Complex fluorides of iridium and osmium

Abstract

Complex fluorides of the general formula M(I)M(v)F,, where M(I) = Li, Na, K, Rb, Cs, Ag, and M(v) = Ir, Os, involving quinquevalent iridium and osmium have been prepared and characterised. Further, the preparation of complexes of the formula M(I)&(Iv)F,, where M(I) = K, Cs, and M(Iv) = Ir, Os, is also described. Evidence is presented to show that complexes of the types M(I)IrF, and M(I)OSF,, where M(I) = Na, I<, do not exist.HITHERTO the known complex halides of iridium and osmium were the chloride and bromide, and, for osmium only, the iodide. Those of iridium, derived from the sexacovalent element in the ter-and quadri-valent conditions, had the forrnulz M(I)~I~(III)C~, and M(1)$r(1v)C16 respectively ; those of osmium included the isomorphous chloro-osmates M(I),OS(IV)C~, and also a sexavalent series containing the osmyl, Oso,, grouping.Attempts to obtain complex fluorides from the chloroiridates and aqueous hydrogen fluoride were not successful (cf. Sharpe, J., 1950, 3444). Schlesinger and Tapley (J. Amer. Chem. Soc., 1924, 46, 276), however, claim to have prepared K21rF6 and PbIrF, from powdered iridium and potassium plumbifluoride, K3HPbF,. The classic work of Ruff and his collaborators ( [1913][1914][1915][1916][1917][1918][1919][1920][1921][1922][1923][1924][1925][1926][1927][1928][1929][1930], although mainly directed to the making of simple fluorides, e.g., IrF6, IrF,, OsF,, OsF,, and OsF,, included the observations that fluorination of metallic iridium or osmium intimately mixed with an alkali-metal fluoride, yielded white, salt-like substances. No analyses or further information about these compounds was given and the present communication describes a reopening of the subject in which, by using bromine trifluoride as the fluorinating agent, we have been able to prepare new complex fluorides. These compounds are of special interest in that they are the first in which the metals osmium and iridium have been shown to exhibit a valency of five. EXPERIMENTAL Comfilex Fluorides of QuinquevalentIridium-The bromine trifluoride was prepared as previously described (J., 1954, 1197). As the reagent does not react a t room temperature with metallic iridium and only slowly and very incompletely a t its boiling point, a bromide was substituted for the element and proved ideal for the preparations. The iridium bromide was prepared by dissolving good-quality sodium chloroiridate (Found : Ir, 34.1. Calc. for Na2IrC1,,6H,o: Ir, 34.4%) in 10% hydrochloric acid and heating the solution to 70-80" with a slight excess of " AnalaR" ammonium chloride. After 12 hr. the black crystals of ammonium chloroiridate were collected on a fritted-glass filter, well washed under suction with dilute hydrochloric acid, with 50% aqueous alcohol, both cooled to 0", and, finally, with (v), KIrF,, a white solid sparingly soluble in bromine trifluoride and readily freed from bromine (b) Mixture KBr : 1rBr3r5 = 2 : 1 and 3 : 1.KIrF,,KF,0.5BrF3 requires Ir, 40.9% ; equiv., 472).Complex Fluorides of Quadrivalent Iridium.-( 1) Potassium hexafluoroi...

The electronic spectra of the hexafluoro complexes of the second and third transition series

“…)(47, 48), and for K2OsF6 a magnetic moment of 1.48 B.M. at 300 °K has been reported(49), which is in accordance with the expectation of a low- 4.…”

“…The hexafluoroosmate(V) salts are readily obtained by the action of BrF3 on 1 : 1 mixtures of OsBr4 and the appropriate alkali metal chloride (47,48). A magnetic moment of 3.23 B.M.…”

Synthesis and Characterization of Barium Hexafluoridoosmates

“…BaOsF 6 was obtained by dissolving Ba(OsF 6 ) 2 in water and evaporating the solution at 80 • C. Upon the addition of water the solution became pale yellow and small gas bubbles appeared, which was reported to be OsO 4 [1]. When the water was completely evaporated, a mixture of a black powder with colorless crystals was obtained.…”

“…We used bromine trifluoride as the oxidizing and fluorinating medium for the synthesis of Ba(OsF 6 ) 2 [1]. A stoichiometric mixture of BaF 2 and osmium metal was loaded into a vessel made of FEP (perfluorinated ethylene-propylene copolymer) and covered with an excess of BrF 3 .…”

“…The first compounds containing these species were prepared by Hepworth and coworkers [1]: MOsF 6 (M = Li, K, Rb, Cs, Ag) and M 2 OsF 6 (M = K, Cs), and were later characterized by various techniques, such as IR spectroscopy [2][3][4][5][6] and X-ray diffraction [7][8][9]. Both anions can be of relevance for the urban mining processes [10,11] and the analytical chemistry of osmium [12,13].…”