Tungsten triiodide

Tungsten triiodide [15513-69-6] prepared by the action of iodine on tungsten hexacarbonyl in a sealed tube at 120°C (18). 

Undoubtedly, the best method for the production of pure anhydrous lanthanide trihalides involves direct reaction of the elements. However, suitable reaction vessels, of molybdenum, tungsten, or tantalum, have to be employed silica containers result in oxohalides (27). Trichlorides have been produced by reacting metal with chlorine (28), methyl chloride (28), or hydrogen chloride (28-31). Of the tribromides, only that of scandium has been prepared by direct reaction with bromine (32). The triiodides have been prepared by reacting the metal with iodine (27, 29, 31, 33-41) or with ammonium iodide (42). 

Containment of this particular combination of metal, trichloride, and HO at reaction temperatures presents a problem of the same character as occurs in the preparation of the triiodides of these elements (this volume. Chapter 1, Sec. 6). These metals all dissolve in (reduce) the liquid trichlorides to some d ee, and this process greatly accelerates the spontaneous reduction of SiO by the metal to form silicide and oxide. The same problem pertains to all known ceramic materials. Container metals which are the most inert to both the rare earth elements and HQ are limited to tungsten and molybdenum and then only if reactions such as Mo(s) + 4HCl(g) -> MoCl4(g) + 2H2(g) are suppressed by the addition of H2. The last is not a serious problem for example, with Phj/Pho > 10 the pressures of all gaseous molybdenum chlorides are estimated to be <10 atm at 800°. Molybdenum is the material of choice because of its greater ease of fabrication." ... 

ClftHi2AS2Co2FftOe, /i (1,2-Bis(dimethylarsino)tetrafluorocyclobutene-As,As)-di-/ix carbonyl-bis-(dicarbonylcobalt) (Co-Co), 37B, 641 Cl ftHi 2AS2FijFe206, 1, 2-Bis(dimethylarsino)-3,3,4,4-tetrafluorocyclo-butenebis(iron tricarbonyl), 31B, 466 32B, 374 Cl4H16AS2IftOftW, Tetracarbonyliodo(o-phenylenebis(dimethylarsino))-tungsten(II) triiodide, 40B, 1034... 

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