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Carbonyl fluorides of platinum metals.

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posted on 19.11.2015, 08:46 by Clifford James. Marshall
A product of the high temperature and pressure carbonylation of ruthenium pentafluoride is shown by X-ray crystallographic techniques to have a molecular structure based on a tetrameric unit, (Ru (CO)3F2)4, having bridging fluorine atoms. The crystal structure is disordered and a model for the disorder is proposed. The physical and chemical properties of the compound are discussed in relation to the known, dimeric dihalogenotricarbonyl- ruthenium compounds, Ru2 (CO)6X4. The fluorination of dodecacarbonyltriruthenium using fluorine or xenon difluoride, at room temperature in chlorofluorocarbon solvents, gives an involatile, moisture- sensitive solid. Spectroscopic, magnetic, and analytical evidence suggests a possible formulation Ru (CO) 3F3 for the solid. Polymeric and ionic structures for such a species are discussed. Fluorination of dodecacarbonyltriosmium, using xenon difluoride, in chlorofluorocarbon solvents gives an involatile, moisture-sensitive solid of composition Os(CO)3F2. Mass and infrared spectroscopic and chemical evidence suggests a polymeric formulation for this compound, (Os(CO)3F2)n. A fluorine-bridged polymeric structure is proposed for (Os(CO)3F2)n. Both the product formulated as Ru (CO)3F3 and (Os(CO)3F2)n are soluble in anhydrous hydrogen fluoride. Dodecacarbonyltetrarhodium and hexadecacarbonylhexarhodium react with xenon difluoride to give similar moisture- sensitive solid products of uncertain composition. Chemical and spectroscopic evidence suggests that the product is not a single phase and that one component is possibly a carbonyl-bridged, polynuclear rhodium carbonyl fluoride species. A synthesis of dodecacarbonyltetrairidium in up to 50% yield is reported. Two iridium carbonyl chloride species, (Ir (CO)2 (H2 O)Cl2)2 . 2H2O and (Ir (CO)2Cl2)-, are reduced, by carbon monoxide at atmospheric pressure and room temperature in alcoholic solvents and in the presence of sodium bicarbonate or lithium acetate, to give Ir4(CO)12. Dodecacarbonyltetrairidium reacts readily with chlorine, bromine, and iodine but not with xenon difluoride. The moisture-sensitive chlorination and bromination products react with triphenyl- phosphine to give the known, substituted Ir (III) carbonyl halides, IrX3 (CO) (Ph3P)2 and IrHX2 (CO) (Ph3P)2; (X = Cl,Br). It is suggested from this and analytical evidence that the halogenation products may be formulated as (Ir (CO)2X3)2.


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University of Leicester

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