Iridium oxide fluoride

For M(V) and M(VI), no binary compounds with the heavier halogens and no oxides are known. Iridium(VI) fluoride is the precursor to [Ir(CO)g] +, the only example to date of a tripositive, binary metal carbonyl cation. Compare reaction... 

The pattern of iridium halides resembles rhodium, with the higher oxidation states only represented by fluorides. The instability of iridium(IV) halides, compared with stable complexes IrCl4L2 and the ions IrX (X = Cl, Br, I), though unexpected, finds parallels with other metals, such as plutonium. Preparations of the halides include [19]... 

In research al the Institute or Radiochemistry. Karlsruhe, West Germany during Ihe early 1970s. investigators prepared alloys of Curium with iridium, palladium, plalinum. and rhodium. These alloys were prepared by hydrogen reduction of the curium oxide or fluoride in the presence of finely divided noble metals. The reaction is called a coupled reaction because the reduction of the metal oxide can be done in the presence of noble metals. The hydrogen must be extremely pure, w ith an oxygen content of less than 10 -s Inrr. 

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. 

Iridium hexafluoride also proved able to oxidize CI2 The molar combining ratio is closer to 1 1 and, as in the case of PtFg, no evidence has been found for free chlorine fluorides in the product. Unfortunately the product is amorphous to X-rays the yellow solid is unstable at room temperature and decomposes ts. 231 to iridium pentafluoride [Z ] and a gaseous decomposition product, other than chlorine, that has not been identified. Should the Raman and infrared studies presently being carried out prove the presence of ClJlIrFe] in the adduct then it would follow that (irFi) > —144 kcahmole . ... 

Iridium hexafluoride like PtF, is a sufficiently powerful oxidizer to liberate fluorine in the mildly exothermic 1 1 reaction at 20°, the sole solid product being the salt NO+[IrF,] . These reactions are of special interest as being chemical preparations for fluorine which can be carried out at room temperature, using reactants which can be preserved indefinitely at normal temperatures and pressures. Since the enthalpy of dissociation of ONF(g) -y ON(g) -F F(g) has been given as -F55 kcal. mole t, AH for the process ONF(g) -y + I (g) + is 268 kcal. mole-. A minimum electron affinity of MF, for an exothermic reaction ONF -F IrF, -> ON+[IrF,] -F F would therefore be —143 kcal. mole, although for the liberation of molecular fluorine this would be reduced to —125 kcal. mole . The efficient formation of ONF, when an excess of nitrosyl fluoride is employed, suggests the interaction of the excess of ONF with a reaction intermediate such as ONIrF,. Presumably this intermediate does not dissociate to form atomic fluorine it is... 

Although a number of complex fluorides of quinquevalent iridium, (e.g. KIrF,) are known, previous attempts to establish the simple fluoride have failed. The absence of a pentafluoride of iridium has become increasingly anomalous as the pentafluorides of the neighbouring elements, rhenium, osmium, and platinum have been prepared. Previous work - indicated that reactions which might have yielded the pentafluoride gave the tetrafluoride instead. The physical properties of this tetrafluoride. (m.p. 106—107 b.p. > 300 ), however, resembled those of a pentafluoride or oxide tetrafluoride. This indicated that iridium tetrafluoride differed structurally from its neighbouring tetrafluorides. 

In 1958, the fluoride long known[l] as OsFg was shown by Weinstock and Malm [2] to be OsFg and, in 1965, the fluoride of iridium, reported [3,4] on two occasions to be a tetraflu.oride was shown [5] by Bartlett and Rao to be a pentafiuoride. New hexafluorides [4,6-8] and pentafiuorides[9-ll] (in addition to RuFj which had long been known) have now established hexafluorides and pentafluorides for all of the platinum metals other than palladium. Moreover, the trifluorides, RuFj, RhFr, PdFi and IrFr have been established by X-ray crystal structure analysis [12] although that of palladium has been shown [13] to be the mixed oxidation state compound Pd(II) Pd(IV)F6. So far only one di-fluoride of the platinum metals, PdF2, has been reported[14-16]. 

The room temperature oxidation of gold, ruthenium, osmium, iridium, platinum, or palladium with fluorine in anhydrous hydrogen fluoride... 

G. Lucier, S. H. Elder, L. Chacon and N. Bartlett, The Room Temperature Oxidation of Gold, Ruthenium, Osmium, Iridium, Platinum, or Palladium with Fluorine in Anhydrous Hydrogen Fluoride, European J. Solid State Inorg. Chem. 33 (1996) 809-820. 

Iridium(V) complexes, 1158 fluorides, 1158 Iridium(VI) complexes, 1158 Iron complexes acetonitrile, 1210 analysis, 1180, biological systems, 1180 coordination geometries, 1183 coordination numbers, 1182-1187 dinitrosyldicarbonyl, 1188 Mdssbauer spectroscopy, 1181 nitric oxide, 1187-1195 nitrosyls binary, 1188 bis(dithiolene), 1193 carbonyl, 1188 dithiocarbamates, 1192 halides, 1193 iodide, 1193... 

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