Iridium pentafluoride

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 . ... 

The 1 1 chlorine trifluoride-platinum pentafluoride adduct, m. p. I7l , and the 1 1 iodine pentafluoride adduct, m. p. 140° resemble, in their physical properties, the selenium tetrafluoride adducts of osmium pentafluoride (SeF4,OsFg, m. p. 158°) and iridium pentafluoride (SeF. IrFg, m. p. 133°). They are probably bifluorine-bridged monomers ... 

Table 2 gives some of the physical properties of the known pentafluorides. Iridium pentafluoride is isomorphous and nearly isodimensional with ruthenium pentafluoride and presumably has the nonlinear fluorine-bridged tetrameric molecular structure, reported by Holloway, Peacock, and Small for that fluoride. In this arrangement the... 

Binary Compounds. The fluorides of indium are IrF [23370-59-4] IrF [37501-24-9] the tetrameric pentafluoride (IiF ) [14568-19-5], and JIrFg [7789-75-7]. Chlorides of indium include IrCl, which exists in anhydrous [10025-83-9] a- and p-forms, and as a soluble hydrate [14996-61-3], and IrCl [10025-97-5], Other haUdes include IrBr [10049-24-8], which is insoluble, and the soluble tetrahydrate IrBr -4H20 IrBr [7789-64-2]-, and Irl [7790-41-2], Iridium forms indium dioxide [12030-49-8], a poorly characteri2ed sesquioxide, 11203 [1312-46-5]-, and the hydroxides, Ir(OH)3 [54968-01-3] and Ir(OH) [25141-14-4], Other binary iridium compounds include the sulfides, IrS [12136-40-2], F2S3 [12136-42-4], IrS2 [12030-51 -2], and IrS3 [12030-52-3], as well as various selenides and teUurides. 

Dining the reduction of iridium hexafluoride, osmium hexafluoride or rhenium hexafluoride with silicon to the pentafluorides, the hexafluorides must not be condensed directly onto undiluted silicon powder, or explosions may result [1]. The same is true for molybdenum hexafluoride and uranium hexafluoride [2],... 

In its chemical properties, the oxyfluoride behaves as a derivative of five-positive platinum. Potassium hexafluoroplatinatc(v) (Found F, 32-0. KPtF, requires F, 32-7%) is formed when the oxyfluoride vapour is passed over hot potassium fluoride and when potassium fluoride is mixed with the oxy-fluoridc in iodine pentafluoride solution. Potassium hexafluoroplatinatc(v) has a rhombohedral unit cell with a = 4-97 A, a = 97-5°, and is isomorphous with its ruthenium, osmium, and iridium analogues. Dissolution of the oxyfluoride in chlorine trifluoride and in iodine p>entafluoride yields 1 1 platinum penta-fluoridc-solvent adducts. 

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. 

We have now established the pentafluoride of iridium and believe that the previously reported tetrafluoride was the pentafluoride. 

Rhodium pentafluoride is isomorphous with its ruthenium, osmium, and iridium analogues, the crystal data being a, 12-28 b, 9-86 c, 6-48 A ]3, 99-2° Uobs-, 654-2 A Z = 8. Presumably the structural unit of this compound is a fluorine-bridged tetramer, as in ruthenium pentafluoride. It is noteworthy that the unit-cell volume is smaller than in the ruthenium analogue, possibly as a... 

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 establishment of pentafluorides of rhodium and iridium [5] as well as the trifluorides raised the possibility of each element also making a tetrafluoride[17]. On the other hand the mixed oxidation state character [13] of PdFj (Pd(II)Pd(IV)F6) raised the possibility of the tetrafluorides RhF4 and IrF4 being M(III)M(V)F8 compounds. At the same time the existence of Pd(IV) in the compound Pd(II)Pd(IV)F6 indicated the probable existence of PdF4. 

Rhodium(VI) and iridium(VI) occur only in black RhFg and yellow IrFg, formed by heating the metals with F2 under pressure and quenching the volatile products. Both RhFg and IrFg are octahedral monomers. The pentafluorides are made by direct combination of the elements (equation 22.100) or by reduction of MFg, and are moisture-sensitive (reaction 22.101) and very reactive. They are tetramers, structurally analogous to NbFs (22.5). 

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