Heptasulfide

Properties and Reactions. Phosphorus combines with sulfur to form the binary tetraphosphoms trisulfide [1314-85-8] (phosphoms sesquisulfide), P4S2, (1) tetraphosphoms pentasulfide [12137-70-1] ( )j tetraphosphoms heptasulfide [12037-82-0] P) and phosphoms(V)... 

Phosphoms(V) sulfide, an important commodity in the United States since about 1920, is the dominant commercial material. Phosphoms sesquisulfide, P4S2, has been made commercially since about 1900. Phosphoms heptasulfide was introduced as a small-scale commercial product in 1940. 

For more selective hydrogenations, supported 5—10 wt % palladium on activated carbon is preferred for reductions in which ring hydrogenation is not wanted. Mild conditions, a neutral solvent, and a stoichiometric amount of hydrogen are used to avoid ring hydrogenation. There are also appHcations for 35—40 wt % cobalt on kieselguhr, copper chromite (nonpromoted or promoted with barium), 5—10 wt % platinum on activated carbon, platinum (IV) oxide (Adams catalyst), and rhenium heptasulfide. Alcohol yields can sometimes be increased by the use of nonpolar (nonacidic) solvents and small amounts of bases, such as tertiary amines, which act as catalyst inhibitors. 

For Raman spectra of hexa- [30, 40] and heptasulfides [46] with complex univalent cations, see the original literature. 

Technetiummetall. Metallisches Technetiunj wurde durch Reduktion des Heptasulfids Tc S, mit Wasserstoff bei 1100° (29), oder durch Er-hitzen des Ammoniumpertechnetats NH4Tc04 im Wasserstoffstrom bei 500 bis 600° erhalten (17), (82). 

Aus sauren Pertechnetatlosungen kann man das Technetium — ent-sprechend dem Rhenium, aber im Gegensatz zu Mangan — durch fijS als dunkelbraunes bis schwarzes Heptasulfid T S, abscheiden (27), (29),... 

This reagent appears quite frequently in the older literature it was used by Victor Meyer in his classic synthesis of thiophene from disodium succinate. It appears that it is (or was) a mixture, with phosphorus heptasulfide (P4S7) being a major component. Louis and Mary Fieser126 quote, with obvious relish, an out-of-doors preparation from red phosphorus and sulfur which often gives an excellent display of fireworks. A standard preparation of 3-methylthiophene uses the heptasulfide.127... 

Tetraphosphorus pentasulfide, P4S5, is obtained when a solution of sulfur in CS2 reacts with P4S3 in the presence of I2. Tetraphosphorus heptasulfide, P4S7, is one of the products obtained when phosphorus and sulfur are heated in a sealed tube. Neither P4S5 nor P4S7 is commercially important. Tetraphosphorus decasulfur, P4S10, is prepared by reaction of a stoichiometric mixture of the elements. 

Figure 2 Conformations of heptasulfide chains (a) all-trans (++++/ in [PPh4]2 S723 and (b) trans-cis-trans (+- -----) in [H2N(C6Hn)2]2S732...

Although all of the above elements catalyze hydrogenation, only platinum, palladium, rhodium, ruthenium and nickel are currently used. In addition some other elements and compounds were found useful for catalytic hydrogenation copper (to a very limited extent), oxides of copper and zinc combined with chromium oxide, rhenium heptoxide, heptasulfide and heptaselen-ide, and sulfides of cobalt, molybdenum and tungsten. 

The same is true of rhenium catalysts rhenium heptoxide [42], rhenium heptasulfide [5i] and rhenimn heptaselenide [54] all require temperatures of 100-300° and pressures of 100-300 atm. Rhenium heptasulfide is not sensitive to sulfur, and is more active than molybdenum and cobalt sulfides in hydrogenating oxygen-containing functions [55,55]. 

Catalytic hydrogenation of thiophene poses a problem since noble metal catalysts are poisoned, and Raney nickel causes desulfurization. Best catalysts proved to be cobalt polysulfide [425], dicobalt octacarbonyl [426], rhenium heptasulfide [5i] and rhenium heptaselenide [54]. The last two require high temperatures (230-260°, 250°) and high pressures (140, 322 atm) and give 70% and 100% of tetrahydrothiophene (thiophane, thiolene), respectively. 

Rhenium forms two sulfides when heated with sulfur. These are the disulfide, obtained as black leaflets, having formula ReS2 and a density 7.51 g/cm and the heptasulfide, Re2S , a black powdery material of density 4.87 g/cm. ... 

Typically they are prepared by the reaction of cyclo-Sg with a nucleophile in the presence of one of these cations. For example, the reaction of [PPNjSH with cyclo-Sg in ethanol yields the heptasulfide PFN][catena-Sj] 2EtOH. Orange-red crystals of the octasulfide [EGNH]2[catena-S ] are formed on treatment of a solution of cyclo-Sg in formamide with triethylamine and hydrogen sulfide [eqn (12.12)]. ... 

Phosphorus heptasulfide was obtained from the Oldbury Electrochemical Company. It has been shown 2 that the phosphorus trisulfide used by earlier workers for such fusions was actually somewhat impure phosphorus heptasulfide. 

Phosphorous heptasulfide, free from yellow or white phosphorous 1339... 

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