1.3.2.4- Dithiadiphosphetane 2,4-disulphides reactions

N.m.r. spectroscopic evidence has been provided to suggest the dissociation of relatively simple 1,3,2,4-dithiadiphosphetane 2,4-disulphides (i.e. those with non-bulky groups) in solution this evidence comprises the observed inversion at one of the phosphorus atoms (i.e. cis/trans interconversion) and the exchange reactions... 

The interaction of trialkyl or triaryl esters of phosphorotetrathioic acid with P S q at 180° leads to a scrambling of P-SP and P-SC bonds. The products consist of mixtures of 1,3,2,4-dithiadiphosphetane 2,4-disulphides (76) and the perthiodiphosphates (77), the former being formed in large excess. The same products are obtained in essentially the same ratios from P S q and the thiols RSH. In the case of alkane-a,u-dithiols, the products are the dithiaphosphorinanes (78) and (79), both of which are isolable. This last reaction, during which the cyclic acids (80) appear not to be involved, proceeds well for n=2 or 3, but poorly when n=4. ... 

Before going on to consider some of the very valuable reactions of anhydrosulphides, both in the general context of organophosphorus chemistry and also from the viewpoint of more conventional organic synthesis, it is worth considering them briefly from the structural point of view. The so-called thionophosphine disulphides are (generally) dimeric and possess the 1,3,2,4-dithiadiphosphetane 2,4-disulphide structure. As normally prepared, the compounds exist in the trans form 207, as evidenced by X-ray analyses of, for example the 2,4-dimethyl , 2,4-diphenvl (powder structure) 2,4-bis(4-methoxyphenyl) and 2,4-bis(2,4,6-triisopropylphenyl) compounds. Evidence has been obtained which clearly demonstrates the ability of the cyclic structure to dissociate and re-form under varied con-... 

On the other hand, reactions of the thionophosphine disulphides (1,3,2,4-dithiadiphosphetane 2,4-disulphides) have been reported in abundance. Many of these reactions have been known for some years and have been reviewed more fully else-... 

In particular, the chemical reactions and uses of 2,4-bis(4-methoxyphenyl)-l,3,2,4-dithiadiphosphetane 2,4-disulphide (55) have been widely investigated during the last two decades. The reagent is conveniently prepared on a large scale by heating together at ca 150 a mixture of red phosphorus, sulphur and methoxybenzene in the molar propor-... 

Dithiadiphosphetans.—2,4-Disubstituted 1,3,2,4-dithiadiphosphetan 2,4-disulphides (155) are the anhydrides of dithiophosphonic acids. They have been prepared by the reaction of (156) with The di-t-butyl derivative (155 ... 

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