Rhenium III Iodide

Methylbromoarsines, synthesis 26 Vanadium(III) fluoride, synthesis 27 Sulfur(IV) fluoride, synthesis 33 Peroxydisulfuryl difluoride, synthesis 34 Trichloro(tripyridine)chromium(III), synthesis 36 Tris(3-bromoacetylacetonato)chromium(III), synthesis 37 Trichloro(tripyridine)molybdenum(III), synthesis 39 Uranyl chloride 1-hydrate, synthesis 41 Rhenium(III) iodide, synthesis 50 Potassium hexachlororhenate(IV) and potassium hexa-bromorhenate(IV), synthesis 51 Iron-labeled cyclopentadienyl iron complexes, synthesis 54 Inner complexes of cobalt(III) with diethylenetriamine, synthesis 56... 

The hard black rhenium (IV) iodide is transferred to a test tube 30 cm. long and 25 mm. o.d., which has been constricted to about 10-mm. i.d. at the center. Five grams of iodine is placed on the tetraiodide and the tube is evacuated (oil-pump) and sealed. The tube is heated at 350 5° for 8 hours in a furnace. The tube is then adjusted in such a manner that the rhenium(III) iodide which has formed is maintained in one portion in the furnace at 220° while the other portion protrudes from the furnace. The latter portion is allowed to cool slowly at first and is then cooled further by a jet of air. When all the iodine has apparently collected in the cooled portion, the entire tube is allowed to cool to room temperature. The tube is then scored in the center with a file and broken. (Care is taken to effect a break without introducing shards of glass into the product.) The glistening black crystals are transferred onto the fritted-glass plate of a tared crucible and washed with carbon tetrachloride until the washings are colorless. (About 400 ml. of solvent is required.) The product is then rinsed with two 20-ml. portions each of ethanol and ethyl ether and dried at 110°. The yield is 16.3 g. or 83%. Anal. Calcd. for Reis Re, 32.8 1, 67.2. Found Re, 33.0 1,67.0. 

Rhenium (III) iodide forms lustrous black needlelike crystals. It is only sparingly soluble in water and dilute... 

ReCl6K2 Potassium hexachloro-rhenate(IV), 1 178 7 189 Rela Rhenium (III) iodide, 7 185-187... 

Binary Systems and Related Compounds.—Halides. The vapourization characteristics of ReBr3 have been studied by effusion techniques and the enthalpy and entropy of sublimation determined as 200 kJ mol and 227 e.u. (per mole of trimer), respectively.The X-ray characteristics of rhenium(iii) iodide, prepared from HRe04 and HI in MeOH at 80-90 °C, have been reported. 

The external rhenium unit is removed from 92 through iodine oxidation, and its place is taken by an iodide ligand in 93 (7 74). The reactivity of iodine towards clusters therefore can lie in one-electron oxidation (Section II), electrophilic attack (Section III,B), or partial degradation. 

This is, as expected, the rarest oxidation state as far as non-organometallic complexes of rhenium are concerned. The dirhenium phosphite complex Re2[P(OMe)3]10 has been prepared12,13 in low yield by several methods, viz. the potassium-potassium iodide reduction of ReOCl3(py)2 or an ReCLj-pyridine complex, followed by treatment with trimethyl phosphite. This yellow complex displays a 31P H) NMR spectrum that appears as a first order AB4 pattern, and is isoelectronic with Re2(CO)l0. It reacts with H2 upon photolysis in THF solution to produce hydridorhenium(III) and other species.13 The related triphenyl phosphite derivative Re2[P(OPh)3]l0 has been described14 as a product of the reaction between ReH3(PPh3)4 and P(OPh)3. 

The iodide reaction was first studied by incremental addition of thiosulphate ( The method of constant rates ) . This use of the method was attacked by Bell . Bray s work established the two rate terms shown in Table 28. The reaction has also been studied in the presence of arsenite , which does not interfere as thiosulphate does, and kj =3.3x10 l .mole .sec at 25 °C. Catalysis of the reaction has been demonstrated in presence of vanadium(IV) , ruthenium(III) , rhenium(II) osmium tetroxide " and iron(III) , together with retardation by Mn(II) - Ni(II) and chloride . These measurements were made at moderate acidities and appear to involve quite different dependence of rate on acid concentration from the reaction in absence of catalyst (half-order for Ru(OH), first-order for Re ). The mechanisms may also be quite different. 

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