IV Bromide

Kida and H. Yoneda Nippon Kagaku Zasshi (J. Chem. Soc. Japan, Pure Chem. Sect.), 76, 1059 (1955). 

Submitted by P. J. H. CARNELL, R. E. McC.ARLEY,f and R. D. HOCUEl Checked by FRED W. MOORE4 MELVIN L. LARSON, and ALAN K. MALLOCK  

Preparation of the anhydrous molybdenuin(IV) halides is a difficult task because of the relative ease of disproportionation 

Molyhdenumilll) Bromide. This compound is conveniently prepared from the elements in an apparatus such as that illustrated in Fig. 6. Bulbs A, B, E, and F are sections of 25-mm.-o.d. Vycor tubing joined together by sections of 15-mm.-o.d. tubing. Bulb B should be 2 to 3 in. long, and bulbs E each about 6 in. long. In a typical preparation, 3 g. of molybdenum foil (cut into small strips) is placed in B, and the apparatus 

The preparation of molybdenum (III) bromide is effected by transferring the reaction tube to a 12-in. split-winding furnace D with a heating zone of 10 to 12 in., so that B is located at the center of the furnace. After the furnace has been heated to 600°, bromine is distilled from A to F simply by moving the ice bath to F and warming A to room temperature. A deposit of molybdenum (III) bromide is obtained at B as the reaction proceeds. When all bromine has been distilled into F, the ice bath is returned to A and the distillation repeated. Once the furnace temperature has been regulated, the reaction does not require further attention except to occasionally transfer the ice bath between A and F. 

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Tin IV) bromide, SnBr4. M.p. 33°C, b.p. 203 C, prepared from the elements. Fonns many complexes, including [SnBr ] ions. 

Nitryl chloride Ammonia, sulfur trioxide, tin(IV) bromide and iodide... 

Asymmetric induction has been observed in reactions of e-methoxy- and t-hydroxyallyl-stannanes and aldehydes promoted by tin(IV) bromide 25. 

Ans. (a) Iron(II) bromide and iron(III) bromide, FcBr, and FeBr, (b) palladium ID bromide and palladium(IV) bromide, PdBr, and PdBr4 and (c) mercuryd) bromide and mereury(II) bromide. Hg.Br, and HgBr,. (The charges on the cations can be obtained from Table 6-4.)... 

Under the conditions described above, the formation and extraction of molybdenum (IV) bromide proceed at the rate of ca. 0.086 g. hour-1 or 2.1 g. day-1. For example, 6.85 g. of the tribromide afforded 7.53 g. of tetrabromide after an extraction... 

Molybdenum (IV) bromide is a black crystalline solid which is very sensitive to oxidation and hydrolysis it should be handled only under a dry inert atmosphere. Its solubility in bromine at 51° is ca. 3.0 g./lOOO g. of bromine, and bromine solutions were found to be nonconductors. For example, at 25° both the solvent bromine and a 0.96 X 10 3 M solution in molybdenum (IV) bromide exhibited a specific conductance of 1.3 X 10-10 ohm-1 cm.-1 At 110 to 130° in vacuo, solid molybdenum (IV) bromide decomposes quantitatively into molyb-denum(III) bromide and bromine, and because of this thermal instability it cannot be sublimed except under a bromine atmosphere. 

A. Diisopropoxytitanium(lV) dibromide (Note 1). A 50-mL, two-necked, round-bottomed pre-weighed flask equipped with a magnetic stirring bar, a rubber septum, and an argon inlet is charged with 20 mL of hexane (Note 2) and titanium(IV) bromide (7.3 g, 20 mmol) (Note 3). To the red-brown suspension is added titanium(IV)... 

Titanlum(IV) bromide is purchased from Aldrich Chemical Company, Inc. This material is very moisture sensitive and is therefore weighed and transferred under an argon blanket. 

IV) bromide (IV) chloride (di-) dibromide dibromide oxide (di-) dichloride dichloride oxide difluoride oxide (IV) fluoride (VI) fluoride (di-) hexasulfide (IV) oxide... 

Nitropropane Nitrosyl fluoride Nitrosyl perchlorate Nitrourea Nitrous acid Nitryl chloride Oxalic acid See under Nitromethane chlorosulfonic acid, oleum Haloalkenes, metals, nonmetals Acetones, amines, diethyl ether, metal salts, organic materials Mercury(II) and silver salts Phosphine, phosphorus trichloride, silver nitrate, semicarbazone Ammonia, sulfur trioxide, tin(IV) bromide and iodide Furfuryl alcohol, silver, mercury, sodium chlorate, sodium chlorite, sodium hypochlorite... 

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