Osmium, complex fluorides

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. 

Chloroxytrifluoromethane, 26 137-139 reactions, 26 140-143 addition to alkenes, 26 145-146 oxidative addition, 26 141-145 vibrational spectra, 26 139 Chloryl cation, 18 356-359 internal force constants of, 18 359 molecular structure of, 18 358, 359 properties of, 18 357, 358 synthesis of, 18 357, 358 vibrational spectra of, 18 358, 359 Chloryl compounds, reactions of, 5 61 Chloryl fluoride, 18 347-356 chemical properties of, 18 353-356 fluoride complexes of, 5 59 molecular structure of, 18 349-352 physical properties of, 18 352, 353 preparation, 5 55-57 and reactions, 27 176 properties of, 5 48 reactions, 5 58-61, 18 356 synthesis of, 18 347-349 thermal decomposition of, 18 354, 355 vapor pressures, 5 57, 18 353 vibrational spectra of, 18 349-352 Chloryl ion, 9 277 Cholegobin, 46 529 Cholesterol, astatination, 31 7 Cholorofluorphosphine, 13 378-380 h CHjPRj complexes, osmium, 37 274 Chromatium, HiPIP sequence, 38 249 Chromatium vinosum HiPIP, 38 108, 133 Fe4S4 + core, 33 60 Chromato complexes, osmium, 37 287... 

The chemistry of osmium fluorides and fluoro complexes differs sufficiently from that of the chloro, bromo and iodo species to warrant separate treatment here. The early review of Canterford and Colton is still useful for the general halide chemistry of the element.736... 

Direct fluorination of metallic iridium at 543 K has produced the rather unstable, yellow di complex [IrFJ, which is isomorphous with its osmium(VI) analogue. [IrF6] tends toward dissociation, yielding fluorine and lower iridium fluorides. The octahedral [IrF6] species decomposes in water this is accompanied by ozone liberation. The magnetic moment of [IrF6] is jue r = 3.3 BM at... 

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... 

All four halide ions from octahedral complexes with the metal. Fluorides or fluoro complexes are known for osmium(VII) to osmium(IV) inclusive, with rather tenuous evidence for OsFj OsF is a rare example of seven coordination for the metal. The other halides prefer the IV and III states, though osmium(V) chloride and chloro complexes have recently been made and also [OsBr ]". Although [RuFs] " is well known there is no osmium analogue, in keeping with the general tendency of third-row elements to display higher oxidation states than their second-row partners. 

Osmium(VII) complexes bisimido, 559 fluorides, 612 hexaoxo,588 imido,558 monooxo, 588... 

With the metals of the first transition series, the maximum coordination number of higher oxidation states is six, and this is so firmly fixed that in their fluoride complexes the oxidation state of the metal in question can be fixed by controlling the mol fraction of alkali metal present 26). Thus, the fluorination of a vanadium salt in the presence of a one, two, or three mol ratio of potassium ion, yields KV F6, KgWVFe, or KsV Fe. The same tendency is shown, but to a lesser degree, by metals of the second transition series, as exemplified by KRuFe and KgRuFe. For an unusual example in the third series, note that OsFe is known, OsFt is not stable, but heptavalent osmium is found as six-coordinated OsOFs (27). 

Evidence that the halides have an effect on the electron density at the metal center has been achieved by measuring the enthalpies of protonation of metal complexes containing the four different halogens. - As shown in Equation 4.118, these studies show that the absolute value of the enthalpy of protonation of the osmium-fluoride complex at the metal center is much larger than that of the protonation of the chloride complex, which is larger than that of the protonation of the bromide and iodide complexes. 

Osmium(III), d, compounds consist of the halide salts, except fluoride, and complexes involving halides, amines, and acetylacetonate, as well as some mixed ligand species involving phosphines and arsines. These complexes are... 

Other Reactions. Trityl fluoroborate has been used often to prepare cationic organometallic complexes, as in the conversion of dienyl complexes of iron, ruthenium, and osmium into their cationic derivatives. It alkylates pyridines on the nitrogen atom in a preparation of dihydropyridines and acts as a tritylating agent. It has also been used in attempts to form silyl cations and silyl fluorides from silanes. Finally, it has been reported to be a usefiil desiccant. ... 

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