Diphosphine disulfides diphosphines

Related to these diphosphine dichalcogenides are the triphosphine trisulfides [R2P(S)]3CH (12) which can be prepared from lithiated methylene diphosphine disulfides upon treatment with thiophosphinic chlorides (Equation 9). Deprotonation of 12 with tBuLi gives a resonance-stabilised anion 13 containing a planar central carbanion whose charge is delocalised onto the three neighbouring phosphorus and sulfur atoms.32... 

Other related compounds are the diphosphine disulfides R2P(S)P(S)R2 14, which contain a direct phosphorus-phosphorus bond, and polysulfur fe(dior-ganophosphine sulfides) R2P(S)-S -P(S)R2 in which the two phosphorus centres are connected by a chain of one of more sulfur atoms. R2P(S)P(S)R2 compounds are accessible from heating secondary phosphine sulfides with thiophosphinic chlorides (Equation 10) or by reaction of fephosphines with... 

The metal and ammonium salts of dithiophosphinic acids tend to exhibit far greater stability with respect to this thermal decomposition reaction, and consequently these acids are often prepared directly in their salt form for convenience and ease of handling. Alkali-metal dithiophosphinates are accessible from the reaction of diphosphine disulfides with alkali-metal sulfides (Equation 22) or from the reaction of alkali-metal diorganophosphides with two equivalents of elemental sulfur (Equation 23). Alternatively, they can be prepared directly from the parent dithiophosphinic acid on treatment with an alkali-metal hydroxide or alkali-metal organo reagent. Reaction of secondary phosphines with elemental sulfur in dilute ammonia solution gives the dithiophosphinic acid ammonium salts (Equation 24). 

Although diphosphine disulfides of formula R2P(S)P(S)R2 take up a trans conformation in the solid state (see Section 5.2.3), upon coordination to a metal centre they can rearrange to adopt a cis conformation, hence facilitating bidentate chelation of the metal (e.g., Equation 78).117 In addition, a cis-bridging mode has also been proposed for these ligands in bi-metallic complexes.117... 

Cleavage of diphosphines with LiAIH, can be a route to secondary phosphines, e.g., diphosphine disulfides react ... 

The drying of impure ethers can produce a violent explosion. Further information about this hazard may be found in Inorganic Syntheses, Volume 12, p. 317. A hazard associated with the synthesis of tetramethyl-diphosphine disulfide [ Inorg. Synth., 15, 186 (1974)] is cited in Inorganic Syntheses, Volume 23, p. 199. 

Preparation. - The diphosphines (223) can be oxidised to the related dioxides on treatment with oxygen or hydrogen peroxide. Treatment of the diphosphine (223, R = Ph) with an excess of sulfur in hot toluene affords the corresponding bis(sulfide). X-ray studies of representative dioxides and the above disulfide reveal considerable steric strain in the molecule, resulting in out of plane displacement of phosphorus atoms. " The reaction of (223, R = Ph) with an... 

P2S2C4Hi2, Diphosphine, tetramethyl-, disulfide, hazards in preparation of, 23 199 PjS4ZnC7 H60, Zincate(U), tet-rakis(benzenethiolato)-, bis(tetraphenylphosphonium), 21 25 P OujThW, Thorate(lV),... 

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