Rhenium compounds with osmium

Aspects of the apparatus for the synthesis using metal atoms are described. The reactions of the atoms of rhenium, tungsten, and osmium with hydrocarbons including alkanes are described. It is shown that metal atom reactions with alkanes can give isolable organometallic compounds including l-alkylidene compounds. 

Only two transition metal heptafluorides are known. Rhenium hep-tafluoride is stable, but osmium heptafluoride is so unstable that no structural results for the solid compound have been reported (4). The rhenium compound is cubic (92) at room temperature, with unit-cell dimension a = 6.26(2) A, which is the same as that for rhenium hexafluoride (Table V). This cubic form is stable to -90°C, when a transition occurs to a form of lower symmetry, for which unit-cell dimensions are unknown (92). 

Phillips and Timms [599] described a less general method. They converted germanium and silicon in alloys into hydrides and further into chlorides by contact with gold trichloride. They performed GC on a column packed with 13% of silicone 702 on Celite with the use of a gas-density balance for detection. Juvet and Fischer [600] developed a special reactor coupled directly to the chromatographic column, in which they fluorinated metals in alloys, carbides, oxides, sulphides and salts. In these samples, they determined quantitatively uranium, sulphur, selenium, technetium, tungsten, molybdenum, rhenium, silicon, boron, osmium, vanadium, iridium and platinum as fluorides. They performed the analysis on a PTFE column packed with 15% of Kel-F oil No. 10 on Chromosorb T. Prior to analysis the column was conditioned with fluorine and chlorine trifluoride in order to remove moisture and reactive organic compounds. The thermal conductivity detector was equipped with nickel-coated filaments resistant to corrosion with metal fluorides. Fig. 5.34 illustrates the analysis of tungsten, rhenium and osmium fluorides by this method. 

The electrochemical properties of a number of isostructural rhe-nium(V) oxo, rhenium(V) imido, osmium(VI) nitrido, of formula [M(E)(X)(Y)(Tp )] (Tp = Tp or Tp, E = O, N-tolyl, N X, Y = hydrocarbyl, halide, triflate), have been described. The reactivity of these complexes as inner-sphere oxidants does not correlate with their peak reduction potentials, whereas the ease of the oxidation of these compounds well parallels their reactivity as oxidants.206... 

No infomiation has been found in the literature for phase equihbria and isothermal sections of ternary R-5compounds with ideal compositions have been investigated. The systems with hafnium, tantalum, tungsten, rhenium, and osmium as 5d-element have not been studied. The Pm-5[Pg.33]

The direct aminolysis of metal oxides with primary amines is a useful synthetic route for imido compounds of rhenium and osmium (equation 41). 

These early successes with carbonyl complexes of rhenium encouraged me to undertake systematic research on the carbon monoxide chemistry of the heavy transition metals at our Munich Institute during the period 1939-45, oriented towards purely scientific objectives. The ideas of W. Manchot, whereby in general only dicarbonyl halides of divalent platinum metals should exist, were soon proved inadequate. In addition to the compounds [Ru(CO)2X2] (70), we were able to prepare, especially from osmium, numerous di- and monohalide complexes with two to four molecules of CO per metal atom (29). From rhodium and iridium (28) we obtained the very stable rhodium(I) complexes [Rh(CO)2X]2, as well as the series Ir(CO)2X2, Ir(CO)3X, [Ir(CO)3]j (see Section VII,A). With this work the characterization of carbonyl halides of most of the transition metals, including those of the copper group, was completed. 

The NO + MF, (except NO -f WF,) reactions proceed spontaneously at 20°. The reactions were followed tensimetrically. Gaseous products were identified by infrared spectroscopy and the solid products were examined by. y-ray powder-photography. Both ReF, and OsF, formed NO+[MF,] (cub.) salts and neither salt could be induced to combine with more NO to yield the quadrivalent (NO),MF, compound. In their reactions with nitrosyl fluoride at 20°, however, the rhenium and osmium fluorides are clearly differentiated ReF, readily forms a thermally stable 2 1 adduct, which is isomorphous with (NOjjWFg, whereas the OsF, -i- ONF reaction is complex. The identification of small quantities of nitrogen oxide trifluoride, in the gaseous product of the reaction, indicate the existence of an... 

Tetrahydroborate complexes with third-row transition metals are much less abundant than for first or second row metals. Only complexes with lanthanum, hafnium, tungsten, rhenium and osmium have been characterised by diffraction techniques. For each metal, only a few compounds are known, making conclusions less reliable regarding the M - B distances. 

An important contribntion to solid hot atom chemistry came from H. Muller s laboratory in Freiburg with rhenium (osmium) compounds (Muller 1979). Muller performed his studies on mixed crystal systems involving rhenium, osmium, etc., for many years. An advantage of rhenium (n,y) recoil reaction is its relatively small recoil energy ( max 102 eV, average energy may be much lower for Re), which results in a reaction zone with a radius of ca. 0.5 nm (one or two unit cells of the crystal lattice). 

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