).NEt(3) (9) have been obtained in good yields from the reaction of AlBr(3), GaCl(3), and InCl(3) with LiC triplebond CtBu in the presence of a Lewis base. Compound 7 is the first heterocyclic carbene substituted ethynyl derivative. Aluminum and gallium compounds with three terminal ethynyl groups Al(C triplebond CPh)(3).NMe(3) (10) and Ga(C triplebond CPh)(3).NMe(3) (11) have been prepared by the reaction of AlH(3).NMe(3) or GaH(3).NMe(3) with three equivalents of phenylethyne. All the above-mentioned compounds have been structurally studied. In compound 1 the lithium ion is coordinated to the three terminal ethynyl groups, whereas in compounds 2 and 3 the lithium is coordinated to the solvent (dioxane). Compound 8 crystallizes as a coordination polymer with dioxane molecules bridging the individual gallium units.     

Spectrophonic humidity-trace detection in hydrogen and air

A spectrophone with low resonant frequency compatible with the repetition frequency of a pulsed discharge CO laser is described. The spectrophone is used for humidity detection in hydrogen and air. The simple and inexpensive system provides a detection capacity of 10–100ppb/ . The responsivity of the resonant spectrophone is interpreted taking the dependence of the acoustical quality factor on the geometry into account.     

Verdampfung von Uranspaltprodukten in Wasserstoff, Stickstoff und Sauerstoff

Zusammenfassung Die Verdampfung der Spaltprodukte Germanium, Arsen, Molybdän, Ruthenium, Cadmium, Zinn, Antimon und Tellur aus bestrahltem U₃O₈ im Wasserstoff-, Stickstoff- und Sauerstoffstrom wurde zwischen 900 und 1500° C untersucht. Bei 1500° C verdampfen die meisten dieser Elemente innerhalb 1 Std mit hoher Ausbeute.

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Summary The volatization of the fission products germanium, arsenic, molybdenum, ruthenium, cadmium, tin, antimony and tellurium from neutron-irradiated uranium oxide in flowing hydrogen, nitrogen or oxygen of atmospheric pressure was investigated between 900 and 1500° C. At 1500° C, most of these elements are volatized with high yield within one hour.

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Herrn Prof. Dr. F. Strassmann danken wir herzlich für die Förderung dieser Arbeit, Herrn I. Bonner für seine Mitarbeit, den Betriebsstäben der Forschungsreaktoren Frankfurt und München, insbesondere Herrn Dr. G. Wolf (Frankfurt), für Bestrahlungen und dem Bundesministerium für wissenschaftliche Forschung für finanzielle Beihilfen.

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Herrn Prof. Dr. W. Geilmann zum 75. Geburtstag gewidmet.

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Aus einer Dissertation, Mainz 1963.     

Hydrogen determination by means of the1H(19F, αγ)16 O and1H(15N, αγ)12C resonance reactions

Hydrogen surface contamination and depth profiles can be measured by the resonant nuclear reactions¹H(¹⁹F, )¹⁶O and¹H(¹⁵N, )¹²C. The method was applied to study hydrogen-implanted silicon, amorphous silicon layers and silicon oxide films produced by anodic oxidation.